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Published on: August 7, 2017
Influence of ambient air pollutant sources on clinical encounters for infant bronchiolitis
Catherine J Karr1, Paul A Demers, Mieke W Koehoorn
1Department of Pediatrics, University of Washington, 401 Broadway, Box 359739, Seattle, WA 98104, USA. ckarr@u.washington.edu
Insights
Exposure to air pollutants like nitrogen dioxide and wood smoke is linked to increased infant bronchiolitis risk. Traffic and industrial emissions may also contribute to this respiratory illness in infants.
Area of Science:
- Environmental Health
- Pediatrics
- Epidemiology
Background:
- Limited data exists on the impact of ambient air pollution on infant bronchiolitis.
- Infant bronchiolitis is a common respiratory infection requiring clinical attention.
Purpose of the Study:
- To investigate the association between various air pollutants and their sources with infant bronchiolitis.
- To quantify the risk of infant bronchiolitis related to specific environmental exposures.
Main Methods:
- A case-control study involving 11,675 infants diagnosed with bronchiolitis in British Columbia.
- Exposure assessment included particulate matter (PM2.5, PM10), nitrogen oxides (NO2/NO), sulfur dioxide (SO2), carbon monoxide (CO), ozone (O3), traffic proximity, wood smoke, and industrial emissions.
- Conditional logistic regression was used to estimate risks, adjusting for various individual and maternal factors.
Main Results:
- Increased risk of infant bronchiolitis was associated with higher exposure to NO2, SO2, CO, wood smoke, and industrial emissions.
- Living within 50 meters of a major highway showed a 6% increased risk.
- No adverse effect was observed for PM10, PM2.5, or black carbon; ozone exposure showed a negative correlation with bronchiolitis risk.
Conclusions:
- Air pollutants from traffic, local industrial sources, and wood smoke are potential contributors to infant bronchiolitis.
- These findings highlight the need for strategies to reduce air pollution exposure to protect infants from respiratory illnesses.
Rationale:
Data regarding the influence of ambient air pollution on infant bronchiolitis are few.
Objectives:
We evaluated the impact of several air pollutants and their sources on infant bronchiolitis.
Methods:
Infants in the Georgia Air Basin of British Columbia with an inpatient or outpatient clinical encounter for bronchiolitis (n = 11,675) were matched on day of birth to as many as 10 control subjects. Exposure to particulate matter with a diameter of 2.5 mum or less (PM(2.5)), PM(10), NO(2)/NO, SO(2), CO, and O(3) were assessed on the basis of a regional monitoring network. Traffic exposure was assessed using regionally developed land use regression (LUR) models of NO(2), NO, PM(2.5), and black carbon as well as proximity to highways. Exposure to wood smoke and industrial emissions was also evaluated. Risk estimates were derived using conditional logistic regression and adjusted for infant sex and First Nations (Canadian government term for recognized aboriginal groups) status and for maternal education, age, income-level, parity, smoking during pregnancy, and initiation of breastfeeding.
Measurements And Main Results:
An interquartile increase in lifetime exposure to NO(2), NO, SO(2), CO, wood-smoke exposure days, and point source emissions score was associated with increased risk of bronchiolitis (e.g., adjusted odds ratio [OR(adj)] NO(2), 95% confidence interval [CI], 1.12, 1.09-1.16; OR(adj) wood smoke, 95% CI, 1.08, 1.04-1.11). Infants who lived within 50 meters of a major highway had a 6% higher risk (1.06, 0.97-1.17). No adverse effect of increased exposure to PM(10), PM(2.5), or black carbon, was observed. Ozone exposure was negatively correlated with the other pollutants and negatively associated with the risk of bronchiolitis.
Conclusions:
Air pollutants from several sources may increase infant bronchiolitis requiring clinical care. Traffic, local point source emissions, and wood smoke may contribute to this disease.
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