Occupational Exposure to Ambient Air Pollution: At-Risk Worker Groups, Regulatory and Research Needs An Official American Thoracic Society Workshop Report

Roles of pollution in the prevalence and exacerbations of allergic diseases in Asia

Air Pollution and Coronary Risk in Kidney Transplant Recipients

ObjectivesTo assess the respiratory health effect of city ambient air pollutants on transit and non-transit workers and compare such effects by transportation mode, occupational exposure and sociodemographic characteristics of participants.DesignCross-sectional,...

Air pollution is one of the major causes of mortality and morbidity in the world today. World Health Organization (WHO) data show that almost all of the global population (99%) breathe air that exceeds WHO guideline limits and contains high levels of pollutants, with low- and middle-income countries suffering most from air pollution exposure. In China, the largest developing country, the poor air quality is primarily attributed to the rapid economic expansion the country experienced since the reform and opening-up in 1978, resulting in a drastic increase in coal-powered industrial production and electricity demand, as well as an exponential rise in private vehicles. Although there has been continuous air quality improvement following a series of stringent control policies, air pollution remains an important public health threat in China. The Global Burden of Disease Study estimated that in 2019, air pollution was responsible for 1.85 million deaths in China[1]. Meanwhile, non-communicable diseases (NCDs), such as cardiovascular disease and cancer, have placed much more disease burden on the population than ever[2]. It has been estimated that cardiovascular disease is now the leading cause of death in the Chinese population of adults 40 years of age and older, accounting for around 40% of total mortality. A growing body of human and animal evidence has led to a concern about the potential deleterious effects of ambient air pollution on the cardiovascular system[3,4]. For example, using the largest nationwide data in 272 Chinese cities, Chen et al. reported that a 10 μg/m3 increment of PM2.5 was associated with an increase of 0.27% in cardiovascular mortality. Similarly, in 652 cities of 24 countries, Liu et al. reported that an increase of 10 μg/m3 increment of PM2.5 was associated with increases of 0.36% in daily cardiovascular mortality[5]. The mixture of air pollutants may adversely affect the cardiovascular system directly and indirectly[6]. Direct effects may occur via agents that readily cross the pulmonary epithelium into the circulation, such as ultra-fine particles (UFPs), soluble constituents of particles (e.g., sulfate and nitrate), and gaseous pollutants (e.g., nitrogen oxides). Indirect effects may occur via induction of pulmonary inflammation and oxidative stress, leading to systemic inflammation and endothelial dysfunction. Although the adverse cardiovascular effects of air pollution have been documented in China, questions remain to be solved in human-based studies, especially for a stronger causal inference[7]. In this issue, we invited esteemed colleagues from some of the most reputable institutions in China and the United States, including Yale University, the Chinese Center for Disease Control and Prevention, Fudan University, and Chinese Academy of Medical Sciences and Peking Union Medical College to report their latest findings on air pollution and cardiovascular disorders. Their intriguing findings underscore the importance of understanding the health impacts of air pollution, particularly in China where the problem is especially severe due to rapid industrialization and urbanization. Ban et al. investigated the linear and non-linear patterns for the association between PM2.5 and acute incidence of myocardial infarction (MI) based on a multi-county registry dataset. They evaluated the reduction of premature MI incidence under different pollution control objectives in China[8]. This study provided valuable insights into the impact of PM2.5 on cardiovascular health on a national scale, and its findings can help inform policies aimed at reducing the burden of cardiovascular disease in China. Du et al. investigated the health effects of short-term exposure to PM2.5 from agricultural sources on acute MI onset using a nationwide database in China[9]. The study found that exposure to agricultural PM2.5 was associated with an increased risk of acute MI, highlighting the need for more research on estimating the adverse health effects of different air pollution sources. The study conducted by Jiang et al. explored the impacts of PM2.5 and PM2.5–10 on the onset of stable and unstable angina at an hourly temporal resolution, adjusting for key confounders[10]. They suggest that life-threatening cardiovascular disease risk from transient exposure to air pollution must be considered by healthcare professionals including cardiologists and patient caregivers to avoid negative cardiorespiratory outcomes. Finally, Zhou et al. reviewed available evidence quantifying the relationship between exposure to ambient gaseous and particulate air pollutants and cardiovascular symptoms[11]. The study found that exposure to air pollution was associated with a wide range of cardiovascular symptoms, including heart failure, arrhythmias, and hypertension. Although the findings above confirm that air pollution contributes to the cardiovascular disorders in China, several questions or challenges remain to be solved in human-based studies, especially for a stronger causal inference. Although some recent prospective cohort studies in China have examined the long-term effects of air pollution on cardiovascular mortality or morbidity[12], cohort studies are still lacking in examining a full spectrum of cardiometabolic diseases. Most Chinese studies on air pollution and cardiovascular health are observational in nature, thus limiting the power of causal inference. Accountability studies that evaluate long-term health benefits of clean air policies and intervention studies that reduce individual exposure may help to establish a causal relationship between air pollution and cardiovascular health[13]. The application of the difference-in-differences approach and randomized crossover design in intervention studies have been shown to further improve the causality[14]. Controlled-exposure human trials are particularly useful to establish the biological causation for the adverse cardiovascular effects of air pollution[15]. As research on the relationship between air pollution and cardiovascular health in the Chinese population continues to evolve, it is important to remember the many questions and challenges that remain. One area requiring further investigation is the lifetime course of cardiovascular damage effects, which could be addressed through prospective cohort studies. By following a large cohort of individuals over time, researchers can better understand how air pollution exposure affects the development and progression of cardiovascular diseases over the course of an individual's life. In addition to clarifying the long-term effects of air pollution on cardiovascular health, it is also important to examine the relevance of cumulative exposure. This requires not only tracking the levels of air pollution that individuals are exposed to over time but also considering how exposure to other risk factors, such as smoking, physical activities, green space, or a poor diet, may interact with air pollution exposure to affect cardiovascular health outcomes. By taking a more comprehensive approach to understanding the health impacts of air pollution, researchers can help to identify the most vulnerable populations and periods and develop more effective public health interventions to mitigate the negative health effects of air pollution. Another crucial area for future research is the investigation of genetic–environment interactions in relation to air pollution exposure and cardiovascular health. While genetic factors have been shown to play a role in the development of cardiovascular disease, their interaction with environmental factors such as air pollution is still poorly understood. By identifying genetic variations that may increase an individual's susceptibility to the negative health effects of air pollution, researchers can help to develop more personalized approaches to the prevention and treatment of cardiovascular diseases. Finally, it is important to establish the pathophysiologic link between air pollution and cardiometabolic diseases in the Chinese population. This requires identifying the specific mechanisms by which air pollution exposure leads to cardiovascular disease and understanding how these mechanisms may differ across different population subgroups. By gaining a more detailed understanding of the biological pathways that link air pollution exposure to cardiovascular disease, researchers can help to develop more targeted and effective interventions to mitigate the negative health effects of air pollution. Beyond these research priorities, there is clear evidence showing that climate change poses significant health risks to the population, and population health risks due to environmental factors under changing climate will become more severe in the future[16]. Air quality is closely linked to the earth's climate and ecosystems globally, as many of the air pollutants and greenhouse gases share the same sources (e.g., combustion of fossil fuels). Therefore, policies to reduce air pollution offer a win-win strategy for both climate and health, lowering the burden of disease attributable to air pollution, and contributing to the near- and long-term mitigation of climate change can be accomplished at the same time. Therefore, air pollution, climate change, and population health need to be considered simultaneously. Meanwhile, health risks from environmental factors will persist under climate change, and gaps in research evidence that may support population adaptation should be filled. In addition, innovative technologies and methodologies that may be applied to population health interventions should be developed. In summary, consideration of the health impacts and coping strategies of air pollution and climate change can help the government move forward towards sustainable development with appropriate urgency, reducing the disease burden and promoting a more healthy and sustainable future for all. CONFLICTS OF INTEREST STATEMENT Haidong Kan is an Editorial Board member of Cardiology Plus.

Ambient particulate matter has been associated consistently with an increased risk for mortality largely due to cardiovascular diseases.1 Although the relative risk estimates from epidemiological studies are small, they apply to almost the entire population of the United States. Consequently, exposure to ambient particles produces considerable burden of disease, and its mitigation offers the benefit of improving life expectancy.2 Articles see pp 941 and 949 Over the past decade, research has substantiated the understanding of the pathophysiological mechanisms linking ambient particles to the cardiovascular system3,4 once it was noted that ambient air pollution elicits systemic inflammatory responses in the general population.5 An update of the American Heart Association statement on air pollution and cardiovascular disease3 is under way. Mechanisms considered for active and secondhand smoke as well as ambient air pollution are strikingly similar.4,6,7 They include progression of atherosclerotic plaques to vulnerable forms, prothrombotic states, endothelial dysfunction, and altered autonomic nervous system control (Figure). Increased systemic oxidative stress is considered the key mechanism responsible for most of these pathophysiological changes. Increased risks for cardiovascular disease in general and coronary artery disease in particular have been documented for active and secondhand smoke as well as ambient particulate matter. Deep venous thrombosis has been added to this list recently.8 Figure. Overview on pathomechanism linking ambient air pollution,4 secondhand smoke,7 and active smoking to acute coronary syndromes. Nevertheless, the public health relevance of particulate matter in the light of the smoking literature remains hotly debated. Smokers are exposed to considerably higher cumulative doses of particulate matter than the general nonsmoking population. Mortality due to low doses of ambient particles may be considered counterintuitive compared with doses of particles tolerated by smoking individuals. A systematic assessment of the exposure-response function ranging from low doses of inhaled particles …

Age-dependent health risk from ambient air pollution: a modelling and data analysis of childhood mortality in middle-income and low-income countries

Background/Aim: Although health effects of air pollutants are reported in many countries around the world especially in western countries, few studies have been conducted in Thailand where pollution mix, weather conditions, and demographic characteristics are different. This study aims to investigate the short-term effects of ambient air pollution on hospital admissions for acute myocardial infarction (AMI) in Bangkok, Thailand. Methods: We obtained daily air pollution concentrations (O3, NO2, SO2, PM10, PM2.5, and CO) and weather variables monitored in Bangkok from 2006 to 2014. A total of 26,334 daily admissions for AMI were obtained from 72 hospitals in Bangkok during the study period. A time-series regression analysis with a generalized linear model was used to examine the effects of air pollution on hospital admissions by controlling for time trends and other possible confounders. The effect modifications by age (15-64 years and ≥ 65 years), gender, and season were also examined. Results: We found that an increase of 10 µg/m3 in O3, NO2, SO2, PM10, PM2.5 and 1 mg/m3 in CO at lag 01 day were associated with a 2.65% (95% CI: 0.94 to 4.39), 2.10% (0.95 to 3.26), 11.24% (4.25 to 18.70), 1.96% (0.95 to 2.98), 2.04% (0.58 to 3.52) and 10.80% (4.43 to 17.55) increase in hospital admissions for AMI, respectively. The effect estimate was attenuated after adjusting for co-pollutants. The effects of air pollutants were more evident in winter (November to February) than in summer (March to May) and monsoon (June to October) with higher effect for adults (15-64 years) compared to elderly (≥ 65 years). Males were more sensitive than females to the effect of air pollution, through the difference was not statistically significant. Conclusions: This study suggests that exposure to ambient air pollution poses significant risk on hospital admission for AMI, providing the data to reduce air pollution concentrations.

BackgroundAdverse respiratory effects of particulate air pollution have been identified by epidemiological studies. We aimed to examine the health effects of ambient particulate air pollution from wood burning on school-age students in Christchurch, New Zealand, and to explore the utility of urine and exhaled breath condensate biomarkers of exposure in this population.MethodsA panel study of 93 male students (26 with asthma) living in the boarding house of a metropolitan school was undertaken in the winter of 2004. Indoor and outdoor pollution data was continuously monitored. Longitudinal assessment of lung function (FEV1 and peak flow) and symptoms were undertaken, with event studies of high pollution on biomarkers of exposure (urinary 1-hydroxypyrene) and effect (exhaled breath condensate (EBC) pH and hydrogen peroxide concentration).ResultsPeak levels of air pollution were associated with small but statistically significant effects on lung function in the asthmatic students, but not healthy students. No significant effect of pollution could be seen either on airway inflammation and oxidative stress either in healthy students or students with asthma. Minor increases in respiratory symptoms were associated with high pollution exposure. Urinary 1-hydroxypyrene levels were raised in association with pollution events by comparison with low pollution control days.ConclusionThere is no significant effect of ambient wood-smoke particulate air pollution on lung function of healthy school-aged students, but a small effect on respiratory symptoms. Asthmatic students show small effects of peak pollution levels on lung function. Urinary 1-hydroxypyrene shows potential as a biomarker of exposure to wood smoke in this population; however measurement of EBC pH and hydrogen peroxide appears not to be useful for assessment of population health effects of air pollution.Some of the data presented in this paper has previously been published in Kingham and co-workers Atmospheric Environment, 2006 Jan; 40: 338–347 (details of pollution exposure), and Cavanagh and co-workers Sci Total Environ. 2007 Mar 1;374(1):51-9 (urine hydroxypyrene data).

The public health benefits of air pollution control

There are no reported studies on the effects of ambient air pollution on emergency department (ED) attendances in Sydney, Australia. This study aimed to determine associations between ambient air pollutants and ED attendances for cardiovascular disease (CVD) in those aged 65+ years. We constructed daily time series of hospital ED attendances, air pollutants and meteorological factors for the Sydney metropolitan area from 1 January 1997 to 31 December 2001. We used generalised linear models to determine associations between daily air pollution and daily ED attendances and controlled for the effects of long-term trends, seasonality, weather and other potential confounders. Increased ED attendances for all CVD, cardiac disease and ischaemic heart disease were seen with 24-h particulate pollution, 1-h NO(2), 8-h CO and 24-h SO(2). Air pollutants were associated with decreased ED attendances for stroke. The effects of air pollutants on CVD, cardiac disease and stroke attendances were generally greater in the cool period compared to the warm period. The single-pollutant effects of CO, O(3), NO(2) and SO(2) were essentially unchanged in two-pollutant models. Although air pollution levels in Sydney are relatively low compared to similar cities, we have demonstrated associations between ambient air pollutants and ED attendances for CVD in people aged 65+ years. Our study adds to the growing evidence for the effects of ambient air pollution on CVD outcomes even at relatively low ambient concentrations.

There is a growing body of literature on the adverse health effects of ambient air pollution. Children are more adversely affected by air pollution due to their biological susceptibility and exposure patterns. This review summarized the accumulated epidemiologic evidence with emphasis on studies conducted in Korea and heterogeneity in the literature. Based on systematic reviews and meta-analyses, there is consistent evidence on the association between exposure to ambient air pollution and children’s health, especially respiratory health and adverse birth outcomes, and growing evidence on neurodevelopmental outcomes. Despite these existing studies, the mechanism of the adverse health effects of air pollution and the critical window of susceptibility remain unclear. There is also a need to identify causes of heterogeneity between studies in terms of measurement of exposure/outcome, study design, and the differential characteristics of air pollutants and population.

Air pollution in Hanoi, Vietnam : evaluating effects on hospital admissions of children

Experimental data suggest that obesity enhances the effects of ambient air pollutants on exacerbation of asthma; however, there is little supporting epidemiological evidence. The aim of present study is to evaluate whether obesity modifies the association between ambient air pollution and respiratory symptoms and asthma in children. In Northeast China, 30 056 children aged 2-14 years were selected from 25 districts of seven cities. Parents of the children completed questionnaires that characterized the children's histories of respiratory symptoms and illness, and associated risk factors. Overweight and obesity were calculated with an age and sex-specific body mass index (BMI, kg m(-2)), with BMIs of greater than the 85th and 95th percentiles defining overweight and obesity, respectively. Average annual ambient exposure to particulate matter with an aerodynamic diameter 10 μm (PM(10)), sulfur dioxide (SO(2)), nitrogen dioxides (NO(2)) and ozone (O(3)) was estimated from data collected at monitoring stations in each of the 25 study districts. We observed consistent and significant interactions between exposure and obesity on respiratory symptoms and asthma. The associations between each pollutant's yearly concentrations and respiratory symptoms and asthma were consistently larger for overweight/obese children than for normal-weight children, with odds ratios (ORs) ranging from 1.17 per 31 μg m(-3) for PM(10) on wheeze (95% confidence interval (CI): 1.01, 1.36) to 1.50 per 10 μg m(-3) for NO(2) on phlegm (95% CI: 1.21, 1.87) and cough (95% CI: 1.24, 1.81). These results showed that overweight/obesity enhanced respiratory health effects of air pollution in the study children.

Urban Air Pollution: Why Is It a Health Problem?

Effects of ambient air pollution on daily hospital admissions for respiratory and cardiovascular diseases in Bangkok, Thailand