Publications by authors named "Linwei Tian"

138 Publications

Associations of Seasonal Variations and Meteorological Parameters with Incidences of Upper and Lower Gastrointestinal Bleeding.

J Gastroenterol Hepatol 2021 Jul 21. Epub 2021 Jul 21.

School of Public Health, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong, China.

Background: Previous studies have demonstrated the seasonal variations of non-variceal upper gastrointestinal bleeding (UGIB), but there is scanty data on lower gastrointestinal bleeding (LGIB) and the association with other meteorological parameters.

Methods: We included all patients hospitalized for UGIB and LGIB between 2009 and 2018 in Hong Kong. The monthly age- and sex-standardized GIB incidences were fitted to meteorological data including average temperature (AT), maximum temperature (MaxT), minimum temperature (MinT), temperature range (TR), average precipitation, average atmospheric pressure (AtomP) and average relative humidity after adjusting for prescriptions of aspirin, proton pump inhibitors and Helicobacter pylori eradication therapy using the autoregressive integrated moving average (ARIMA) model.

Results: Despite a gradual decline in UGIB incidences, the incidences of UGIB were still higher in winter months. The incidence and fluctuation of both UGIB and LGIB were higher in the older age groups, especially those ≥80 years. The seasonality was only identified in those ≥60 years for UGIB, and only in those ≥80 years for LGIB. UGIB incidence was inversely associated with AT, MaxT and MinT, but positively associated with TR and AtomP. LGIB was also significantly associated with AT, MaxT, MinT and AtomP.

Conclusion: Despite the changes in GIB incidences, the seasonal patterns of GIB were still marked in the elderly. With the ageing population, the impacts of seasonal variations on GIB incidences could be considerable.
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http://dx.doi.org/10.1111/jgh.15632DOI Listing
July 2021

Dietary potato intake and risks of type 2 diabetes and gestational diabetes mellitus.

Clin Nutr 2021 Jun 1;40(6):3754-3764. Epub 2021 May 1.

School of Public Health, Xi'an Jiaotong University Health Science Center, Xi'an, China; Key Laboratory of Environment and Genes Related to Diseases (Xi'an Jiaotong University), Ministry of Education of China, Xi'an, China. Electronic address:

Background & Aims: Evidence regarding associations between potato consumption and type 2 diabetes (T2D) and gestational diabetes mellitus (GDM) risks is accumulating. This study aims to synthesize the evidence by conducting a meta-analysis of available studies.

Methods: PubMed, Web of Science, EMBASE and Cochrane Library were searched (up to August 2020) to retrieve all eligible studies on the associations of interest. The risk estimates with 95% confidence intervals (CIs) were summarized using random- or fixed-effects model based on heterogeneity. Meta-analyses were performed for East and West regions separately. Dose-response relationship was assessed using data from all intake categories in each study.

Results: A total of 19 studies (13 for T2D; 6 for GDM) were identified, including 21,357 T2D cases among 323,475 participants and 1516 GDM cases among 29,288 pregnancies. Meta-analysis detected a significantly positive association with T2D risk for total potato (RR: 1.19 [1.06, 1.34]), baked/boiled/mashed potato (RR: 1.08 [1.00, 1.16]), and French fries/fried potato (RR: 1.33 [1.03, 1.70]) intakes among Western populations. Dose-response meta-analysis demonstrated a significantly increased T2D risk by 10% (95% CI: 1.07, 1.14; P for trend<0.001), 2% (95% CI: 1.00, 1.04; P for trend = 0.02) and 34% (95% CI: 1.24, 1.46; P for trend<0.001) for each 80 g/day (serving) increment in total potato, unfried potato, and fried potato intakes, respectively. As for GDM, summarized estimates also suggested a higher though non-significant GDM risk for total potato (RR: 1.19 [0.89, 1.58]), and French fries/fried potato (RR: 1.03 [0.97, 1.09]) intakes in Western countries. In the dose-response meta-analysis, a significantly increased GDM risk was revealed for each daily serving (80 g) intakes of total potato (RR: 1.22; 95% CI: 1.06, 1.42; P for trend = 0.007) and unfried potato (RR: 1.26; 95% CI: 1.07, 1.48; P for trend = 0.006).

Conclusions: This study suggests that higher potato intake is associated with higher T2D risk among Western populations. The positive relationship presents a significant dose-response manner. Wisely controlled potato consumption may confer potential glucometabolic benefits.
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http://dx.doi.org/10.1016/j.clnu.2021.04.039DOI Listing
June 2021

The joint association of physical activity and fine particulate matter exposure with incident dementia in elderly Hong Kong residents.

Environ Int 2021 May 18;156:106645. Epub 2021 May 18.

School of Public Health, The University of Hong Kong, Hong Kong, China.

Objective: The evidence for the beneficial effects of physical activity (PA) and potentially detrimental effects of long-term exposure to fine particulate matter (PM) on neurodegeneration diseases is accumulating. However, their joint effects remain unclear. We evaluated joint associations of habitual PA and PM exposure with incident dementia in a longitudinal elderly cohort in Hong Kong.

Methods: A total of 57,775 elderly participants (≥65 years) without dementia were enrolled during 1998-2001 and followed up till 2011. Their information on PA and other relevant covariates were collected at baseline (1998-2001) by a standard self-administered questionnaire, including PA volumes (high, moderate, low, and inactive) and types (aerobic exercise, traditional Chinese exercise, stretching exercise, walking slowly, and no exercise). Their annual mean PM exposures at the residential address were estimated using a satellite-based spatiotemporal model. We then adopted the Cox proportional hazards model to examine the joint associations with the incidence of all-cause dementia, Alzheimer's diseases, and vascular dementia on additive and multiplicative scales.

Results: During the follow-up period, we identified 1,157 incident cases of dementia, including 642 cases of Alzheimer's disease and 324 cases of vascular dementia. A higher PA level was associated with a lower risk of incident all-cause dementia (hazard ratio (HR) for the high-PA volume was 0.59 (95% CI, 0.47, 0.75), as compared with the inactive-PA), whereas a high level of PM was related to the higher risk with an HR of 1.15 (95%CI: 1.00, 1.33) compared with the low-level of PM. No clear evidence was observed of interaction between habitual PA (volume and type) and PM inhalation to incident dementia on either additive or multiplicative scale.

Conclusion: Habitual PA and long-term PM exposure were oppositely related to incident dementia in the Hong Kong aged population. The benefits of PA remain in people irrespective of exposure to air pollution.
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http://dx.doi.org/10.1016/j.envint.2021.106645DOI Listing
May 2021

The impact of childhood pneumococcal conjugate vaccine immunisation on all-cause pneumonia admissions in Hong Kong: A 14-year population-based interrupted time series analysis.

Vaccine 2021 05 12;39(19):2628-2635. Epub 2021 Apr 12.

School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China; Centre for Mathematical Modelling of Infectious Diseases, Department of Infectious Disease Epidemiology, London School of Hygiene & Tropical Medicine, London, UK.

Background: Nine years after the introduction of pneumococcal conjugate vaccine (PCV) in the United States, Hong Kong (HK) introduced the vaccine to its universal childhood immunisation programme in 2009. We aimed to assess the impact of childhood PCV immunisation on all-cause pneumonia (ACP) admissions among the overall population of HK.

Methods: In this population-based interrupted time series analysis, we used territory-wide population-representative electronic health records in HK to evaluate the vaccine impact. We identified hospitalised patients with a diagnosis of pneumonia from any cause between 2004 and 2017. We applied segmented Poisson regression to assess the gradual change in the monthly incidence of ACP admissions between pre- and post-vaccination periods. Negative outcome control, subgroup and sensitivity analyses were used to test the robustness of the main analysis.

Findings: Over the 14-year study period, a total of 587,607 ACP episodes were identified among 357,950 patients. The monthly age-standardised incidence of ACP fluctuated between 33.42 and 87.44 per 100,000-persons. There was a marginal decreasing trend in pneumonia admissions after PCV introduction among overall population (incidence rate ratio [IRR]: 0·9965, 95% confidence interval [CI]: 0·9932-0·9998), and older adults (≥65 years, IRR: 0·9928, 95% CI: 0·9904-0·9953) but not in younger age groups.

Interpretation: There was a marginally declining trend of overall ACP admissions in HK up to eight years after childhood PCV introduction. The significance disappeared when fitting sensitivity analyses. The results indicate the complexities of using non-specific endpoints for measuring vaccine effect and the necessity of enhancing serotype surveillance systems for replacement monitoring.

Funding: Health and Medical Research Fund, Food and Health Bureau of the Government of Hong Kong (Reference number: 18171272).
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http://dx.doi.org/10.1016/j.vaccine.2021.03.090DOI Listing
May 2021

Limited role for meteorological factors on the variability in COVID-19 incidence: A retrospective study of 102 Chinese cities.

PLoS Negl Trop Dis 2021 02 24;15(2):e0009056. Epub 2021 Feb 24.

Jockey Club School of Public Health and Primary Care, The Chinese University of Hong Kong, Hong Kong Special Administrative Region, China.

While many studies have focused on identifying the association between meteorological factors and the activity of COVID-19, we argue that the contribution of meteorological factors to a reduction of the risk of COVID-19 was minimal when the effects of control measures were taken into account. In this study, we assessed how much variability in COVID-19 activity is attributable to city-level socio-demographic characteristics, meteorological factors, and the control measures imposed. We obtained the daily incidence of COVID-19, city-level characteristics, and meteorological data from a total of 102 cities situated in 27 provinces/municipalities outside Hubei province in China from 1 January 2020 to 8 March 2020, which largely covers almost the first wave of the epidemic. Generalized linear mixed effect models were employed to examine the variance in the incidence of COVID-19 explained by different combinations of variables. According to the results, including the control measure effects in a model substantially raised the explained variance to 45%, which increased by >40% compared to the null model that did not include any covariates. On top of that, including temperature and relative humidity in the model could only result in < 1% increase in the explained variance even though the meteorological factors showed a statistically significant association with the incidence rate of COVID-19. In conclusion, we showed that very limited variability of the COVID-19 incidence was attributable to meteorological factors. Instead, the control measures could explain a larger proportion of variance.
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http://dx.doi.org/10.1371/journal.pntd.0009056DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7904227PMC
February 2021

Dysregulation of ferroptosis may involve in the development of non-small-cell lung cancer in Xuanwei area.

J Cell Mol Med 2021 Mar 2;25(6):2872-2884. Epub 2021 Feb 2.

Department of Thoracic Surgery I, The Third Affiliated Hospital of Kunming Medical University & Yunnan Cancer Hospital, Kunming, China.

The Xuanwei area of Yunnan Province, China, is one of the regions suffering from the highest occurrence and mortality rate of lung cancer in the world. Local residents tend to use bituminous coal as domestic fuel, which causes serious indoor air pollution and is established as the main carcinogen. After the local government carried out furnace and stove reform work, lung cancer rate including incidence and mortality among residents remains high. We herein wonder if there are specific mechanisms at protein level for the development of non-small-cell lung cancer (NSCLC) in this area. We investigated the changes of protein profiling in tumour of the patients from Xuanwei area. Tandem mass tag (TMT) was employed to screen the differential proteins between carcinoma and para-carcinoma tissues. We identified a total of 422 differentially expressed proteins, among which 162 proteins were significantly up-regulated and 260 were downregulated compared to para-carcinoma tissues. Many of the differentially expressed proteins were related to extracellular matrix (ECM)-receptor interaction, focal adhesion, PI3K/AKT pathway and ferroptosis. Further experiments on the two differential proteins, thioredoxin 2 (TXN2) and haptoglobin (HP), showed that the change of their expressions could make the lung cancer cell lines more resistant to erastin or RSL-induced ferroptosis in vitro, and promote the growth of tumour in nude mice. In conclusion, this study revealed that aberrant regulation of ferroptosis may involve in the development of lung cancer in Xuanwei area.
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http://dx.doi.org/10.1111/jcmm.16318DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7957160PMC
March 2021

Trends of temperature variability: Which variability and what health implications?

Sci Total Environ 2021 May 6;768:144487. Epub 2021 Jan 6.

School of Physics, Peking University, Beijing, China.

A large majority of climate change studies carried out to date are on changes in mean climate, which have comparatively downplayed variability. In terms of trend analysis or forecast, the scientific output and common knowledge for global warming are much more robust than for changes in temperature variability. Quantification of temperature variability adds another dimension of temporal scale, requiring immense labor and presenting great uncertainty. Regardless, this endeavor is necessary since changes in ambient temperature variabilities could also contribute to current and future human health burden besides changes in mean quantities. Here, we review the current literature on trends of surface air temperature variability defined at a range of timescales, aiming to tease out the welter of evidence and thus improving the scientific recognition of changes in air temperature variability in the context of climate change. The findings of reviewed studies from numerous regions differ substantially over various temporal scales. In general, the ambient temperature variability on short time scales (e.g., diurnal or inter-day) shows a downward trend, while it is increasing on longer time scales (e.g., inter-annual). We then move beyond the review and deliver an extended discussion of potential implications for future research related to ambient temperature variability. We highlight the need to consider the methodological choices, especially timescales of interest, in the trend analysis as well as health impact studies. Continued research focusing on temperature variability at multiple timescales, with concerted efforts from scientists of all relevant stripes, is meaningful in synthesizing knowledge and reducing uncertainties surrounding air temperature variability.
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http://dx.doi.org/10.1016/j.scitotenv.2020.144487DOI Listing
May 2021

Long-term exposure to fine particulate matter and dementia incidence: A cohort study in Hong Kong.

Environ Pollut 2021 Feb 25;271:116303. Epub 2020 Dec 25.

School of Public Health, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong, China.

Recent studies suggested that long-term exposure to fine particulate matter (PM) was related to a higher risk of dementia incidence or hospitalizations in western populations, but the evidence is limited in Asian cities. Here we explored the link between long-term PM exposure and dementia incidence in the Hong Kong population and whether it varied by population sub-group. We utilized a Hong Kong Chinese cohort of 66,820 people aged ≥65 years who were voluntarily enrolled during 1998-2001 and were followed up to 2011. Prevalent dementia cases were excluded based on the face-to-face interview at baseline. We ascertained the first occurrence of hospitalization for all-cause dementia and major subtypes during the follow-up period. We assessed PM concentrations using a satellite data-based model with a 1 × 1 km resolution on the residential address. Cox proportional hazards models were adopted to estimate associations of annual mean PM exposure with dementia incidence, adjusting for potential confounders. We identified 1183 incident cases of all-cause dementia during the follow-up period, of which 655 (55.4%) were cases of Alzheimer's disease, and 334 (28.2%) were those of vascular dementia. We found a positive association between annual mean PM exposure and all-cause dementia incidence in the fully adjusted model. The estimated hazard ratio was 1.06 (95% confidence interval (CI): 1.00, 1.13) per every 3.8 μg/m increase in annual mean PM exposure. And the estimated HRs for Alzheimer's disease and vascular dementia were 1.03 (95% CI: 0.94, 1.12) and 1.09 (95% CI: 0.98, 1.22), respectively. We did not find effect modifications by age, sex, BMI, hypertension, diabetes, or heart disease on the associations. Results suggest that long-term exposure to PM is associated with a higher risk of dementia incidence in the Asian population.
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http://dx.doi.org/10.1016/j.envpol.2020.116303DOI Listing
February 2021

Outdoor light at night and risk of coronary heart disease among older adults: a prospective cohort study.

Eur Heart J 2021 02;42(8):822-830

Department of Environmental Health, Boston University School of Public Health, 715 Albany Street, Boston, MA 02118, USA.

Aims: We estimated the association between outdoor light at night at the residence and risk of coronary heart disease (CHD) within a prospective cohort of older adults in Hong Kong.

Methods And Results: Over a median of 11 years of follow-up, we identified 3772 incident CHD hospitalizations and 1695 CHD deaths. Annual levels of outdoor light at night at participants' residential addresses were estimated using time-varying satellite data for a composite of persistent night-time illumination at ∼1 km2 scale. We used Cox proportional hazards models to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) of the association between outdoor light at night at the residence and risk of CHD. The association between light at night and incident CHD hospitalization and mortality exhibited a monotonic exposure-response function. An interquartile range (IQR) (60.0 nW/cm2/sr) increase in outdoor light at night was associated with an HR of 1.11 (95% CI: 1.03, 1.18) for CHD hospitalizations and 1.10 (95% CI: 1.00, 1.22) for CHD deaths after adjusting for both individual and area-level risk factors. The association did not vary across strata of hypothesized risk factors.

Conclusion: Among older adults, outdoor light at night at the residence was associated with a higher risk of CHD hospitalizations and deaths. We caution against causal interpretation of these novel findings. Future studies with more detailed information on exposure, individual adaptive behaviours, and potential mediators are warranted to further examine the relationship between light at night and CHD risk.
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http://dx.doi.org/10.1093/eurheartj/ehaa846DOI Listing
February 2021

Source-Specific Volatile Organic Compounds and Emergency Hospital Admissions for Cardiorespiratory Diseases.

Int J Environ Res Public Health 2020 08 27;17(17). Epub 2020 Aug 27.

School of Public Health, The University of Hong Kong, Hong Kong, China.

Knowledge gaps remain regarding the cardiorespiratory impacts of ambient volatile organic compounds (VOCs) for the general population. This study identified contributing sources to ambient VOCs and estimated the short-term effects of VOC apportioned sources on daily emergency hospital admissions for cardiorespiratory diseases in Hong Kong from 2011 to 2014. We estimated VOC source contributions using fourteen organic chemicals by positive matrix factorization. Then, we examined the associations between the short-term exposure to VOC apportioned sources and emergency hospital admissions for cause-specific cardiorespiratory diseases using generalized additive models with polynomial distributed lag models while controlling for meteorological and co-pollutant confounders. We identified six VOC sources: gasoline emissions, liquefied petroleum gas (LPG) usage, aged VOCs, architectural paints, household products, and biogenic emissions. We found that increased emergency hospital admissions for chronic obstructive pulmonary disease were positively linked to ambient VOCs from gasoline emissions (excess risk (ER%): 2.1%; 95% CI: 0.9% to 3.4%), architectural paints (ER%: 1.5%; 95% CI: 0.2% to 2.9%), and household products (ER%: 1.5%; 95% CI: 0.2% to 2.8%), but negatively associated with biogenic VOCs (ER%: -6.6%; 95% CI: -10.4% to -2.5%). Increased congestive heart failure admissions were positively related to VOCs from architectural paints and household products in cold seasons. This study suggested that source-specific VOCs might trigger the exacerbation of cardiorespiratory diseases.
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http://dx.doi.org/10.3390/ijerph17176210DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7503811PMC
August 2020

Indoor, outdoor, and personal exposure to PM and their bioreactivity among healthy residents of Hong Kong.

Environ Res 2020 09 10;188:109780. Epub 2020 Jun 10.

Institute of Environment, Energy and Sustainability, The Chinese University of Hong Kong, Hong Kong, China; The Jockey Club School of Public Health and Primary Care, The Chinese University of Hong Kong, Hong Kong, China. Electronic address:

Direct evidence about associations between fine particles (PM) components and the corresponding PM bioreactivity at the individual level is limited. We conducted a panel study with repeated personal measurements involving 56 healthy residents in Hong Kong. Fractional exhaled nitric oxide (FeNO) levels were measured from these subjects. Out of 56 subjects, 27 (48.2%) participated in concurrent outdoor, indoor, and personal PM monitoring. Organic carbon (OC), elemental carbon (EC), particle bound-polycyclic aromatic hydrocarbons (PAHs), and phthalates were analyzed. Alteration in cell viability, lactic dehydrogenase (LDH), interleukin-6 (IL-6), and 8-isoprostane by 50 μg/mL PM extracts was determined in A549 cells in vitro. Moderate heterogeneities were shown in PM exposures and the corresponding PM bioreactivity across different sample types. Associations between the analyzed components and PM bioreactivity were assessed using the multiple regression models. Toxicological results revealed that indoor and personal exposure to OC as well as PAH compounds and their derivatives (e.g., Alkyl-PAHs, Oxy-PAHs) induced cell viability reduction and increase in levels of LDH, IL-6, and 8-isoprostane. Overall, OC in personal exposure played a dominant role in PM-induced bioreactivity. Subsequently, we examined the associations of FeNO with IL-6 and 8-isoprostane levels using mixed-effects models. The results showed that per interquartile change in IL-6 and 8-isoprostane were associated with a 6.4% (p < 0.01) and 11.1% (p < 0.01) increase in FeNO levels, respectively. Our study explored the toxicological properties of chemical components in PM exposure, which suggested that residential indoors and personal OC and PAHs should be of great concern for human health. These findings indicated that further studies in inflammation and oxidative stress-related illnesses due to particle exposure would benefit from the assessment of in vitro PM bioreactivity.
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http://dx.doi.org/10.1016/j.envres.2020.109780DOI Listing
September 2020

International Mind, Activities and Urban Places (iMAP) study: methods of a cohort study on environmental and lifestyle influences on brain and cognitive health.

BMJ Open 2020 03 18;10(3):e036607. Epub 2020 Mar 18.

UNSW Ageing Futures Institute and School of Psychology, University of New South Wales, Sydney, New South Wales, Australia.

Introduction: Numerous studies have found associations between characteristics of urban environments and risk factors for dementia and cognitive decline, such as physical inactivity and obesity. However, the contribution of urban environments to brain and cognitive health has been seldom examined directly. This cohort study investigates the extent to which and how a wide range of characteristics of urban environments influence brain and cognitive health via lifestyle behaviours in mid-aged and older adults in three cities across three continents.

Methods And Analysis: Participants aged 50-79 years and living in preselected areas stratified by walkability, air pollution and socioeconomic status are being recruited in Melbourne (Australia), Barcelona (Spain) and Hong Kong (China) (n=1800 total; 600 per site). Two assessments taken 24 months apart will capture changes in brain and cognitive health. Cognitive function is gauged with a battery of eight standardised tests. Brain health is assessed using MRI scans in a subset of participants. Information on participants' visited locations is collected via an interactive web-based mapping application and smartphone geolocation data. Environmental characteristics of visited locations, including the built and natural environments and their by-products (e.g., air pollution), are assessed using geographical information systems, online environmental audits and self-reports. Data on travel and lifestyle behaviours (e.g., physical and social activities) and participants' characteristics (e.g., sociodemographics) are collected using objective and/or self-report measures.

Ethics And Dissemination: The study has been approved by the Human Research Ethics Committee of the Australian Catholic University, the Institutional Review Board of the University of Hong Kong and the Parc de Salut Mar Clinical Research Ethics Committee of the Government of Catalonia. Results will be communicated through standard scientific channels. Methods will be made freely available via a study-dedicated website.

Trial Registration Number: ACTRN12619000817145.
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http://dx.doi.org/10.1136/bmjopen-2019-036607DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7202706PMC
March 2020

Air pollution associated respiratory mortality risk alleviated by residential greenness in the Chinese Elderly Health Service Cohort.

Environ Res 2020 04 15;183:109139. Epub 2020 Jan 15.

Healthy High Density Cities Lab, HKUrbanLab, University of Hong Kong, Hong Kong Special Administrative Region.

Background: Although residing in lower surrounding greenness and transient exposure to air pollution are independently associated with higher risk of adverse health outcomes, little is known about their interactions.

Objectives: We examine whether residential neighborhood greenness modifies the short-term association between air pollution and respiratory mortality among the participants of Chinese Elderly Health Service Cohort in Hong Kong.

Methods: We estimated residential surrounding greenness by measuring satellite-derived normalized difference vegetation index (NDVI) from Landsat within catchments of residential addresses of participants who died of respiratory diseases between 1998 and 2011. We first dichotomized NDVI into low and high greenness and used a time-stratified case-crossover approach to estimate the percent excess risk of respiratory mortality associated with fine particulate matter (PM), respirable particulate matter (PM), nitrogen dioxide (NO), and ozone (O). We further classified NDVI into greenness quartiles and introduced an interaction term between air pollution and the assigned median values of the NDVI quartiles into the models to assess the trend of greenness modification on the air pollution and respiratory mortality associations.

Results: Among 3159 respiratory deaths during the follow-up, 2058 were from pneumonia and 947 from chronic obstructive pulmonary disease. Elders living in the low greenness areas were associated with a higher risk of pneumonia mortality attributed to NO (p = 0.049) and O (p = 0.025). The mortality risk of pneumonia showed a decreasing trend for NO (p for trend = 0.041), O (p for trend = 0.006), and PM (p for trend = 0.034) with greenness quartiles increasing from Quartile 1 (lowest) to Quartile 4 (highest).

Conclusions: Our findings suggest that elders living in higher greenness areas are less susceptible to pneumonia mortality associated with air pollution, which provides evidence for optimizing allocation, siting, and quality of urban green space to minimize detrimental health effects of air pollution.
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http://dx.doi.org/10.1016/j.envres.2020.109139DOI Listing
April 2020

Fine particulate matter and cause-specific mortality in the Hong Kong elder patients with chronic kidney disease.

Chemosphere 2020 May 13;247:125913. Epub 2020 Jan 13.

School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, China. Electronic address:

Emerging epidemiologic studies suggested that particulate matter (PM) was a risk factor for the incidence of chronic kidney disease (CKD). However, few studies were conducted to examine whether PM was associated with cause-specific deaths in the CKD progression. This study aimed to estimate the association between fine particulate matter (PM) and a spectrum of deaths among CKD patients. We took leverage of the Elderly Health Service cohort (n = 66,820), a large Hong Kong elderly cohort followed up till 2010. A total of 902 CKD incident patients in the cohort were identified during the follow-up period. We estimated yearly PM at the residential address for each CKD patient based on a satellite-based spatiotemporal model. We used Cox proportional hazards models with attained age as the underlying timescale to assess the association between long-term exposure to PM and cause-specific mortality among CKD patients. A total of 496 patients died during the follow-up, where 147 died from cardiovascular disease, 61 from respiratory disease and 154 from renal failure. The mortality hazard ratio (HR) per interquartile-range increase in PM (4.0 μg/m) was 1.97 (95% confidence interval (CI): 1.34 to 2.91) for ischemic heart disease (IHD) among CKD patients, and was 1.42 (95%CI: 1.05 to 1.93) for CKD among those patients concomitantly with hypertension. Associations were not of statistical significance between PM and mortality hazard ratios of all-cause, stroke, and pneumonia among CKD patients. Our findings suggest that long-term exposure to PM may contribute to the CKD progression into ischemic heart diseases.
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http://dx.doi.org/10.1016/j.chemosphere.2020.125913DOI Listing
May 2020

Long-Term Exposure to Ambient Fine Particulate Matter and Mortality From Renal Failure: A Retrospective Cohort Study in Hong Kong, China.

Am J Epidemiol 2020 06;189(6):602-612

Numerous studies have indicated that ambient particulate matter is closely associated with increased risk of cardiovascular disease, yet the evidence for its association with renal disease remains underrecognized. We aimed to estimate the association between long-term exposure to fine particulate matter, defined as particulate matter with an aerodynamic diameter less than or equal to 2.5 μm (PM2.5), and mortality from renal failure (RF) among participants in the Elderly Health Service Cohort in Hong Kong, China, from 1998 to 2010. PM2.5 concentration at the residential address of each participant was estimated based on a satellite-based spatiotemporal model. We used Cox proportional hazards regression to estimate risks of overall RF and cause-specific mortality associated with PM2.5. After excluding 5,373 subjects without information on residential address or relevant covariates, we included 61,447 participants in data analyses. We identified 443 RF deaths during the 10 years of follow-up. For an interquartile-range increase in PM2.5 concentration (3.22 μg/m3), hazard ratios for RF mortality were 1.23 (95% confidence interval: 1.06, 1.43) among all cohort participants and 1.42 (95% confidence interval: 1.16, 1.74) among patients with chronic kidney disease. Long-term exposure to atmospheric PM2.5 might be an important risk factor for RF mortality in the elderly, especially among persons with existing renal diseases.
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http://dx.doi.org/10.1093/aje/kwz282DOI Listing
June 2020

Does the AQHI reduce cardiovascular hospitalization in Hong Kong's elderly population?

Environ Int 2020 02 1;135:105344. Epub 2019 Dec 1.

School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong Special Administrative Region. Electronic address:

Background: Air quality alert programs have been introduced around the world to reduce the short term effects of air pollution on health. Hong Kong, a densely populated city in southern China with high levels of air pollution, introduced its first air quality health index (AQHI) on December 30th 2013. However, whether air quality alert program warnings, such as the AQHI, reduces morbidity is uncertain. Using a quasi-experimental design, we conducted the first evaluation of the AQHI in Hong Kong, focusing on cardiovascular morbidity in Hong Kong's elderly population.

Method: Interrupted time series with Poisson segmented regression from 2010 to 2016 was used to detect any sudden or gradual changes in emergency hospital admissions for cardiovascular diseases (CVD), after the AQHI policy was implemented. To account for potential confounders, models were adjusted for air pollutants (NO, SO, PM, O), temperature and humidity. The findings were validated using a negative control and three false policy periods. We also assessed effects on specific subtypes of CVD (hypertensive disease (HPD), acute myocardial infarction (AMI), heart failure, stroke and other CVD) and by sex.

Results: From January 1st 2010 to December 31st, 2016, 375,672 hospital admissions for CVD occurred in Hong Kong's elderly population. Immediately after the policy HPD and AMI dropped by16% (relative risk (RR) 0.84, 95% confidence interval (CI): 0.78-0.91) and 15% (RR 0.85, 95% CI: (0.76-0.97)) respectively. There was no significant change for all CVD or other sub-types and no differences by sex.

Conclusion: Hong Kong's AQHI helped reduced hospital admissions in the elderly for HPD and AMI but had no effect on overall emergency hospitalization for CVD. To maximize health benefits of the policy, at risk groups need to be able to follow the behavioral changes recommended by the AQHI warnings.
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http://dx.doi.org/10.1016/j.envint.2019.105344DOI Listing
February 2020

Benefits of physical activity not affected by air pollution: a prospective cohort study.

Int J Epidemiol 2020 02;49(1):142-152

School of Public Health, The University of Hong Kong, Hong Kong SAR, China.

Background: Physical activity (PA) is beneficial to human health, whereas long-term exposure to air pollution is harmful. However, their combined effects remain unclear. We aimed to estimate the combined (interactive) mortality effects of PA and long-term exposure to fine particulate matter (PM2.5) among older adults in Hong Kong.

Methods: Participants aged ≥65 years from the Elderly Health Service Cohort (n = 66 820) reported their habitual PA at baseline (1998-2001) and were followed up till 31 December 2011. We used a satellite-based spatiotemporal model to estimate PM2.5 concentration at the residential address for each participant. We used Cox proportional hazards regression to assess the interaction between habitual PA and long-term exposure to PM2.5 on cardiovascular and respiratory mortality. We tested for additive interaction by estimating relative excess risk due to interaction and multiplicative interaction employing P-value for the interaction term.

Results: The death risks were inversely associated with a higher volume of PA and were positively associated with long-term exposure to PM2.5. The benefits of PA were more pronounced for participation in traditional Chinese exercise (e.g. Tai Chi) and aerobic exercise (e.g. cycling). We found little evidence of interaction between PA (volume and type) and long-term exposure to PM2.5 on either additive or multiplicative scales.

Conclusions: In this cohort of older Chinese adults, PA may decrease the risk of mortality, be it in areas of relatively good or bad air quality. The beneficial mortality effects of habitual PA outweighed the detrimental effects of long-term exposure to air pollution in Hong Kong.
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http://dx.doi.org/10.1093/ije/dyz184DOI Listing
February 2020

Constituents of Household Air Pollution and Risk of Lung Cancer among Never-Smoking Women in Xuanwei and Fuyuan, China.

Environ Health Perspect 2019 09 5;127(9):97001. Epub 2019 Sep 5.

Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Rockville, Maryland, USA.

Background: Lung cancer rates among never-smoking women in Xuanwei and Fuyuan in China are among the highest in the world and have been attributed to the domestic use of smoky (bituminous) coal for heating and cooking. However, the key components of coal that drive lung cancer risk have not been identified.

Objectives: We aimed to investigate the relationship between lifelong exposure to the constituents of smoky coal (and other fuel types) and lung cancer.

Methods: Using a population-based case-control study of lung cancer among 1,015 never-smoking female cases and 485 controls, we examined the association between exposure to 43 household air pollutants and lung cancer. Pollutant predictions were derived from a comprehensive exposure assessment study, which included methylated polycyclic aromatic hydrocarbons (PAHs), which have never been directly evaluated in an epidemiological study of any cancer. Hierarchical clustering and penalized regression were applied in order to address high colinearity in exposure variables.

Results: The strongest association with lung cancer was for a cluster of 25 PAHs [odds ratio (OR): 2.21; 95% confidence interval (CI): 1.67, 2.87 per 1 standard deviation (SD) change], within which 5-methylchrysene (5-MC), a mutagenic and carcinogenic PAH, had the highest individual observed OR (5.42; 95% CI: 0.94, 27.5). A positive association with nitrogen dioxide ([Formula: see text]) was also observed (OR: 2.06; 95% CI: 1.19, 3.49). By contrast, neither benzo(a)pyrene (BaP) nor fine particulate matter with aerodynamic diameter [Formula: see text] ([Formula: see text]) were associated with lung cancer in the multipollutant models.

Conclusions: To our knowledge, this is the first study to comprehensively evaluate the association between lung cancer and household air pollution (HAP) constituents estimated over the entire life course. Given the global ubiquity of coal use domestically for indoor cooking and heating and commercially for electric power generation, our study suggests that more extensive monitoring of coal combustion products, including methylated PAHs, may be warranted to more accurately assess health risks and develop prevention strategies from this exposure. https://doi.org/10.1289/EHP4913.
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http://dx.doi.org/10.1289/EHP4913DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6792381PMC
September 2019

Respirable Particulate Constituents and Risk of Cause-Specific Mortality in the Hong Kong Population.

Environ Sci Technol 2019 Aug 8;53(16):9810-9817. Epub 2019 Aug 8.

School of Public Health , The University of Hong Kong , Hong Kong SAR , P. R. China.

Emerging studies examined the associations of particulate matter constituents with nonaccidental and cardiorespiratory diseases, but few have investigated more specific causes of cardiorespiratory diseases or other system diseases, especially in Asia. We estimated the association between respirable particulate matter (PM) constituents and a spectrum of deaths using a quasi-Poisson time-series model in Hong Kong. Positive associations were identified between cause-specific deaths and elemental carbon, organic carbon (OC), nitrate, and potassium ion (K), but only the associations for OC and K were robust in the two-constituent models adjusting for other constituents. The estimated effects of OC were strongest on mortality from the respiratory system with cumulative percent excess risk (ER%) of 3.82% (95% CI: 0.96%, 6.92%) per interquartile range (6.7 μg/m) increase over 7 days prior to death (lag), especially for pneumonia (ER%: 4.32%; 95% CI: 0.70%, 8.26%). The digestive system was most sensitive to K with cumulative ER% of 6.74% (95% CI: 0.37%, 14.01%) per interquartile range (0.6 μg/m) increase. This study indicates that PM constituents from biomass burning (OC and K) were more toxic than other constituents for deaths in Hong Kong, especially for mortalities from respiratory and digestive systems. These findings should have potential biological and pollution control implications.
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http://dx.doi.org/10.1021/acs.est.9b01635DOI Listing
August 2019

The effects of particle-induced oxidative damage from exposure to airborne fine particulate matter components in the vicinity of landfill sites on Hong Kong.

Chemosphere 2019 Sep 14;230:578-586. Epub 2019 May 14.

The Jockey Club School of Public Health and Primary Care, The Chinese University of Hong Kong, Hong Kong, China. Electronic address:

The physical, chemical and bioreactivity characteristics of fine particulate matter (PM) collected near (<1 km) two landfill sites and downwind urban sites were investigated. The PM concentrations were significantly higher in winter than summer. Diurnal variations of PM were recorded at both landfill sites. Soot aggregate particles were identified near the landfill sites, which indicated that combustion pollution due to landfill activities was a significant source. High correlation coefficients (r) implied several inorganic elements and water-soluble inorganic ions (vanadium (V), copper (Cu), chloride (Cl), nitrate (NO), sodium (Na) and potassium (K)) were positively associated with wind flow from the landfill sites. Nevertheless, no significant correlations were also identified between these components against DNA damage. Significant associations were observed between DNA damage and some heavy metals such as cadmium (Cd) and lead (Pb), and total Polycyclic Aromatic Hydrocarbons (PAHs) during the summer. The insignificant associations of DNA damage under increased wind frequency from landfills suggested that the PM loading from sources such as regional sources was possibly an important contributing factor for DNA damage. This outcome warrants the further development of effective and source-specific landfill management regulations for particulate matter production control to the city.
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http://dx.doi.org/10.1016/j.chemosphere.2019.05.079DOI Listing
September 2019

Association of wheat chaff derived silica fiber and esophageal cancer in north China.

Ecotoxicol Environ Saf 2019 Aug 15;178:79-85. Epub 2019 Apr 15.

School of Public Health, The University of Hong Kong, 7 Sassoon Road, Hong Kong SAR, China. Electronic address:

Background: Despite decades of research and intervention programs, the epidemic of esophageal squamous cell carcinoma (ESCC) in the Taihang Mountain area of north China has not seen convincing explanation by any risk factor yet and the incidence has not seen a substantial decrease. Based on recently disclosed association of aridity and wheat consumption with esophageal cancer, we revisited the hypothesis of biogenic silica in esophageal cancer development.

Methods: From the archives of the Pathology Department of Heping Hospital, Changzhi Medical College, we selected three pairs of formalin-fixed samples, tumor tissues and distant normal tissues, of three patients operated for ESCC who had no history of workplace exposure to silica dust. Two pairs of dried tissue samples were used for phytolith (silica body) analysis and another pair for microanalysis with Transmission Electron Microscope (TEM).

Results: One of the phytoliths in ESCC tumor tissue was similar to the prickle hair on the surface of wheat bract. In the mineral particles detected in the tumor tissue the predominant elements were Si, Ca, and P, whereas Si signals were not obvious in the distant normal tissue.

Conclusions: The preliminary findings on the detection of phytoliths and the higher than normal Si concentration in ESCC tumor tissue warrants further testing the role of biogenic silica in esophageal cancer.
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http://dx.doi.org/10.1016/j.ecoenv.2019.04.031DOI Listing
August 2019

Air quality changes after Hong Kong shipping emission policy: An accountability study.

Chemosphere 2019 Jul 29;226:616-624. Epub 2019 Mar 29.

School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China. Electronic address:

Background: On July 1st 2015, Hong Kong became the first city in Asia to implement a policy regulating sulfur dioxide (SO) in shipping emissions. We conducted an accountability study assessing the improvement in ambient air quality and estimating the effect on health outcomes of the policy.

Method: We used interrupted time series (ITS) with segmented regression to identify any change in ambient concentrations of SO in contrast to other ambient pollutants (particulate matter <10 μm in diameter (PM), nitrogen dioxide (NO) and ozone (O)) at 10 monitoring stations in Hong Kong from 2010 to 2017. We validated these findings using cumulative sum control (CUSUM) charts. We used a validated risk assessment model to estimate effects of changes in air quality on death for natural causes, cardiovascular and respiratory diseases.

Results: Mean monthly concentrations of SO fell abruptly at the monitoring station closest to the main shipping port (Kwai Chung (KC)) by -10.0 μgm p-value = 0.0004, but not elsewhere. No such changes were evident for the other pollutants (PM, NO, O). CUSUM charts confirmed a change in July 2015. Estimated deaths avoided per year as a result of the policy were 379, 72, 30 for all natural causes, respiratory and cardiovascular diseases respectively.

Conclusion: Implementation of the shipping emission policy in Hong Kong successfully reduced ambient SO, with the potential to reduce mortality. However, to gain full benefits, restrictions on shipping emissions need to be implemented throughout the region.
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http://dx.doi.org/10.1016/j.chemosphere.2019.03.173DOI Listing
July 2019

Vertical monitoring of traffic-related air pollution (TRAP) in urban street canyons of Hong Kong.

Sci Total Environ 2019 Jun 16;670:696-703. Epub 2019 Mar 16.

MRC-PHE Centre for Environment and Health, King's College London, United Kingdom.

Rapid urbanization has significantly increased air pollution especially in urban regions with high traffic volumes. Existing methods for estimating traffic-related air pollution (TRAP) and TRAP-related health impacts are based on two-dimensional modelling. This paper describes a point-based methodology to monitor vertical pollutant concentrations in typical street canyons of Hong Kong. It explains the conceptual design, monitoring strategy and selection criteria for a limited number of receptor locations in street canyons to undertake field measurements for both outdoor exposure and indoor infiltration. It also expounds on the limitations and complications associated with field instrumentation and retention of participating home units. The empirical results were applied on the building infiltration efficiencies assessment. It is concluded that the cost-effective field methodology developed in this paper expects to strike a balance between exposure error and limited data locations. These findings will have important implications in future monitoring design of vertical TRAP exposure to support health studies.
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http://dx.doi.org/10.1016/j.scitotenv.2019.03.224DOI Listing
June 2019

Increased susceptibility to heat for respiratory hospitalizations in Hong Kong.

Sci Total Environ 2019 May 16;666:197-204. Epub 2019 Feb 16.

School of Public Health, The University of Hong Kong, Hong Kong, China. Electronic address:

Background: Emerging studies have shown temperature-mortality association is changing over time, but little is known about the temporal changes of the temperature-morbidity association.

Objectives: We aimed to evaluate the temporal variations in both temperature-respiratory hospitalizations associations and temperature-related attributable risks in Hong Kong.

Methods: We collected 17-year time-series data on daily ambient temperature and emergency hospital admissions for respiratory diseases between 2000 and 2016 in Hong Kong. Quasi-Poisson regression with a time-varying distributed lag nonlinear model was used to estimate the year-specific association between temperature and respiratory hospitalizations [total respiratory, pneumonia, and chronic obstructive pulmonary disease (COPD)] and the year-specific attributable fraction (AF) for heat and cold (defined as above/below the optimum temperature, respectively).

Results: Heat-related risks and AFs increased continuously for total respiratory, pneumonia and COPD hospitalizations during the past 17 years, respectively. Cold-hospitalization associations and cold-related AFs showed heterogeneous patterns, showing a decreasing trend for pneumonia but a general increasing trend for COPD for both the associations and AFs. The total temperature-related AFs remained stable for total respiratory (p for trend = 0.136) and pneumonia (p for trend = 0.406), but showed an increasing trend for COPD (p for trend < 0.001) from 10% (95% empirical CI: 2%, 17%) in 2000 to 17% (95% empirical CI: 11%, 22%) in 2016.

Conclusions: Our findings indicate an increased susceptibility to heat but a decreased susceptibility to cold for respiratory hospitalizations during the past 17 years. The overall temperature-related hospitalization burden for respiratory diseases was generally stable in Hong Kong.
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http://dx.doi.org/10.1016/j.scitotenv.2019.02.229DOI Listing
May 2019

Five-year lung cancer mortality risk analysis and topography in Xuan Wei: a spatiotemporal correlation analysis.

BMC Public Health 2019 Feb 11;19(1):173. Epub 2019 Feb 11.

Department of Thoracic Surgery I, Cancer Research Institute of Yunnan Province, The Third Affiliated Hospital of Kunming Medical University (Yunnan Cancer Hospital), Kunming, Yunnan, China.

Background: In Xuan Wei, China, the lung cancer mortality rate is rising significantly more than that of the nation overall. However, it remains unclear 1) if improved diagnosis can just partially explain this observation and how other local risk factors may be correlated with the lung cancer mortality rate and 2) how the lung cancer mortality rates differ within Xuan Wei and how these spatiotemporal patterns are linked with local risk factors. To increase etiological knowledge, this study evaluated the spatial and temporal distributions of the health effects (the lung cancer mortality rates) from 2011 to 2015.

Methods: Four steps of spatial analysis were applied, as follows: 1) hotspot analysis to determine the geographical patterns of lung cancer mortality, 2) spatially-weighted sum to identify areas with higher health risks, 3) bivariate statistical analysis to assess the overall correlation between coal mines and lung cancer mortality, and 4) geographically-weighted regression to test for correlations among different towns within Xuan Wei.

Results: Women had higher lung cancer mortality rates than those in men, with an increasing trend in both sexes over time. The incidence rates in Laibin Town were the highest in Xuan Wei every year. Over the 5-year study period, the lung cancer mortality was increasingly concentrated in Laibin, Shuanglong, and Longchang, where the smoky coal mines are most concentrated. The population-level health risks from the coal mine in Xuan Wei were mapped and divided into five types of risk areas (Type I - Type IV). Correlation analysis revealed that there was no significant correlation between lung cancer mortality as a whole and coal mine distribution during the 5-year study period. However, the geographically-weighted regression revealed a stronger correlation in medium (Type III) and second-lowest (Type IV) health risks.

Conclusions: Xuan Wei lung cancer mortality has increased continuously since the third national retrospective surveys on the causes of death by the Ministry of Health of the People's Republic of China (2004-2005), especially for local women and residents over 35 years of age. Geographically, lung cancer in Xuan Wei showed unique spatiotemporal clustering. The local lung cancer mortality was significantly correlated with the smoky coal mine geographically. Some specific towns (Laibin, Shuanglong, and Longchang) within Xuan Wei manifested high correlations between lung cancer mortality and coal mines. The effects of coal mines on lung cancer mortality rates also spread geographically outward from these areas. Public health concern regarding lung cancer in Xuan Wei should prioritize higher-risk towns surrounded by smoking coal mines. Intervention strategies for particular toxic coal types require further studies on their chemical characteristics and mechanisms of carcinogenesis. Additional studies are also warranted to systematically examine the local environmental health risks related to coal industries and combustion air pollution and eventually to conduct early screening of lung cancer for local people who are more exposed to smoky coal in high-risk areas.
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http://dx.doi.org/10.1186/s12889-019-6490-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6371498PMC
February 2019

Short-term and long-term exposures to fine particulate matter constituents and health: A systematic review and meta-analysis.

Environ Pollut 2019 Apr 21;247:874-882. Epub 2018 Dec 21.

School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China. Electronic address:

Background: Fine particulate matter (Particulate matter with diameter ≤ 2.5 μm) is associated with multiple health outcomes, with varying effects across seasons and locations. It remains largely unknown that which components of PM are most harmful to human health.

Methods: We systematically searched all the relevent studies published before August 1, 2018, on the associations of fine particulate matter constituents with mortality and morbidity, using Web of Science, MEDLINE, PubMed and EMBASE. Studies were included if they explored the associations between short term or long term exposure of fine particulate matter constituents and natural, cardiovascular or respiratory health endpoints. The criteria for the risk of bias was adapted from OHAT and New Castle Ottawa. We applied a random-effects model to derive the risk estimates for each constituent. We performed main analyses restricted to studies which adjusted the PM mass in their models.

Results: Significant associations were observed between several PM constituents and different health endpoints. Among them, black carbon and organic carbon were most robustly and consistently associated with all natural, cardiovascular mortality and morbidity. Other potential toxic constituents including nitrate, sulfate, Zinc, silicon, iron, nickel, vanadium, and potassium were associated with adverse cardiovascular health, while nitrate, sulfate and vanadium were relevant for adverse respiratory health outcomes.

Conclusions: Our analysis suggests that black carbon and organic carbon are important detrimental components of PM, while other constituents are probably hazardous to human health. However, more studies are needed to further confirm our results.
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http://dx.doi.org/10.1016/j.envpol.2018.12.060DOI Listing
April 2019

A possible role of biogenic silica in esophageal cancer in North China?

Environ Sci Pollut Res Int 2019 Mar 28;26(8):8340-8343. Epub 2019 Jan 28.

School of Public Health, The University of Hong Kong, 7 Sassoon Road, Hong Kong, SAR, China.

Certain areas in North China have the highest incidence of esophageal squamous cell carcinoma (ESCC) in the world, which has not seen convincing explanation by any risk factor yet. Biogenic silica in millet bran was linked to ESCC in the early 1980s but the hypothesis was largely dismissed because of the lack of geographic correlation between millet consumption and ESCC. Later epidemiological studies disclosed the linkage of wheat consumption in North China to ESCC instead. Now, we hypothesize silica phytoliths (silicified bodies that have definite shapes) from wheat chaff are a major etiologic factor of ESCC in this region. This hypothesis is supported by the potentially high abundance of silica phytoliths on the bracts of wheat (Triticum aestivum) in North China due to favorable Si-accumulation genotype, arid climate, and siallitic soil with bioavailable Si. These silica phytoliths can contaminate wheat flour and cause repeated local injuries in the esophagus and stimulate proliferation by providing anchorage.
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http://dx.doi.org/10.1007/s11356-019-04332-wDOI Listing
March 2019

Bituminous coal combustion and Xuan Wei Lung cancer: a review of the epidemiology, intervention, carcinogens, and carcinogenesis.

Arch Toxicol 2019 03 16;93(3):573-583. Epub 2019 Jan 16.

Li Ka Shing Faculty of Medicine, School of Public Health, The University of Hong Kong, 7 Sassoon Road, Pokfulam, Hong Kong SAR, China.

Indoor air pollution from bituminous coal combustion has been linked to the extremely high lung cancer rates of nonsmoking women in Xuan Wei County, Yunnan Province, China. Venting the smoke outdoors by installing chimneys was found to be effective at reducing the lung cancer risk in a cohort study of 21,232 farmers in central Xuan Wei. However, the lung cancer mortality rates in all 1.2 million residents of Xuan Wei have been increasing dramatically over the last four decades. It was higher than that in Yunnan Province and China overall, with significant heterogeneities in the geographic patterns of Xuan Wei. Intervention measures targeting certain types of coal or certain carcinogenic components in coal smoke need to be explored. To inform targeted intervention policies, it is essential to pinpoint the specific substance (particulate matter, organic extract, PAHs, free radicals, crystalline silica, and inorganic matter) that might account for the carcinogenicity of bituminous coal smoke. Exploring the underlying carcinogenesis mechanisms would also contribute to the intervention and control of the lung cancer epidemic in Xuan Wei, China. Here we review the suspected carcinogens and carcinogenesis mechanisms and discuss future research directions towards a better understanding of the etiology of lung cancer in Xuan Wei, China.
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http://dx.doi.org/10.1007/s00204-019-02392-yDOI Listing
March 2019

Effects of ambient benzene and toluene on emergency COPD hospitalizations: A time series study in Hong Kong.

Sci Total Environ 2019 Mar 4;657:28-35. Epub 2018 Dec 4.

School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, China. Electronic address:

Background: Although numerous studies have demonstrated that the criteria air pollutants increased the risk of exacerbation of chronic obstructive pulmonary disease (COPD), few have explored the effects of ambient benzene and toluene on COPD.

Objective: This study aimed to evaluate the short-term effects of ambient benzene and toluene on emergency COPD (eCOPD) hospitalizations.

Methods: We obtained daily mean and maximum concentrations of benzene and toluene during April 1, 2011 - December 31, 2014 from the Hong Kong Environmental Protection Department, and daily counts of eCOPD hospitalizations from the Hospital Authority. Generalized additive distributed lag models were used to estimate the percentage excess risk (ER%) of eCOPD hospitalizations per interquartile range (IQR) increase in ambient benzene and toluene.

Results: The ER% estimates of eCOPD hospitalizations post cumulative exposure of up to two days were 2.62% (95%CI: 0.17% to 5.13%) and 1.42% (0.16% to 2.69%), for per IQR increase of daily mean benzene (1.4μg/m) and toluene (4.6μg/m), respectively. People below the age of 65 had a significantly higher risk of eCOPD hospitalizations associated with daily maximum toluene than the elderly.

Conclusions: Ambient benzene and toluene might be environmental stressors for acute exacerbations of COPD in the Hong Kong population.
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http://dx.doi.org/10.1016/j.scitotenv.2018.12.015DOI Listing
March 2019

Lung cancer risk by geologic coal deposits: A case-control study of female never-smokers from Xuanwei and Fuyuan, China.

Int J Cancer 2019 06 15;144(12):2918-2927. Epub 2019 Jan 15.

Occupational and Environmental Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Rockville, MD, USA.

Coal types vary around the world because of geochemical differences in their source deposits; however, the influence of coal emissions from different deposits on human health remains unexplored. To address this issue, we conducted the first study of the relationship between coal use from various deposits and lung cancer risk in Xuanwei and Fuyuan, counties in China where lung cancer rates are among the highest in the world among female never-smokers due to use of bituminous ("smoky") coal for heating and cooking. We conducted a population-based case-control study of 1031 lung cancer cases and 493 controls among never-smoking women in Xuanwei and Fuyuan. Logistic regression models were used to estimate associations between coal use from various deposits across the lifecourse and lung cancer risk. There was substantial heterogeneity in risks by coal deposit (p = 7.8E-05). Compared to non-smoky coal users, risks by smoky coal deposit ranged from OR = 7.49 (95% CI: 3.43-16.38) to OR = 33.40 (95% CI: 13.07-85.34). Further, women born into homes that used smoky coal and subsequently changed to non-smoky coal had a higher risk (OR = 10.83 (95% CI: 4.61-25.46)) than women born into homes that used non-smoky coal and changed to smoky coal (OR = 4.74 (95% CI: 2.03-11.04, p = 0.04)). Our study demonstrates that various sources of coal have considerably different impact on lung cancer in this population and suggests that early-life exposure to carcinogenic emissions may exert substantial influence on health risks later in life. These factors should be considered when evaluating the health risks posed by exposure to coal combustion emissions.
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http://dx.doi.org/10.1002/ijc.32034DOI Listing
June 2019