Children with asthma at risk of viral infection from flu or the common cold could also be at an increased risk of severe asthma attacks if they have been exposed to nitrogen dioxide pollution from sources such as vehicle exhausts or gas cookers.
A link between exposure to the air pollutant nitrogen dioxide and respiratory disease has been suggested. Viral infections are the major cause of asthma exacerbations. Anoop Chauhan from St Mary's Hospital, Portsmouth, UK, and colleagues assessed whether there is a relation between nitrogen dioxide exposure and the severity of asthma exacerbations caused by proven respiratory viral infections in children.
114 asthmatic children aged between 8 and 11 years (recruited from families where there were no smokers) recorded daily upper respiratory-tract symptoms (e.g., runny nose, sneezing, headache) and asthma symptoms (cough, wheeze,
shortness of breath), and measured personal nitrogen dioxide exposures every week for around a year.
The investigators confirmed all respiratory infections by laboratory analysis (using highly sensitive biotechnology to measure the viral genetic material) and compared childrens' exposure to nitrogen dioxide one week before the onset of infection with the severity of asthma attacks in the week after respiratory infection. They found that children with greater exposure to nitrogen dioxide were more likely to report more severe lower respiratory-tract symptoms which were in turn associated with exacerbated asthma symptoms the week after infection.
Anoop Chauhan comments: "We have shown that higher personal nitrogen dioxide exposure might increase the severity of virus-induced asthma exacerbations and these findings have potential implications for public health. Severe exacerbations have the largest effect on the health costs associated with asthma, especially those that result in visits to family doctors and hospital admissions. In asthmatic children with colds, high nitrogen dioxide pollution results in more severe exacerbations. These observations suggest that health costs associated with treating acute asthma exacerbations could be reduced through control of nitrogen dioxide pollution. Of equal concern is that these effects occurred at levels of nitrogen dioxide pollution considered to be safe under current international air-quality standards."
Contact: Dr Anoop J Chauhan, Portsmouth Hospitals NHS Trust, St Mary's Hospital, Milton Road, Portsmouth PO3 6AD UK; T) +44 (0) 23 9286 6360; F) +44 (0) 23 9286 6735; E) anoop.chauhan@porthosp.nhs.uk
From: THE LANCET.
Exposure to Pollution Before Viral Infection Linked to More Serious Asthma Attacks (p 1939)
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