Review: Indoor Nitrogen Dioxide and VOC Exposures: Summary of Evidence for an Association with Childhood Asthma and a Case for the Inclusion of Indoor Ultrafine Particle Measures in Future Studies

Abstract

Childhood asthma is a complex disease having both genetic and environmental risk factors. As such, it is important to identify indoor exposures that may contribute to asthma symptoms in order to minimise the likelihood of disease onset or exacerbation. Here we summarise epidemiological evidence regarding the potential relationship between indoor nitrogen dioxide, volatile organic compounds (VOCs) and childhood asthma. In general, VOC exposure studies have been more consistent in demonstrating a significant relationship with asthma or related symptoms, and studies of indoor nitrogen dioxide exposure are limited in that most do not control for indoor VOC exposures. Therefore, when possible, future studies should include both types of exposure measures as well as those for other potential risk factors such as ultrafine particles that have been shown to contribute to airway inflammation.