Hong Chen

• doctor of science
• Bohai University

Background Evidence suggests the existence of nonlinearity in the relationship between long-term fine particulate matter (PM 2.5 ) and mortality, and the methods to flexibly incorporate nonlinearity can be improved. To heuristically evaluate the necessity of incorporating machine-learning algorithms, we compared the benefit of reducing long-term PM...

BACKGROUND AND AIM[|]PM2.5 is a mixture of multiple gaseous and chemical components with varying levels of concentration and toxicity across time. Quantile G-computation (QGcomp), one of the available multipollutant methods, can estimate the causal joint effect of time-fixed environmental mixtures. However, multipollutant methods are rarely applied...

Objective Exposure to fine particulate matter (PM2.5) has been linked to many diseases. However, it remains unclear which PM2.5 chemical components for these diseases, including rheumatoid arthritis (RA), are more harmful. This study aimed to assess potential associations between PM2.5 components and RA and quantify the individual effects of each c...

Rationale: Outdoor fine particulate air pollution (PM2.5) contributes to millions of deaths around the world each year, but much less is known about the long-term health impacts of other particulate air pollutants including ultrafine particles (a.k.a. nanoparticles) which are in the nanometer size range (<100 nm), widespread in urban environments,...

Background: Past investigations of air pollution and systemic autoimmune rheumatic diseases (SARDs) typically focused on individual (not mixed) and overall environmental emissions. We assessed mixtures of industrial emissions of fine particulate matter (PM2.5), nitrogen dioxide (NO2), and sulfur dioxide (SO2) and SARDs onset in Ontario, Canada. M...

Background: Numerous epidemiological studies have documented the adverse health impact of long-term exposure to fine particulate matter [particulate matter ≤2.5μm in aerodynamic diameter (PM2.5)] on mortality even at relatively low levels. However, methodological challenges remain to consider potential regulatory intervention's complexity and prov...

Background Numerous epidemiological studies have documented the adverse health impact of long-term exposure to fine particulate matter (PM2.5) on mortality even at relatively low levels. However, methodological challenges remain to consider potential regulatory intervention's complexity and provide actionable evidence on the predicted benefits of i...

Differential participation in observational cohorts may lead to biased or even reversed estimates. In this article, we describe the potential for differential participation in cohorts studying the etiologic effects of long-term environmental exposures. Such cohorts are prone to differential participation because only those who survived until the st...

Emissions of fine particulate matter (PM 2.5 ) from human activities have been linked to substantial disease burdens, but evidence regarding how reducing PM 2.5 at its sources would improve public health is sparse. We followed a population-based cohort of 2.7 million adults across Canada from 2007 through 2016. For each participant, we estimated an...

Background Long‐term exposure to outdoor fine particulate matter (PM 2.5 ) is the leading environmental risk factor for premature mortality worldwide. Characterizing important pathways through which PM 2.5 increases individuals' mortality risk can clarify the PM 2.5 –mortality relationship and identify possible points of interventions. Recent evide...

Background Exposure to fine particulate matter (PM2.5) is associated with adverse health outcomes but communities are not randomly exposed to PM2.5. Previous cross-sectional environmental injustice analyses in Canada found disproportionately higher exposure to PM2.5 in low-income populations, visible minorities and immigrants. Beyond static surveil...

Objectives To estimate associations between fine particulate matter (PM2.5) and ozone and the onset of systemic autoimmune rheumatic diseases (SARDs). Methods An open cohort of over 6 million adults was constructed from provincial physician billing and hospitalization records between 2000 and 2013. We defined incident SARD cases (SLE, Sjogren’s sy...

Background: The tremendous global health burden related to COVID-19 means that identifying determinants of COVID-19 severity is important for prevention and intervention. We aimed to explore long-term exposure to ambient air pollution as a potential contributor to COVID-19 severity, given its known impact on the respiratory system. Methods: We u...

Background Ambient air pollution is thought to contribute to increased risk of COVID-19, but the evidence is controversial. Objective To evaluate the associations between short-term variations in outdoor concentrations of ambient air pollution and COVID-19 emergency department (ED) visits. Methods We conducted a case-crossover study of 78 255 COV...

Background: The association between fine particulate matter (PM2.5) and mortality widely differs between as well as within countries. Differences in PM2.5 composition can play a role in modifying the effect estimates, but there is little evidence about which components have higher impacts on mortality. Methods: We applied a two-stage analysis on...

Objective: To investigate the association between changes in long term residential exposure to ambient fine particulate matter (PM2.5) and premature mortality in Canada. Design: Population based quasi-experimental study. Setting: Canada. Participants: 663 100 respondents to the 1996, 2001, and 2006 Canadian censuses aged 25-89 years who had...

Field studies have shown that dense tree canopies and regular tree arrangements reduce noise from a point source. In urban areas, noise sources are multiple and tree arrangements are rarely dense. There is a lack of data on the association between the urban tree canopy characteristics and noise in complex urban settings. Our aim was to investigate...

We used a large national cohort in Canada to assess the incidence of acute myocardial infarction (AMI) and stroke hospitalizations in association with long-term exposure to fine particulate matter (PM2.5), nitrogen dioxide (NO2), and ozone (O3). The study population comprised 2.7 million respondents from the 2006 Canadian Census Health and Environm...

Background Several studies have found positive associations between outdoor fine particulate air pollution (≤2.5 μm, PM2.5) and childhood asthma incidence. However, the impact of PM2.5 composition on children’s respiratory health remains uncertain. Objective We examined whether joint exposure to PM2.5 mass concentrations and its major chemical com...

Background: Air pollution has been associated with increased mortality. However, updated evidence from cohort studies with detailed information on various risk factors is needed, especially in regions with low air pollution levels. We investigated the associations between long-term exposure to air pollution and mortality in a prospective cohort....

Metal components in fine particulate matter (PM2.5) from nontailpipe emissions may play an important role in underlying the adverse respiratory effects of PM2.5. We investigated the associations between long-term exposure to iron (Fe) and copper (Cu) in PM2.5 and their combined impact on reactive oxygen species (ROS) generation in human lungs, and...

Objective We assessed long-term incidence and prevalence trends of dementia and parkinsonism across major ethnic and immigrant groups in Ontario. Methods Linking administrative databases, we established two cohorts (dementia 2001–2014 and parkinsonism 2001–2015) of all residents aged 20 to 100 years with incident diagnosis of dementia (N = 387,937...

Background Exposure to fine particulate (PM2.5) air pollution is associated with increased cardiovascular disease (CVD), but less is known about its specific components, such as metals originating from non-tailpipe emissions. We investigated the associations of long-term exposure to metal components [iron (Fe) and copper (Cu)] in PM2.5 with CVD inc...

Rationale: Current evidence on the relationship between long-term exposure to air pollution and new onset of chronic lung disease is inconclusive. Objective: To examine associations of incident chronic obstructive pulmonary disease (COPD) and adult-onset asthma with past exposure to fine particulate matter (PM2.5), nitrogen dioxide (NO2), ozone...

INTRODUCTION: Environmental factors related to urbanization and industrialization are believed to be involved in inflammatory bowel disease (IBD) development, but no study has looked at the association between greenspace and IBD. METHODS: We conducted a retrospective cohort study using linked population-based health administrative and environmen...

Background: Ambient air pollution has been associated with childhood cancer. However, little is known about the possible impact of ambient ultrafine particles (<0.1 μm) (UFPs) on childhood cancer incidence. Objective: This study aimed to evaluate the association between prenatal and childhood exposure to UFPs and development of childhood cancer....

Background: Epidemiological evidence for the association between traffic-related noise and the incidence of major cardiovascular events such as acute myocardial infarction (AMI) and congestive heart failure (CHF) is inconclusive, especially in North America. Objectives: We evaluated the associations between long-term exposure to road traffic noi...

Background: Living in greener areas of cities was linked to increased physical activity levels, improved mental well-being, and lowered harmful environmental exposures, all of which may affect human health. However, whether living in greener areas may be associated with lower risk of cardiovascular disease incidence, progression, and premature mor...

Background High-income nations have the highest rates of inflammatory bowel disease (IBD). The incidence of pediatric-onset IBD is increasing faster than IBD diagnosed in older individuals. Previous epidemiological studies have shown that air pollution might be a risk factor for development of earlier-onset IBD, but results remain mixed. Objective...

Introduction It is unknown whether urban green space is associated with reduced risk of major neurological conditions, especially dementia and stroke. Methods Retrospective, population-based cohorts were created for each study outcome, including 1.7 and 4.3 million adults in Ontario, Canada for dementia and stroke, respectively. Residential green...

Background Exposure to road traffic noise has been linked to cardiometabolic complications, such as elevated blood pressure and glucose dysregulation. However, epidemiologic evidence linking road traffic noise to diabetes mellitus and hypertension remains scarce. We examined associations between road traffic noise and the incidence of diabetes mell...

Past health impact assessments of ambient fine particles (PM2.5) have generally considered mass concentration only, despite PM2.5 is a heterogeneous mixture. Given constant changes in the concentration and composition of atmospheric aerosol, considerable uncertainty exists as to whether the current focus on PM2.5 mass or individual components may f...

Background: Studies have reported increasing incidence rates of paediatric diabetes, especially among those aged 0-5 years. Epidemiological evidence linking ambient air pollution to paediatric diabetes remains mixed. Objective: This study investigated the association between maternal and early-life exposures to common air pollutants (NO2, PM2.5,...

The interaction mechanisms of chrysene with bovine serum albumin (BSA) were studied by multispectroscopy and molecular docking method. The quenching mechanism, binding constants, thermodynamic parameters and binding force of chrysene with BSA were investigated. The results indicated that the fluorescence of BSA was quenched by chrysene through a st...

Purpose: Growing evidence implicates ambient air pollutants in the development of major chronic diseases and premature mortality. However, epidemiologic evidence linking air pollution to diabetes remains inconclusive. This study sought to determine the relationships between selected air pollutants (nitrogen dioxide [NO2], fine particulate matter [...

Background: Cardiovascular malformations account for nearly one-third of all congenital anomalies, making these the most common type of birth defects. Little is known regarding the influence of ambient ultrafine particles (<0.1 μm) (UFPs) on their occurrence. Objective: This population-based study examined the association between prenatal exposu...

Long-term exposure to ambient air pollution has been linked to cardiovascular mortality, but the associations with incidence of major cardiovascular diseases are not fully understood, especially at low concentrations. We aimed to investigate the associations between exposure to fine particulate matter (PM2.5), nitrogen dioxide (NO2), ozone (O3), re...

Background: Although growing evidence links air pollution to stroke incidence, less is known about the effect of air pollution on atrial fibrillation (AF), an important risk factor for stroke. Objectives: We assessed the associations between air pollution and incidence of AF and stroke. We also sought to characterize the shape of pollutant-disea...

Lung and female breast cancers are highly prevalent worldwide. Although the association between exposure to ambient fine particulate matter (PM2.5) and lung cancer has been recognized, there is less evidence for associations with other common air pollutants such as nitrogen dioxide (NO2) and ozone (O3). Even less is known about potential associatio...

Background: Evidence suggests a link between air pollution and dementia. Cardiovascular disease (CVD) may be a potential determinant of dementia. This motivated us to quantify the contribution of CVD to the association between air pollution and dementia. Methods: A cohort of Canadian-born residents of Ontario, who participated in the 1996-2003 C...

Rationale: Little is known regarding the impact of ambient ultrafine particles (UFPs; <0.1 μm) on childhood asthma development. Objectives: To examine the association between prenatal and early postnatal life exposure to UFPs and development of childhood asthma. Methods: A total of 160,641 singleton live births occurring in the City of Toronto, Can...

Objectives: We assessed trends in the incidence, prevalence, and post-diagnosis mortality of parkinsonism in Ontario, Canada over 18 years. We also explored the influence of a range of risk factors for brain health on the trend of incident parkinsonism. Methods: We established an open cohort by linking population-based health administrative data...

Exposure to ambient fine particulate matter (PM2.5) is a major global health concern. Quantitative estimates of attributable mortality are based on disease-specific hazard ratio models that incorporate risk information from multiple PM2.5 sources (outdoor and indoor air pollution from use of solid fuels and secondhand and active smoking), requiring...

Although long-term exposure to traffic-related air pollutants such as nitrogen dioxide (NO2) has been linked to cardiovascular mortality, little is known about the association of ultrafine particles (UFPs) with incidence of major cardiovascular events. We conducted a population-based cohort study to assess the associations of chronic exposure to UF...

Background: Despite recent studies linking air pollution to neurodegenerative illness, evidence relating air pollution and Parkinson's disease (PD) remains scarce. We conducted a population-based cohort study in Ontario, Canada, to determine the association between air pollution and incident PD. Methods: Using health administrative databases, we...

BACKGROUND: Increasing evidence suggests that residential exposures to natural environments,such as green spaces, are associated with many health benefits. Only a single study has examined the potential link between living near water and mortality. OBJECTIVE: We sought to examine whether residential proximity to large,natural water features(e.g.,la...

A technique of diffusive gradients in thin films with ciprofloxacin‐molecularly imprinted polymers as the binding agent was developed for in situ selective sampling and measurement of ciprofloxacin in water. The ciprofloxacin uptake by the method increased linearly with time (r² = 0.998) with a recovery of 96.8% in synthetic solution. The method pe...

Background: Increasing evidence suggests that residential exposures to natural environments, such as green spaces, are associated with many health benefits. Only a single study has examined the potential link between living near water and mortality. Objective: We sought to examine whether residential proximity to large, natural water features (e...

Background: Prenatal exposure to fine particulate matter air pollution with aerodynamic diameter ≤2.5 μm (PM2.5) has been associated with preterm delivery and low birth weight (LBW), but few studies have examined possible effect modification by oxidative potential. Objectives: The aim of this study was to evaluate if regional differences in the...

Background: Evidence of the adverse neurological effects of exposure to ambient air pollution is emerging, but little is known about its effect on the development of multiple sclerosis (MS), the most common autoimmune disease of the central nervous system. Objectives: To investigate the associations between MS incidence and long-term exposures t...

Introduction: Studies suggest living in a more walkable neighborhood may protect against cardiovascular disease risk factors such as hypertension (HTN) and diabetes mellitus (DM) by encouraging physical activity. Walkable neighborhoods, however, often carry higher levels of traffic-related air pollution. Little is known regarding whether synergisti...

Objective: We sought to better understand the reasons for increasing prevalence of multiple sclerosis (MS) by studying prevalence in relation to incidence, mortality rates, sex ratio, and geographic distribution of cases. Methods: We identified MS cases from 1996 to 2013 in Ontario, Canada, by applying a validated algorithm to health administrat...

Road traffic noise can adversely impact the health of city residents, particularly when it occurs at night. The objective of this study was to evaluate nighttime traffic ambient noise in Toronto, Canada using measured and model-estimated noise levels. Road traffic noise was measured at 767 locations over three seasonal sampling campaigns between Ju...

Perinatal exposure to ambient air pollution has been associated with childhood asthma incidence; however, less is known regarding the potential effect modifiers in this association. We examined whether maternal and infant characteristics modified the association between perinatal exposure to air pollution and development of childhood asthma. 761 17...

Background: Previous studies reported that long-term exposure to traffic-related air pollution may increase the incidence of hypertension and diabetes. However, little is known about the associations of ultrafine particles (≤0.1 μm in diameter) with these two conditions. Methods: We conducted a population-based cohort study to investigate the as...

Background Ambient air pollution is a major health risk globally. To reduce adverse health effects on days when air pollution is high, government agencies worldwide have implemented air quality alert programmes. Despite their widespread use, little is known about whether these programmes produce any observable public-health benefits. We assessed th...

Objective To assess the associations between ambient temperatures and hospitalisations for coronary heart disease (CHD) and stroke. Methods Our study comprised all residents living in Ontario, Canada, 1996–2013. For each of 14 health regions, we fitted a distributed lag non-linear model to estimate the cold and heat effects on hospitalisations fro...

Background Findings from published studies suggest that exposure to and interactions with green spaces are associated with improved psychological wellbeing and have cognitive, physiological, and social benefits, but few studies have examined their potential effect on the risk of mortality. We therefore undertook a national study in Canada to examin...

Introduction: Emerging studies have implicated air pollution in the neurodegenerative processes. Less is known about the influence of air pollution, especially at the relatively low levels, on developing dementia. We conducted a population-based cohort study in Ontario, Canada, where the concentrations of pollutants are among the lowest in the wor...

Background: Large cohort studies have been used to characterise the association between long-term exposure to fine particulate matter (PM2.5) air pollution with non-accidental, and cause-specific mortality. However, there has been no consensus as to the shape of the association between concentration and response. Methods: To examine the shape of...

Background: Little is known about the long-term health effects of ambient ultrafine particles (<0.1 μm) (UFPs) including their association with respiratory disease incidence. In this study, we examined the relationship between long-term exposure to ambient UFPs and the incidence of lung cancer, adult-onset asthma, and chronic obstructive pulmonary...

Background: There are increasing concerns regarding the role of exposure to ambient air pollution during pregnancy in the development of early childhood cancers. Objective: This population based study examined whether prenatal and early life (<1year of age) exposures to ambient air pollutants, including nitrogen dioxide (NO2) and particulate mat...

Background: Emerging evidence suggests that living near major roads might adversely affect cognition. However, little is known about its relationship with the incidence of dementia, Parkinson's disease, and multiple sclerosis. We aimed to investigate the association between residential proximity to major roadways and the incidence of these three n...

The effectiveness of regulatory actions designed to improve air quality is often assessed by predicting changes in public health resulting from their implementation. Risk of premature mortality from long-term exposure to ambient air pollution is the single most important contributor to such assessments and is estimated from observational studies ge...

Background: Daily changes in aeroallergens during pregnancy could trigger early labor, but few investigations have evaluated this issue. This study aimed to investigate the association between exposure to aeroallergens during the week preceding birth and the risk of early delivery among preterm and term pregnancies. Methods: We identified data o...

Purpose: To examine the impact of ambient temperature on the incidence of emergency department admissions for acute renal colic and the potential influence demographics and comorbid conditions may have on this. Methods: We conducted a population-based time series analysis using linked healthcare databases in Ontario, Canada that included all res...