ASTHMA onset is significantly more likely after long-term exposure to road traffic and outdoor air pollution according to a new study, which should add to calls for greater efforts to be made to limit air pollution emissions in cities. The researchers also provided fresh insights into the mechanisms that cause this link, examining the concentration of 8-isoprostane (8-iso), which is thought to be a biomarker of tissue damage in the lungs.
The team examined French cohort data from 608 adults, 240 of whom had asthma symptoms, asthma attacks, or had used asthma medications over the last 12 months, to estimate the impact of exposure to ozone and particulate matter air pollutants and high-intensity traffic. Additionally, associations between long-term exposure to outdoor air pollution, exhaled 8-iso, and current asthma status were analysed, with the concentration of 8-iso measured using a non-invasive test on the exhaled breath of participants.
After controlling for other factors that can affect asthma including smoking and age, the team found that the risk of current asthma increased due to high traffic intensity, ozone exposure, and 8-iso concentration. In those participants without asthma, exposure to particulate matter was found to significantly increase exhaled 8-iso concentration.
“For the first time in adults, we found associations between long-term exposures to outdoor air pollution, exhaled 8-iso concentration, and current asthma,” explained lead researcher Anaïs Havet, Inserm, Paris, France. “Based on this, we think that 8-iso is a marker related to one of the underlying biological mechanisms by which outdoor air pollution increases the risk of experiencing asthma symptoms, asthma attacks, or the need for use of asthma medications.”
Reducing Pollution Levels
The team believe the findings show that much greater efforts need to be made to reduce pollution in cities around the world, with an emphasis on fewer cars and more efficient public transport.
They stated that larger longitudinal studies are now needed to confirm these results, with the study focussing only on air pollution at the home address of the participants and not at other locations.
James Coker, Reporter