Air pollution from industries and asthma onset in childhood: A population-based birth cohort study using dispersion modeling

https://doi.org/10.1016/j.envres.2020.109180Get rights and content

Highlights

  • We studied childhood asthma onset and residential exposure to industrial emissions.

  • We used a population-based birth cohort in Quebec, Canada, 2002–2011.

  • Residential exposure to industrial emissions was estimated from dispersion modeling.

  • Ambient PM2.5, NO2 and SO2 from industries was associated with asthma onset.

  • Associations were independent from those of regional PM2.5 and traffic-related NO2.

Abstract

Background

Despite evidence that ambient air pollution may play a role in the development of asthma, little is known about the potential contribution of industrial emissions.

Objective

We used a population-based birth cohort to investigate the association between asthma onset in childhood and residential exposure to industrial emissions, estimated from atmospheric dispersion modeling.

Methods

The study population comprised all children born in the province of Quebec, Canada, 2002-2011. Asthma onset were ascertained from health administrative databases with validated algorithms. We used atmospheric dispersion modeling to develop time-varying annual mean concentration of ambient PM2.5, NO2 and SO2 at participants' residence from industries. For each pollutant, we assessed the association between industrial emissions exposure and childhood asthma onset using Cox proportional hazard model, adjusted for sex, material and social deprivation and calendar year. Sensitivity analysis included adjusting for long-term regional and traffic-related ambient PM2.5 and NO2, and assessing potential confounding by unmeasured secondhand smoke.

Results

The cohort included 722,667 children and 66,559 incident cases of asthma. For all pollutants, we found a non-linear association between childhood asthma onset and residential ambient air pollutant concentration from industries, with stronger effects at lower concentrations. A change from 25th to the 75th percentile in the mean annual ambient concentration of PM2.5 (0.13 μg/m3), NO2 (1.0 μg/m3) and SO2 (1.6 μg/m3) from industrial emissions was associated with a 19% (95% CI: 17-20%), 21% (95% CI: 19-23%) and 23% (95% CI: 21-24%) increase in the risk of asthma onset in children, respectively. For PM2.5 and NO2, associations were persisting after adjustments for long-term regional PM2.5 and traffic-related NO2 ambient concentration.

Conclusion: Residential exposure to industrial emissions estimated from dispersion modeling was associated with asthma onset in childhood. Importantly, associations were stronger at lower concentrations and independent from those of other sources, thus adding up to the burden of regional and traffic-related air pollution.

Introduction

Respiratory diseases represent a significant burden on both the health of the population as well as the healthcare system (GBD, 2017). Asthma is the most prevalent chronic respiratory disease; according to the World Health Organization (WHO), 235 million people worldwide, of all ethnic groups and ages are suffering from asthma (GBD, 2017; WHO, 2019a). It is also the most common chronic disease in children (WHO, 2019b; Global Initiative for Asthma (GINA), 2017). The etiology of asthma is complex, and a number of risk factors have been identified, including exposure to air pollution (Beasley et al., 2015; Gershon et al., 2010; Subbarao et al., 2009a; Subbarao et al., 2009b). Over the past decade several studies have investigated the association between outdoor air pollution and asthma onset, and the conclusions of most recent review and meta-analysis of 41 studies, including 21 birth cohort studies, support the hypothesis that childhood exposure to air pollution plays a causal role in the development of the disease (Khreis et al., 2017). These evidences mostly derived from studies conducted in urban settings, thus focusing on urban and traffic-related air pollutants, including nitrogen dioxide (NO2) and particulate matter of aerodynamic diameters ≤ 2.5 μm (PM2.5).

Industries may be significant contributors to air pollution experienced by local populations. Very few cohort studies (Clark et al., 2010; Buteau et al., 2018) have investigated the possible contribution of industrial emissions to the development of asthma. Clark et al. (2010) found that incidence of asthma diagnosis in children aged up to 3–4 years was associated with the inverse-distance weighted summation of emissions from industrial emitters within a 10 km radius of the residence at birth and during the first year of life. In the other cohort study (Buteau et al., 2018), we found that asthma onset in children was associated with some indicators of exposure to industries developed from the distance between the residence of cohort subjects and the point sources, the tons of air pollutant (PM2.5 and sulphur dioxide (SO2)) emitted by industries, and the percent of time that participants' residence were downwind of industries. Specifically findings indicated that children living in proximity to industries were at greater risk of asthma onset than those who were not, and, that among children exposed the magnitude of the risk of developing the disease increased with the exposure. However, these two cohort studies (Clark et al., 2010; Buteau et al., 2018) were mainly limited by the exposure assessment, which relied on some indicators of exposure. Land-use and terrain as well as meteorology are among factors that contribute to local population's exposure to industrial pollutants.

We sought to consolidate findings from our previous study (Buteau et al., 2018) associating asthma onset in children and to some indicators of exposure to industrial emissions, by refining the exposure assessment. Specifically, we developed estimates of exposure to industrial emissions at residential location from atmospheric dispersion modeling and we assessed the association with childhood asthma onset using the Quebec population-based birth cohort.

Section snippets

Study population

Detail of the study design has been presented in a previous publication (Buteau et al., 2018). Briefly, we used a population-based birth cohort constructed from the Quebec Integrated Chronic Disease Surveillance System (QICDSS) (Blais et al., 2014). The QICDSS is developed from the linkage of health administrative datasets that include, among others, the registration file from the Quebec medicare system (Régie de l'assurance maladie du Québec, RAMQ), the hospital discharge file, and the fee-for

Results

Table 1 describes the birth cohort that comprised 722,667 children born in Quebec between April 1, 2002, and March 31, 2011. On average, children were followed for 4.4 years, for a total of 3.17 million person-years of observations. Throughout the study period we identified 66,591 incident cases of asthma, most of them occurring before four years of age (Fig. 1).

Table 2 shows the distribution of annual average concentrations of industrial emission-related air pollutants estimated by CALPUFF

Discussion

In this population-based birth cohort study, we assessed the associations between residential exposure to industrial emission-related ambient air pollutants and new-onset of childhood asthma. Our findings for exposure to industrial PM2.5, NO2 and SO2 were consistent; associations were all positive and non-linear, with concentration-response curve indicating stronger effects at lower concentrations and no discernible threshold. The relatively large increase in risk, despite very low change in

Conclusions

In this population-based birth cohort, new-onset of asthma in childhood was significantly associated with exposure at residential location to ambient air pollutant concentration emitted from industrial point-sources, estimated by dispersion modeling. Importantly, the concentration-response curves showed no evidence of a threshold and stronger effects at lower concentrations, suggesting that even low industrial air emissions may contribute to the development of asthma in childhood. Furthermore,

Declaration of competing interest

None declared.

Acknowledgements

The project was carried out in the context of the Quebec ministerial health surveillance plan. The use of the Quebec Integrated Chronic Disease Surveillance System (QICDSS) has been approved by the government for agencies managing databases, the Research Ethics Board of public health and the Commission d'accès à l'information (CAI). This work was funded by the Canadian Institutes of Health Research (CIHR) (grant # 246200) and by Health Canada's Clean Air Regulatory Agenda. Some analyses were

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