This study by Canadian and American researchers — the largest and longest of its kind — examined the association between exposure to four key air pollutants and the development of emphysema. The pollutants include nitrogen oxide, ground-level ozone (such as those produced by fossil fuels as opposed to ozone in the atmosphere, which is too far removed to affect people), black carbon, and fine particulate matter (also sourced from fuel combustion, among other sources like industrial waste).
Emphysema is a form of chronic obstructive pulmonary disease (COPD), a disease typically associated with smoking. Patients with emphysema have damaged air sacs in their lungs, thereby obstructing the transfer of oxygen to the body. But now we know that exposure to air pollution is also a risk factor.
The American Lung Association’s State of the Air report states that 4 in 10 Americans are living in areas with unhealthy levels of air pollution, while Canadian government stats report that some 14,000 suffer premature deaths every year due to air pollution.
Long-term research is important for public health officials as it helps them to make informed decisions about how policy should be shaped. This complex decision-making process can go a long way toward making our societies cleaner, safer, and healthier for their inhabitants.
Effects of ozone could be comparable to heavy cigarette smoking
Some 7,000 study participants with a 47/53 male-to-female split and ages ranging from 45 to 84 were observed for a decade on average (the total study period covered 2000-2018). All participants were from one of six major U.S. cities like New York or L.A., and the prevalence of pollution was estimated according to published data on each city.
The participants themselves were routinely examined using CT scans to check for emphysema, and pollution rates were subsequently compared to this data to figure out whether there was a link between them.
The study concluded that higher baseline levels of all four pollutants had a small but statistically significant increase in emphysema risk, independent of other factors. Ozone was particularly suspect, being the only pollutant at both the baseline and follow-up period to be associated with a decline in a measure of lung functionality known as forced expiratory volume 1 (FEV1). FEV1 measures the max amount of air a person can expel in one second by blowing forcefully, a test that is used to measure the severity of diseases like COPD.
An increase of just three parts per billion in ambient ozone concentrations over 10 years was found to be so damaging it was compared by senior author R. Graham Barr to 29 years of smoking a pack of cigarettes a day and three years of aging.
“These findings matter since ground-level ozone levels are rising, and the amount of emphysema on CT scans predicts hospitalization from and deaths due to chronic lower respiratory disease,” said Barr in an interview with the University of Washington.
Chronic lower respiratory disease is a catchall term for emphysema, bronchitis, COPD, and asthma.
Ground-level ozone levels are expected to increase over the coming decades due to climate change because the pollutant is produced when fossil fuel pollutants react with UV light, a process which is accelerated by heatwaves. Barr noted that it remains unclear what level (if any) of ozone is safe for human health.
“These findings may offer one explanation for why emphysema is found in some people who never smoked,” commented James Kiley, a field expert who was not involved in the study, in UofW’s press release. “It’s important that we continue to explore factors that contribute to emphysema, particularly in a large, multi-ethnic group of adults.”.