Uncontrolled asthma linked to air pollution exposure

http://www.medicalnewstoday.com/articles/229016.php

Article Date: 20 Jun 2011 - 16:00 PDT

People with asthma exposed to higher levels of ozone and particulate matter are much more likely to have poorer asthma control, researchers reported in the Journal of Epidemiology and Community Health. Long-term ozone exposure raises an asthma patient's likelihood to have uncontrolled asthma by 69%, while long-term exposure to particulate matter raises the risk by 35%, the authors added.

Even after taking into account known risk factors linked to poorly controlled asthma, such as obesity, inhaled corticosteroid use, and smoking, the findings still held true.

The researchers explained that prior studies had established a link between air pollution and worsening respiratory symptoms, more hospitalizations and increased use of prescription drugs. However, none had examined what the impact of long-term air pollution might be on asthma control.

The investigators gathered data from the follow-up to the Epidemiological study on the Genetics and Environment of Asthma (EGEA), involving 501 adult participants in five French cities, all with active asthma. They had filled in a questionnaire on respiratory health between 2003 and 2007.

Using data from the Institut Francais de l'Environnement (French Institute of the Environment), they calculated levels of O3 (ozone), NO2 (nitrous oxide) and PM10 (particulate matter) that each participant had been exposed to where they lived.

They measured asthma control according to data gathered on symptoms, asthma attacks, and lung function or FEV1 (forced expiratory volume in 1 second).

Data on pollutant levels were available for 481 patients. 44% of them had well-controlled asthma, 29% had partially controlled asthma, but 27% had poorly controlled asthma.

Calculated average levels of pollutants during the study period were:
Nitrous oxide - were 32 ug/m3
Ozone - 46 ug/m3
Particulate matter - 21 ug/m3
Both ozone and particulate matter levels were strongly linked to poorer asthma control. Long-term ozone exposure increased poor asthma control risk by 69%, and by 35% for particulate matter long-term exposure.

Females and older individuals of both sexes were more likely to experience poorly controlled asthma.

The authors concluded:

"Our results indicate that both ambient O3 and PM10 concentrations jeopardise asthma control in adults. The results are robust."

Source: Journal of Epidemiology and Community Health