Air pollution increases chronic lung disease risk

Air pollution has come up as a major concern in the modern world considering its long-lasting and serious effects on human lungs.

Exposure to outdoor air pollution is linked to decreased lung function and an increased risk of developing chronic obstructive pulmonary disease (COPD), recent findings suggest.

COPD is a long-term condition linked to reduced lung function that causes inflammation in the lungs and a narrowing of the airways, making breathing difficult.

According to the Global Burden of Disease (GBD) project, COPD is the third leading cause of death worldwide, and the number of global COPD deaths is expected to increase over the next ten years.

Lung function normally declines as we age, but the new research, published in the European Respiratory Journal, suggests that air pollution may contribute to the ageing process and adds to the evidence that breathing in polluted air harms the lungs.

"There are surprisingly few studies that look at how air pollution affects lung health. To try and address this, we assessed more than 300,000 people using data from the UK Biobank study to examine whether air pollution exposure was linked to changes in lung function and whether it affected participants' risk of developing COPD," explained Anna Hansell, Environmental Epidemiology in the Centre for Environmental Health and Sustainability at the University of Leicester.

As part of the study, the researchers used a validated air pollution model to estimate the levels of pollution that people were exposed to at their homes when they enrolled in the UK Biobank study.

The types of pollutants the researchers investigated included particulate matter (PM10), fine particulate matter (PM2.5) and nitrogen dioxide (NO2), which are produced by burning fossil fuels from the car and other vehicle exhausts, power plants and industrial emissions.

Participants answered detailed health questionnaires as part of the UK Biobank data collection, and lung function was measured using spirometry tests performed by medical professionals at Biobank assessment centres at enrolment between 2006 and 2010.

Spirometry is a simple test used to help diagnose and monitor certain lung conditions by measuring how much air can be breathed out in one forced breath.

The data showed that for each annual average increase of five micrograms per cubic meter of PM2.5 in the air that participants were exposed to at home, the associated reduction in lung function was similar to the effects of two years of ageing.

When the researchers assessed COPD prevalence, they found that among participants living in areas with PM2.5 concentrations above World Health Organization (WHO) annual average guidelines of ten micrograms per cubic meter (10 mg/m3), COPD prevalence was four times higher than among people who were exposed to passive smoking at home, and prevalence was half that of people who have ever been a smoker.

The current EU air quality limits for PM2.5 is 25 micrograms per cubic metre (25 mg/m3), which is higher than the levels that the researchers noted as being linked to reduced lung function.

The researchers found that outdoor air pollution exposure is directly linked to lower lung function and increased COPD prevalence. They found that people exposed to higher levels of pollutants had lower lung function equivalent to at least a year of ageing.

The results also suggested that air pollution had much larger effects on people from lower-income households.

Air pollution had approximately twice the impact on lung function decline and three times the increased COPD risk on lower-income participants compared to higher-income participants who had the same air pollution exposure.