Air pollutants linked to emphysema risk

3 minute read

Long-term exposure to ambient air pollutants, especially ozone, is a significant risk factor in developing emphysema

Living near a busy road significantly increases a person’s risk of developing emphysema, researchers say.

According to a US longitudinal study, recently published in JAMA, constant exposure to air pollution, especially ground ozone, has been confirmed as a major risk factor for developing the disease.

Ground ozone is not an emission, but a chemical reaction which occurs when the oxides of nitrogen (80% from vehicle emissions) combine with volatile organic compounds and sunlight.

In warmer temperatures, levels of this ozone have been found to increase, particularly near sources of pollution, such as major motorways. 

Ozone, which naturally occurs at a level of four parts per billion is not considered harmful to health, however the American Lung Association said higher levels than this have been known to cause premature death, compromised lung function and cardiovascular issues.

The 18-year study included more than 7,000 individuals drawn from the Multi-Ethnic Study of Atherosclerosis (MESA) Air and Lung studies. The participants lived across six metropolitan regions in the US, and almost half reported they had never smoked.

At baseline, the prevalence of emphysema was 3% across the cohort as determined by a CT scan, increasing to almost 20% at the 10-year follow-up scan.

The study found the annual levels of ozone measured across US cities were between 10 and 25 parts per billion.

“Because long-term concentrations of ozone at current levels were strongly and consistently associated with both progression of emphysema and decline in lung function in this study, more effective control strategies to reduce ozone concentrations may be needed to protect lung health,” the authors said.

“We were surprised to see how strong air pollution’s impact was on the progression of emphysema on lung scans, in the same league as the effects of cigarette smoking, which is by far the best-known cause of emphysema,” Professor Joel Kaufman, co-author from the University of Washington and epidemiologist, said.

Rates of chronic lung cancer are continuing to rise in the US and Professor Kaufman said it was increasingly recognised that the disease occurred in non-smokers.

“We really need to understand what’s causing chronic lung disease, and it appears that air pollution exposures that are common and hard to avoid might be a major contributor,” he said.

In Australia, air pollutants such as nitrogen and sulphur dioxide are regulated by the National Environmental Protection Measures (NEPM), but there is currently no annual limits set for ground ozone.

In addition, the NEPM only measures air pollution in population centres with more than 25,000 people, meaning the levels in towns with high-level industry pollution, such as in the Hunter Valley in New South Wales, remain unaccounted for.

The limits of ground ozone will be reviewed this year under the Australian National Environmental Protection Council. The proposed limit would be 65 parts per billion over an eight-hour period.

But Doctors for the Environment Australia said the limit needs to be at least 28% lower than that to come into line with previous research, and provide better protection for public health.

JAMA 2019, 13 August

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