Asthma

Air pollution triggers childhood asthma exacerbations


The risk of childhood asthma exacerbations is increased within hours of exposure to high levels of air pollution, a study of Queensland hospital ED presentations has shown.

Rates of emergency department visits for asthma in children were significantly increased immediately after exposure to air pollutants such as and nitrogen dioxide (NO2) and ozone (O3), an analysis of hospital data for 2013–2015 in Brisbane found.

Researchers investigated possible links between air pollution levels and 3121 ED visits for asthma in children aged 0–14 years, by examining hour-by-hour associations between pollutant exposure levels and ED visits.

After adjusting for factors such as humidity, temperature and circulating respiratory virus levels they found that that the risk of ED visits for asthma increased significantly within four hours after exposure to NO2 (Odds Ratio 1.36) and one hour of exposure to ozone (OR 1.17).

The link between NO2 and asthma exacerbations was stronger in school-age children (age 5-14), with the increased risk ranging between 1.38 to 3.61, than that in preschool-age children (age 0-4).

This might be because NO2 is a major traffic air pollutant, and school-age children could be more likely to be exposed to it on the way to school, the researchers suggested.

There was no overall correlation between exposure to air pollution particles with diameter ≤10 μm (PM10), or particle with diameter ≤2.5 μm (PM2.5),

However, pre-school age children appeared to be more vulnerable to asthma ED visits with higher levels of PM10, with the risk ranging up to 1.88 compared to school age children.

Other trends revealed by the analysis were that in general, boys were more vulnerable than girls to ozone-related asthma ED visits (OR: 1.24 vs 1.06), and that the association of risk of ED visits for asthma was seen with air pollution exposure in daytime, but not at night-time.

The study authors said the findings supported the hypothesis that risk of childhood asthma exacerbations increases within a few hours of air pollution exposure.

“Minimising daytime exposure to air pollution may reduce the risk of childhood asthma exacerbations,” they concluded.

The findings are published in Environmental Research.

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