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08-12-2009 | Respiratory | Article

Air pollution affects SABA efficacy in asthmatic children

Abstract

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MedWire News: Increases in daily air pollution levels are associated with reductions in bronchodilation response to short-acting β-agonists (SABAs) in children with asthma, researchers have found.

Writing in the journal Chest, Fernando Holguin (University of Pittsburgh, Pennsylvania, USA) and team explain: “Increased outdoor air pollution levels are associated with more frequent use of rescue inhalers in subjects with asthma.

“However, it is unknown whether this phenomenon is explained by an air pollution-mediated increase in respiratory symptom severity or whether air pollutants decrease the efficacy of SABAs.”

To investigate, the researchers studied 85 children with mild-to-moderate asthma, aged between 7 and 12 years, who were living in Mexico City.

Fluctuations in outdoor levels of nitrogen dioxide (NO2), ozone (O3), and fine particulate matter (PM2.5) near the children’s homes were compared with percentage changes in their FEV1 after treatment with SABAs.

Analysis revealed that a same-day interquartile increase of 10 ppb in NO2 concentration was associated with an average 15% reduction in FEV1 response to SABA therapy. This finding remained significant after accounting for NO2 levels during the preceding 3 days.

The researchers also found that an interquartile increase of 16 ppb in O3 concentration was associated with an 11% reduction in FEV1 response to SABA therapy 5 days later. However, FEV1 response to SABA therapy was not significantly affected by shorter lag times in O3 concentration increases.

The team found no significant reductions in response to SABA therapy associated with same-day or lag-time increases in PM2.5. Also, there were no significant reductions in FEV1 response to SABAs among children who were taking inhaled corticosteroids.

Holguin and team conclude: “Our results suggest that outdoor air pollution is associated with reduced bronchodilator response in children with asthma. This phenomenon may be secondary to air pollution-mediated increase in airway inflammation.

“Therefore, our results suggest that increases in outdoor air pollution may impair the efficacy of SABAs and may therefore adversely influence asthma control.”

MedWire (www.medwire-news.md) is an independent clinical news service provided by Current Medicine Group, a trading division of Springer Healthcare Limited. © Springer Healthcare Ltd; 2009

By Mark Cowen

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