Outdoor air pollution is directly linked to decreased lung function and increased prevalence of chronic obstructive pulmonary disease (COPD), according to a new paper published on 9 July in the European Respiratory Journal (1). Lung function is known to decline with age, but these new findings suggest air pollution may significantly contribute to lung ageing.
Surprisingly, few studies have assessed the health effects of air pollution on the lungs, says senior author Prof Anna Hansell from the University of Leicester in the UK. So, in this study, the researchers examined data from the UK Biobank study on more than 300,000 people to assess whether exposure to air pollution is linked to changes in lung function and the risk of developing COPD (an umbrella term encompassing several progressive lung diseases including emphysema, chronic bronchitis).
The UK Biobank, set up in 2006, has become an invaluable tool for researchers, containing genetic data on 500,000 people between the ages of 40 and 69 living in the UK, as well as data on their lifestyle and body type of each individual. In addition, clinical data based on saliva, blood, and urine samples are available, and in some cases, MRI scans.
The international team of researchers obtained data on participants who previously filled out detailed health questionnaires as part of the UK Biobank data collection. In addition, each volunteer underwent lung function tests using spirometry, which measures how much air can be breathed out in one forced breath.
They first used a validated air pollution model to estimate the levels of pollution people were exposed in their homes when they enrolled in the UK Biobank study. And then determined whether long-term exposure to higher levels of the air pollutants affected lung function. This included three types of air pollutants — particulate matter (PM10), fine particulate matter (PM2.5) and nitrogen dioxide (NO2) — emitted by car and other vehicle exhausts, power plants, and industrial emissions. The authors also accounted for age, sex, body mass index (BMI), household income, education level, smoking status, and exposure to secondhand smoke.
Based on their analysis, an average annual increase of five micrograms per cubic meter of particular (PM2.5) results in an associated decrease in lung function equivalent to two years of ageing. Furthermore, in areas with PM2.5 concentrations above the annual average guidelines designated by the World Health Organization (WHO) — ten micrograms per cubic meter — the COPD prevalence was four times higher than among people exposed to passive smoking at home and 50 per cent lower in people with a history of being a smoker.
The findings also suggest that air pollution had a greater impact on lower-income participants compared to higher-income participants exposed to the same air pollution. More specifically, around twice the impact on declining lung function and increased COPD risk was three-fold higher. But the authors say further investigations are still needed to verify this.
In Europe, the effects of air pollution on health are higher than the global average. And children are even more vulnerable than adults to environmental risk factors. Another recent study found environmental pollutants have a large impact on children’s health in Europe. Furthermore, it is estimated that dirty air leads to 154 early deaths per 100,000 people in Germany with an average reduction in life expectancy of 2.4 years; whereas, in the UK these figures are 98 deaths premature deaths per 100,000 and reduced lifespan of 1.5 years.
This latest study adds to a growing body of research highlighting the major health risks of air pollution. The current EU air quality limit for PM2.5 is 25 micrograms per cubic meter, which is much higher than the values that have now linked to reduced lung function. This suggests stronger policies and further legislation are needed If there is any hope of significantly reducing these adverse health effects of air pollution. And of course, fossil fuels will need to be replaced with clean energy sources.
“The findings of this large study reinforce that exposure to polluted air seriously harms human health by reducing life expectancy and making people more prone to developing chronic lung disease”, says President of the European Respiratory Society Professor Tobias Welte, who was not involved in the study.
Adding that “access to clean air is a fundamental need and right for all citizens in Europe. Governments have a responsibility to protect this right by ensuring that maximum pollutant levels indicated by the World Health Organization are not breached across our cities and towns. Breathing is the most basic human function required to sustain life, which is why we must continue to fight for the right to breathe clean air.”
(1) Doiron, D. et al. Air pollution, lung function and COPD: results from the population-based UK Biobank study. European Respiratory Journal (2019). DOI: 10.1183/13993003.02140-2018