Abstract
There is growing evidence that asthma symptoms can be aggravated or events triggered by exposure to indoor nitrogen dioxide (NO2) emitted from unflued gas heating.
The impact of NO2 on the respiratory health of children with asthma was explored as a secondary analysis of a randomised community trial, involving 409 households during the winter period in 2006 (June to September).
Geometric mean indoor NO2 levels were 11.4 μg·m−3, while outdoor NO2 levels were 7.4 μg·m−3. Higher indoor NO2 levels (per logged unit increase) were associated with greater daily reports of lower (mean ratio 14, 95% CI 1.12–1.16) and upper respiratory tract symptoms (mean ratio 1.03, 95% CI 1.00–1.05), more frequent cough and wheeze, and more frequent reliever use during the day, but had no effect on preventer use. Higher indoor NO2 levels (per logged unit increase) were associated with a decrease in morning (-17.25 mL, 95% CI -27.63– -6.68) and evening (-13.21, 95% CI -26.03– -0.38) forced expiratory volume in 1 s readings. Outdoor NO2 was not associated with respiratory tract symptoms, asthma symptoms, medication use or lung function measurements.
These findings indicate that reducing NO2 exposure indoors is important in improving the respiratory health of children with asthma.
Footnotes
Support Statement
The Housing, Heating and Health Study Team greatly appreciates the funding support from: the Health Research Council of New Zealand; Contact Energy; Ministry for the Environment; Housing New Zealand Corporation; Hutt Valley District Health Board; Capital and Coast District Health Board; and the LPG Association. A full list of public sponsors is available at www.wnmeds.ac.nz/healthyhousing.html
Clinical Trial
This study is registered at ClinicalTrials.gov with the identifier NCT00489762.
Statement of Interest
A statement of interest for P. Howden-Chapman can be found at www.erj.ersjournals.com/site/misc/statements.xhtml
- Received July 21, 2009.
- Accepted November 10, 2010.
- ©ERS 2011
