Long-term air pollution linked to faster lung decline in CF: London study
UK researchers cite need for national studies on environmental factors' impact
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Long-term exposure to fine particulate matter, a type of air pollution, accelerates the decline in lung function among people with cystic fibrosis (CF) living certain areas of London, according to a new study.
The research showed that CF patients exposed to higher levels of fine particulate matter experienced significantly greater lung decline over a 10-year period than those living in areas of the city with cleaner air.
“Our findings highlight the importance of addressing air pollution as a modifiable risk factor to improve long-term outcomes of people with CF, and the need for national studies of the impact of environmental factors on CF in the UK,” researchers wrote.
The study, “Impact of air pollution on lung function in cystic fibrosis over a decade in London: a UK CF Registry study,” was published in the journal Thorax.
Air pollution impacts decisions of CF patients in UK
CF is a genetic condition marked by a progressive decline in lung function, leading to serious health complications. While genetic mutations cause the disease, scientists increasingly believe that environmental factors — including air pollution — also play a role in how quickly lung function worsens in CF.
To investigate further, a team led by researchers from Imperial College London analyzed 10 years of data (2008-2017) from the UK Cystic Fibrosis Registry. The study included 393 people with CF living in London — 122 children and 271 adults — all of whom had repeated lung function tests and a registered London postcode. Lung function was measured using ppFEV1, or how much air a person can forcefully exhale in one second.
“Air pollution and the quality of the local residential environment have a substantial impact on decisions made by people with CF in the UK,” the team wrote.
Over the decade, the proportion of patients with a Pseudomonas aeruginosa lung infection, the most common CF-related bacterial lung infection, rose from 41.7% in 2008 to 62.6% in 2011, and remained above 56% through 2017. At the same time, the mean lung function dropped from 73.3% to 63.1%, an average yearly decline of 1.1%.
Clear link between fine particulate matter exposure and lung decline
The researchers linked patient addresses to pollution data from the London Air Pollution Toolkit, focusing on two pollutants: particulate matter smaller than 2.5 micrometers (PM2.5) and nitrogen dioxide.
PM2.5 particles are tiny — about 30 times smaller than a human hair — and can penetrate deep into the lungs. They mainly come from vehicles, power plants, industry, wood burning, and fires. Nitrogen dioxide mainly comes from fuel combustion, especially traffic.
The results showed a clear link between PM2.5 exposure and lung decline. By 2017, CF patients exposed to high PM2.5 levels had a mean decline in lung function of 13.3%, compared with 8.5% in those exposed to low levels. These results remained after adjusting for age at the study’s start, sex, CF genetics, height, weight, infection status, and socioeconomic background.
These findings provide valuable new evidence of the negative impact of PM2.5 exposure on people with CF.
Similar patterns were seen in key subgroups. Among people who did not change postcode, lung decline was 10.5% in the high-exposure group versus 6.2% in the low-exposure group. In adults with CF, decline was 13.1% in high-pollution areas compared with 6.7% in low-pollution areas. In children, however, lung function declined at similar rates regardless of pollution exposure (12.1% vs. 13.2%).
“Children with CF generally have higher [initial] lung function, but their developing lungs may be more susceptible to the adverse effects of air pollution, leading to greater proportional declines,” the researchers wrote.
Among patients with severe CF-causing gene mutations, those exposed to higher PM2.5 levels had a much steeper decline in lung function (18.3%) compared with those in lower-exposure areas (9.2%). However, this difference was not statistically significant, meaning it could have arisen by chance.
Unlike with PM2.5, nitrogen dioxide showed no clear link to lung function decline. Patients in high-nitrogen dioxide areas had a 9.7% decline, compared with 11.4% in low-nitrogen dioxide areas.
“These findings provide valuable new evidence of the negative impact of PM2.5 exposure on people with CF,” the team concluded. “To fully understand the impact of PM2.5 exposure on lung function in people with CF, particularly regarding age-specific susceptibility and potential interactions with other factors, further research is needed.”
The researchers also noted that 44% of participants lived in lower socioeconomic areas of London, meaning the findings “may not fully generalise to CF populations in less deprived or more rural settings.”
