The effects of outdoor air pollution on the respiratory health of Canadian children: A systematic review of epidemiological studies

You exhaust me! Air pollution exposure near schools during pick-up and drop-off times

Background

Public and healthcare practitioner awareness of climate change and the longitudinal health impacts of air pollution is growing; however, it is not always clear how to implement practical and feasible steps that individuals and communities can take to help decrease air pollution and protect children, and it can be challenging to request and enforce behaviour changes that the public associates with perceived personal inconvenience. In this context, it is important to consider common, chronic exposures that increase children's risks, especially when straightforward solutions with minimal negative impact where significant evidence-based positive results are available.

Aims

This article provides simple tips that healthcare providers, parents, and communities can use to advocate for decreased idling in school zones to improve air quality in and around schools.

Exposure to fine particulate matter and acute upper- and lower-respiratory tract infections (AURI and ALRI) in children under five years of age in India

As one of the world's polluted regions, we assessed the association between ambient PM_2.5 levels and acute lower and upper respiratory infection in India. We assessed 55,118 children from the 2015-2016 Demographic Health Survey in India using the information on levels of PM_2.5 in 2015 and 2016 from the Atmospheric Composition Analysis Group. We used the generalized estimating equation for the analysis reported as odds ratios and 95% confidence intervals for every 10 µg/m³ increase and quartiles in PM_2.5. Every 10 µg/m³ increase in levels of PM_2.5 associated with acute upper respiratory infection (OR 1.02, 95%CI: 1.02-1.03) and acute lower respiratory infection (OR 1.05, 95%CI: 1.03-1.06). This association was confirmed by quartile exposure assessments. Mitigation efforts must be continued implementing higher restrictions in India to ensure safe levels of air.

Effects of ambient air pollution on psychological stress and anxiety disorder: a systematic review and meta-analysis of epidemiological evidence

OBJECTIVES

Ambient air pollution (AAP) is an important risk factor for increased mental health morbidity. Studies have highlighted the effect of AAP on psychological stress and anxiety disorder. However, existing evidence regarding this is largely equivocal. This systematic review with meta-analysis aims to synthesize published evidence to calculate the pooled estimate of the effect of AAP on psychological stress and anxiety disorder.

CONTENT

A systematic bibliographic search was undertaken using PubMed, JGateplus, Google Scholar, and Cochrane Library for observational human studies published in English till 31st March 2020 reporting the effect of AAP on psychological stress and anxiety disorder. Study quality was assessed using the Joanna Briggs Institute critical appraisal tools. Meta-analysis was performed adopting a random-effects model using Meta-XL. Of 412 articles retrieved, a total of 30 articles [AAP and anxiety disorders, (n=17, 57%); AAP and psychological stress, (n=9, 30%) and AAP and both psychological stress and anxiety disorders, (n=4, 13%)] fulfilled the inclusion criteria covering a total population of 973,725 individuals. The pooled estimate (OR) of the effects of PM₁₀ on psychological stress was 1.03 [(95% CI: 1.00, 1.05) (p=0.17, I ²=41%)]. The pooled estimate of the effects of NO₂ and PM₁₀ on anxiety disorder was 0.93 [(95% CI: 0.89, 0.97) (p=0.91, I ²=0%)] and 0.88 [(95% CI: 0.78, 0.98) (p=0.01, I ²=59%)] respectively. The pooled estimate of the effects of PM_2.5 on anxiety Disorder was 0.88 [(95% CI: 0.72, 1.06) (p=0.00, I ²=80%)].

SUMMARY AND OUTLOOK

The present study provides the most updated pooled estimate of the effect of AAP on psychological stress and anxiety disorder. Future studies should focus on longitudinal studies conducted in LIC and LMIC countries using uniform and standardized criteria for exposure and outcome assessment as well as robust adjustment for confounders to minimize methodological heterogeneity resulting in reliable and comparable estimation of environmental mental health burden.

Residential Proximity to Biorefinery Sources of Air Pollution and Respiratory Diseases in New York State

Understanding potential health risks associated with biofuel production is critical to sustainably combating energy insecurity and climate change. However, the specific health impacts associated with biorefinery-related emissions are not yet well characterized. We evaluated the relationship between respiratory emergency department (ED) visits (2011-2015) and residential exposure to biorefineries by comparing 15 biorefinery sites to 15 control areas across New York (NY) State. We further examined these associations by biorefinery types (e.g., corn, wood, or soybean), seasons, and lower respiratory disease subtypes. We measured biorefinery exposure using residential proximity in a cross-sectional study and estimation of biorefinery emission via AERMOD-simulated modeling. After controlling for multiple confounders, we consistently found that respiratory ED visit rates among residents living within 10 km of biorefineries were significantly higher (rate ratios (RRs) range from 1.03 to 3.64) than those in control areas across our two types of exposure indices. This relationship held across biorefinery types (higher in corn and soybean biorefineries), seasons (higher in spring and winter), air pollutant types (highest for NO₂), and respiratory subtypes (highest for emphysema). Further research is needed to confirm our findings.

Inequalities and Inequities in Pediatric Respiratory Diseases

Social inequality refers to disparities in society that have the effect of limiting a group's socioeconomic, educational, and intellectual potential. Inequity in health means any limitation to access comprehensive health services that also hinders the achievement of well-being and favorable health outcomes. Strategies for more equitable growth to eradicate global poverty would contribute to reducing health inequities and improve health care outcomes. Coordinated efforts between governments, private sector, families, and interested stakeholders are needed. This article discusses inequality and inequity in pediatric respiratory diseases, the challenges confronted, and the strategies needed to mitigate these disparities.

Changes of air quality and its associated health and economic burden in 31 provincial capital cities in China during COVID-19 pandemic

With outbreak of the novel coronavirus disease (COVID-19), immediate prevention and control actions were imposed in China. Here, we conducted a timely investigation on the changes of air quality, associated health burden and economic loss during the COVID-19 pandemic (January 1 to May 2, 2020). We found an overall improvement of air quality by analyzing data from 31 provincial cities, due to varying degrees of NO2, PM2.5, PM10 and CO reductions outweighing the significant O3 increase. Such improvement corresponds to a total avoided premature mortality of 9410 (7273-11,144) in the 31 cities by comparing the health burdens between 2019 and 2020. NO2 reduction was the largest contributor (55%) to this health benefit, far exceeding PM2.5 (10.9%) and PM10 (23.9%). O3 instead was the only negative factor among six pollutants. The period with the largest daily avoided deaths was rather not the period with strict lockdown but that during February 25 to March 31, due to largest reduction of NO2 and smallest increase of O3. Southwest, Central and East China were regions with relatively high daily avoided deaths, while for some cities in Northeast China, the air pollution was even worse, therefore could cause more deaths than 2019. Correspondingly, the avoided health economic loss attributable to air quality improvement was 19.4 (15.0-23.0) billion. Its distribution was generally similar to results of health burden, except that due to regional differences in willingness to pay to reduce risks of premature deaths, East China became the region with largest daily avoided economic loss. Our results here quantitatively assess the effects of short-term control measures on changes of air quality as well as its associated health and economic burden, and such information is beneficial to future air pollution control.

Predicting Long-Term Respiratory Outcomes in Premature Infants: Is It Time to Move beyond Bronchopulmonary Dysplasia?

Premature birth has been shown to be associated with adverse respiratory health in children and adults; children diagnosed with bronchopulmonary dysplasia (BPD) in infancy are at particularly high risk. Since its first description by Northway et al. about half a century ago, the definition of BPD has gone through several iterations reflecting the changes in the patient population, advancements in knowledge of lung development and injury, and improvements in perinatal care practices. One of the key benchmarks for optimally defining BPD has been the ability to predict long-term respiratory and health outcomes. This definition is needed by multiple stakeholders for hosts of reasons including: providing parents with some expectations for the future, to guide clinicians for developing longer term follow-up practices, to assist policy makers to allocate resources, and to support researchers involved in developing preventive or therapeutic strategies and designing studies with meaningful outcome measures. Long-term respiratory outcomes in preterm infants with BPD have shown variable results reflecting not only limitations of the current definition of BPD, but also potentially the impact of other prenatal, postnatal and childhood factors on the respiratory health. In this manuscript, we present an overview of the long-term respiratory outcomes in infants with BPD and discuss the role of other modifiable or non-modifiable factors affecting respiratory health in preterm infants. We will also discuss the limitations of using BPD as a predictor of respiratory morbidities and some of the recent advances in delineating the causes and severity of respiratory insufficiency in infants diagnosed with BPD.

A mixed-methods community-based participatory research to explore stakeholder's perspectives and to quantify the effect of crop residue burning on air and human health in Central India: study protocol

Background

Crop residue burning adversely affects air quality and consequently human health. India, being one of the largest agro-economies of the world, produces around 500 Million tonnes of crop residue annually most of which is burnt on-farm. However, integrated studies that simultaneously quantify the effects of crop residue burning while exploring the subjective determinants of the practice are lacking in India. This paper describes the protocol for a longitudinal mixed methods research study employing a community-based participatory approach to fill this gap.

Methods

Both quantitative and qualitative data will be collected in a rural setting of the central Indian province of Madhya Pradesh, over 1 year. A steering committee comprising of the research team and community representatives will be formed. The proportion of cultivable land burnt in one crop burning season will be estimated. The association between crop residue burning, level of ambient air pollutants, and pulmonary function of village residents will be determined. Focus groups, interviews, and participatory rural appraisal methods will be used to explore stakeholder perspectives about crop residue burning. Potential barriers and opportunities for substituting burning with an alternative crop residue management technique will be ascertained as the basis for future interventions. Ethics approval has been obtained from the Institutional Ethics Committee of the National Institute for Research in Environmental Health (No: NIREH/BPL/IEC/2019–20/1494, dt 06/01/2020).

Discussion

This manuscript describes the protocol for a novel community-based participatory study to investigate thoroughly the phenomenon of crop residue burning from the perspective of the agricultural community through their active collaboration. The lack of comprehensive evidence regarding the factors responsible for crop residue burning in India underlines the importance of implementing this study protocol to fill in this critical gap in knowledge. While acknowledging that findings of this study will be not generalizable to agricultural communities other than the one studied, it is expected that the study will generate baseline evidence that might be beneficial in developing and implementing an appropriate intervention strategy.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12889-020-09844-6.

Review of the effect of air pollution exposure from industrial point sources on asthma-related effects in childhood

We reviewed epidemiologic studies of the association between exposure to air pollution from industries and asthma-related outcomes in childhood. We searched bibliographic databases and reference lists of relevant articles to identify studies examining the association between children's exposure to air pollution from industrial point-sources and asthma-related outcomes, including asthma, asthma-like symptoms, wheezing, and bronchiolitis. We extracted key characteristics of each study and when appropriate we performed a random-effects meta-analysis of results and quantified heterogeneity (I ²). Thirty-six studies were included in this review. Meta-analysis was generally not possible and limited to a few studies because of substantial variation across design characteristics and methodologies. In case-crossover studies using administrative health data, pooled odds ratio (OR) of hospitalization for asthma and bronchiolitis in children <5 years were 1.02 [95% confidence intervals (CI): 0.96, 1.08; I ² = 56%] and 1.01 (95% CI: 0.97, 1.05; I ² = 64%) per 10 ppb increase in the daily mean and hourly maximum concentration of sulfur dioxide (SO₂), respectively. For PM_2.5, pooled ORs were 1.02 (95% CI: 0.93, 1.10; I ² = 56%) and 1.01 (95% CI: 0.98, 1.03 I ² = 33%) per 10 μg/m³ increment in the daily mean and hourly maximum concentration. In cross-sectional studies using questionnaires, pooled ORs for the prevalence of asthma and wheezing in relation to residential proximity to industry were 1.98 (95% CI: 0.87, 3.09; I ² =71%) and 1.33 (95% CI: 0.86, 1.79; I ²= 65%), respectively. In conclusion, this review showed substantial heterogeneity across study designs and methods. Meta-analysis results suggested no evidence of an association for short-term asthma-related effects and an indication for long-term effects, but heterogeneity between results and limitations in terms of design and exposure assessment preclude drawing definite conclusions. Further well-conducted studies making use of a longitudinal design and of refined exposure assessment methods are needed to improve risk estimates.

Coal burning-derived SO2 and traffic-derived NO2 are associated with persistent cough and current wheezing symptoms among schoolchildren in Ulaanbaatar, Mongolia

Background

Children in Ulaanbaatar are exposed to air pollution, but few epidemiological studies have been conducted on the effects of environmental risk factors on children’s health. Also, no studies have yet examined the prevalence of respiratory symptoms in children in suburban areas, where air quality-monitoring stations have not yet been installed. This cross-sectional study evaluated the associations between outdoor air pollution and respiratory symptoms among schoolchildren in urban and suburban districts of Ulaanbaatar.

Methods

The ATS-DLD-78 C questionnaire was used to investigate the respiratory symptoms of schoolchildren aged 6–12 years (n = 1190) who lived in one of three urban districts or a suburban district of Ulaanbaatar. In each district, the outdoor concentrations of nitrogen dioxide (NO₂) and sulfur dioxide (SO₂) were measured at two sites (at ≤100 m and > 100 m from the nearest major road) in the 2-year period from 2015 to 2016. The associations between health outcomes and exposure to air pollutants were estimated using the multinomial logistic regression method.

Results

The outdoor concentration of SO₂ was significantly associated with persistent cough symptom (OR = 1.12, 95% CI 1.04–1.22). Furthermore, the outdoor concentration of NO₂ was significantly associated with the current wheezing symptom (OR = 1.33, 95% CI 1.01–1.75) among children in urban and suburban.

Conclusions

The prevalence of persistent cough symptom was markedly high among the schoolchildren in urban/suburban districts of Ulaanbaatar. Overall, the increases in the prevalence of respiratory symptoms among children might be associated with ambient air pollution in Ulaanbaatar.

SO2 Emission Estimates Using OMI SO2 Retrievals for 2005-2017

SO2 column densities from Ozone Monitoring Instrument provide important information on emission trends and missing sources, but there are discrepancies between different retrieval products. We employ three Ozone Monitoring Instrument SO2 retrieval products (National Aeronautics and Space Administration (NASA) standard (SP), NASA prototype, and BIRA) to study the magnitude and trend of SO2 emissions. SO2 column densities from these retrievals are most consistent when viewing angles and solar zenith angles are small, suggesting more robust emission estimates in summer and at low latitudes. We then apply a hybrid 4D-Var/mass balance emission inversion to derive monthly SO2 emissions from the NASA SP and BIRA products. Compared to HTAPv2 emissions in 2010, both posterior emission estimates are lower in United States, India, and Southeast China, but show different changes of emissions in North China Plain. The discrepancies between monthly NASA and BIRA posterior emissions in 2010 are less than or equal to 17% in China and 34% in India. SO2 emissions increase from 2005 to 2016 by 35% (NASA)-48% (BIRA) in India, but decrease in China by 23% (NASA)-33% (BIRA) since 2008. Compared to in situ measurements, the posterior GEOS-Chem surface SO2 concentrations have reduced NMB in China, the United States, and India but not in South Korea in 2010. BIRA posteriors have better consistency with the annual growth rate of surface SO2 measurement in China and spatial variability of SO2 concentration in China, South Korea, and India, whereas NASA SP posteriors have better seasonality. These evaluations demonstrate the capability to recover SO2 emissions using Ozone Monitoring Instrument observations.

Toward an Improved Air Pollution Warning System in Quebec

The nature of pollutants involved in smog episodes can vary significantly in various cities and contexts and will impact local populations differently due to actual exposure and pre-existing sensitivities for cardiovascular or respiratory diseases. While regulated standards and guidance remain important, it is relevant for cities to have local warning systems related to air pollution. The present paper proposes indicators and thresholds for an air pollution warning system in the metropolitan areas of Montreal and Quebec City (Canada). It takes into account past and current local health impacts to launch its public health warnings for short-term episodes. This warning system considers fine particulate matter (PM_2.5) as well as the combined oxidant capacity of ozone and nitrogen dioxide (O_x) as environmental exposures. The methodology used to determine indicators and thresholds consists in identifying extreme excess mortality episodes in the data and then choosing the indicators and thresholds to optimize the detection of these episodes. The thresholds found for the summer were 31 μg/m³ for PM_2.5 and 43 ppb for O_x in Montreal, and 32 μg/m³ and 23 ppb in Quebec City. In winter, thresholds found were 25 μg/m³ and 26 ppb in Montreal, and 33 μg/m³ and 21 ppb in Quebec City. These results are in line with different guidelines existing concerning air quality, but more adapted to the cities examined. In addition, a sensitivity analysis is conducted which suggests that O_x is more determinant than PM_2.5 in detecting excess mortality episodes.

Prevalence of childhood lead poisoning and respiratory disease associated with lead smelter emissions

BACKGROUND

The city of Port Pirie in South Australia has been a world leading centre for lead and zinc smelting and processing since 1889 that continues to cause contamination of its environment and resident population. This study quantifies the effect of lead and SO₂ emissions from Nyrstar Port Pirie Pty Ltd's smelter on blood lead and respiratory health outcomes, respectively, and establishes what air quality values are required to better protect human health.

METHOD

Blood lead and emergency department presentation data collected by South Australia Health (SA Health) and lead in air and SO₂ data collected by the South Australian Environment Protection Authority (SAEPA) were obtained and analysed to quantify health outcomes due to smelter emissions in Port Pirie. Regression analysis was used to assess the relationship between the concentration of lead in air and children's blood lead levels between the years of available data: 2003 to 2017. Ambient SO₂ concentrations (SAEPA) measured continuously between 2008 and 2018 were 24-hour averaged and compared to daily local emergency department respiratory presentation rates (available from July 2012 to October 2018). Rates of emergency department respiratory presentations at Port Pirie and regional comparators were calculated as age-standardised rates.

RESULTS

The data show that increases in ambient SO₂ concentrations are associated with increased rates of emergency department respiratory presentations of Port Pirie residents, in which children are over-represented. The 30-day rolling average of respiratory presentations was significantly associated (p < 0.05) with incremental increases in SO₂. Analysis of the relationship between lead in air and blood lead shows that annual geometric mean air lead concentrations need to be <0.11 μg/m³ to ensure the geometric mean blood lead of Port Pirie children under 5 years is ≤5 μg/dL. For children aged 24 months, lead in air needs to be no greater than 0.082 μg/m³ (annual geometric mean) to ensure geometric mean blood lead does not exceed 5 μg/dL.

CONCLUSION

Current smelting emissions continue to pose a clear risk of harm to Port Pirie children. Allowable emissions must be lowered significantly to limit adverse childhood health outcomes including respiratory illness and IQ, academic achievement and socio-behavioural problems that are associated with lead exposure at levels experienced by Port Pirie children. Current SO₂ levels are likely to be responsible for increased rates of emergency department respiratory presentations in Port Pirie compared with other South Australian locations. As a minimum, Australian SO₂ air quality standards need to be enforced in Port Pirie to better protect human health. Lead in air needs to be approximately 80% lower than the current national standard (0.5 μg/m³) to ensure that the geometric blood lead of children under 5 years is less than or equal to 5 μg/dL.

Acute effects of ambient air pollution on outpatient children with respiratory diseases in Shijiazhuang, China

Background

Associations between ambient air pollution and child health outcomes have been well documented in developed countries such as the United States; however, only a limited number of studies have been conducted in developing countries. This study aimed to explore the acute effects of five ambient air pollutants (inhalable particles [PM₁₀], fine particles [PM_2.5], sulfur dioxide [SO₂], nitrogen dioxide [NO₂] and 0zone [O₃]) on children hospital outpatients with respiratory diseases in Shijiazhuang, China.

Methods

Three years (2013–2015) of daily data, including cause-specific respiratory outpatient records and the concentrations of five air pollutants, were collected to examine the short-term association between air pollution and children’s respiratory diseases; using a quasi-Poisson regression generalized additive model. Stratified analyses by season and age were also performed.

Results

From 2013 to 2015, a total of 551,678 hospital outpatient records for children with respiratory diseases were collected in Shijiazhuang, China. A 10 μg/m³ increase in a two-day average concentration (lag01) of NO₂, PM_2.5, and SO₂ corresponded to an increase of 0.66% (95% confidence interval [CI]: 0.30–1.03%), 0.13% (95% CI: 0.02–0.24%), and 0.33% (95% CI: 0.10–0.56%) in daily hospital outpatient visits for children with respiratory diseases, respectively. The effects were stronger in the transition season (April, May, September and October) than in other seasons (the hot season [June to August] and the cool season [November to March]). Furthermore, results indicated a generally stronger association in older (7–14 years of age) than younger children (< 7 years of age).

Conclusions

This research found a significant association between ambient NO₂, PM_2.5, and SO₂ levels and hospital outpatient visits in child with respiratory diseases in Shijiazhuang, China.

Proximity to two main sources of industrial outdoor air pollution and emergency department visits for childhood asthma in Edmonton, Canada

OBJECTIVE

Children are recognized to be more susceptible than healthy adults to the effects of air pollution; however, relatively few Canadian studies of children have focused on industrial emissions. We conducted a spatial cross-sectional study to explore associations between emergency department (ED) visits for childhood asthma and residential proximity to two industrial sources of air pollution (coal-fired power plant and petrochemical industry) in Edmonton, Canada.

METHODS

Using administrative health care data for Alberta between 2004 and 2010, we conducted a spatial analysis of disease clusters of count data around these two industrial sources. The distance from children's place of residence to these industrial sources was determined by using the six-character postal code from the children's ED visit. Clusters of cases were identified at the census dissemination area. Negative binomial multivariable spatial regression was used to estimate the risks of clusters in relation to the distance to these industrial sources.

RESULTS

The relative risk of ED visits for asthma, calculated using a spatial scan test for events, was 10.4 (p value &lt;0.01) within the power plant area when compared with the outside area. In addition, there was an inverse association of the distance to the power plant (coefficient = -0.01 per km) with asthma visits when multivariable models were used. No asthma clusters were identified around the petrochemical industrial area.

CONCLUSION

Our analyses revealed that there was a cluster of ED visits for asthma among children who lived near the coal-fired power plant just outside Edmonton.

Ambient air pollution and the risk of pregnancy loss: a prospective cohort study

OBJECTIVE

To estimate the association of pregnancy loss with common air pollutant exposure. Ambient air pollution exposure has been linked to adverse pregnancy outcomes, but few studies have investigated its relationship with pregnancy loss.

DESIGN

Prospective cohort study.

SETTING

Not applicable.

PATIENT(S)

A total of 343 singleton pregnancies in a multisite prospective cohort study with detailed protocols for ovulation and pregnancy testing.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Timing of incident pregnancy loss (from ovulation).

RESULT(S)

The incidence of pregnancy loss was 28% (n = 98). Pollutant levels at women's residences were estimated using modified Community Multiscale Air Quality models and averaged during the past 2 weeks (acute) and the whole pregnancy (chronic). Adjusted Cox proportional hazards models showed that an interquartile range increase in average whole pregnancy ozone (hazard ratio [HR] 1.12, 95% confidence interval [CI] 1.07-1.17) and particulate matter <2.5 μm (HR 1.13, 95% CI 1.03-1.24) concentrations were associated with faster time to pregnancy loss. Sulfate compounds also appeared to increase risk (HR 1.58, 95% CI 1.07-2.34). Last 2 weeks of exposures were not associated with loss.

CONCLUSION(S)

In a prospective cohort of couples trying to conceive, we found evidence that exposure to air pollution throughout pregnancy was associated with loss, but delineating specific periods of heightened vulnerability await larger preconception cohort studies with daily measured air quality.

A review of AirQ Models and their applications for forecasting the air pollution health outcomes

Even though clean air is considered as a basic requirement for the maintenance of human health, air pollution continues to pose a significant health threat in developed and developing countries alike. Monitoring and modeling of classic and emerging pollutants is vital to our knowledge of health outcomes in exposed subjects and to our ability to predict them. The ability to anticipate and manage changes in atmospheric pollutant concentrations relies on an accurate representation of the chemical state of the atmosphere. The task of providing the best possible analysis of air pollution thus requires efficient computational tools enabling efficient integration of observational data into models. A number of air quality models have been developed and play an important role in air quality management. Even though a large number of air quality models have been discussed or applied, their heterogeneity makes it difficult to select one approach above the others. This paper provides a brief review on air quality models with respect to several aspects such as prediction of health effects.

Seven-day cumulative effects of air pollutants increase respiratory ER visits up to threefold

OBJECTIVE

Children are especially vulnerable to respiratory injury induced by exposure to air pollutants. In the present study, we investigate periods of up to 7 days, and evaluate the lagged effects of exposure to air pollutants on the daily number of children and adolescents visiting the emergency room (ER) for the treatment of lower respiratory obstructive diseases (LROD), in the city of São Paulo, Brazil.

METHODS

Daily records of LROD-related ER visits by children and adolescents under the age of 19, from January 2000 to December 2007 (2,922 days) were included in the study. Time-series regression models (generalized linear Poisson) were used to control for short- and long-term trends, as well as for temperature and relative humidity. Third-degree polynomial lag models were used to estimate both lag structures and the cumulative effects of air pollutants. Effects of air pollutants were expressed as the percentage increase in LROD-related ER visits.

RESULTS

We observed an acute effect at the same day of exposure to air pollutants; however, the cumulative effects of air pollutants on the number of LROD-related ER visits was almost threefold greater than the one observed at the same day of exposure to PM₁₀ , SO₂ , and NO₂ mainly in children aged 5 years and under. The 7-day cumulative effect of SO₂ reached 11.0% (95% CI: 5.0-16.7) increase in visits. Conclusion and Relevance: This study highlights the effects of intermediate-term exposure to air pollutants on LROD in children. Pediatr Pulmonol. 2017;52:205-212. © 2016 Wiley Periodicals, Inc.

Before the first breath: prenatal exposures to air pollution and lung development

Various environmental contaminants are known to impair the growth trajectories of major organs, indirectly (gestational exposure) or directly (postnatal exposure). Evidence associates pre-gestational and gestational exposure to air pollutants with adverse birth outcomes (e.g., low birth weight, prematurity) and with a wide range of diseases in childhood and later in life. In this review, we explore the way that pre-gestational and gestational exposure to air pollution affects lung development. We present results in topics underlining epidemiological and toxicological evidence. We also provide a summary of the biological mechanisms by which air pollution exposure possibly leads to adverse respiratory outcomes. We conclude that gestational and early life exposure to air pollutants are linked to alterations in lung development and function and to other negative respiratory conditions in childhood (wheezing, asthma) that may last into adulthood. Plausible mechanisms encompass changes in maternal physiology (e.g., hypoxia, oxidative stress and inflammation) and DNA alterations in the fetus. Evidence for pre-gestational and gestational effects on the lung is scarce compared with that on early life exposure and further studies are needed. However, the suggested mechanisms are credible and the evidence of pre-gestational and gestational air pollution exposure is robust for adverse birth outcomes. Air pollutants might change lung developmental trajectories of the unborn child predisposing it to diseases later in life highlighting the urgent need for controls on urban air pollution levels worldwide.