Using a CT scan, researchers were able to see that that exposure to each of the pollutants was associated with the development of emphysema, a lung condition that causes shortness of breath, and is usually associated with cigarette smoking. It’s a debilitating chronic disease that shrinks the amount of oxygen that reaches your bloodstream.
The patients were all healthy when they started the study, and researchers controlled for factors that could compromise lung health, including age and whether the person was a smoker or was regularly exposed to secondhand smoke.
The strongest association between a pollutant and emphysema was seen with exposure to ozone, which was the only pollutant associated with an additional decline in lung function.
Ground-level ozone is the part of smog that you can’t see. It’s colorless and it comes from the photochemical transformation that occurs when pollutants interact with sunlight.
“The increase in emphysema we observed was relatively large, similar to the lung damage caused by 29 pack-years of smoking and 3 years of aging,” said Dr. R. Graham Barr, the Hamilton Southworth professor of medicine and epidemiology at Columbia University Irving Medical Center and a senior author of the paper. One pack-year means smoking a pack of cigarettes a day for a year.
Ambient concentrations of fine particulates and nitrous oxide, but not ozone, decreased significantly over the study period, the researchers said.
“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.
With the climate crisis, there could be much higher levels of ground-level ozone in the future.
Stephen Holgate, a special adviser on air quality at the Royal College of Physicians in the UK, said that while it had been known for some time that air pollution and cigarette smoking accelerates the development of emphysema in those who are genetically susceptible to it, this study showed that the same was true in the general population. Holgate was not involved in the research.
“This important study adds to the massive evidence base that air pollution, in this case specifically ozone, is harming people, especially those who are vulnerable with co-existent lung disease,” he told the Science Media Centre in the UK.
Holgate noted that the study did have some limitations, including the fact that it didn’t measure air pollution indoors, where most people spend their time.
Studies like this essentially measure pollution as if you spent all your time on your front porch, he said. It doesn’t take into account the time you spend in your house or your office, but it’s a good general measure that shows exposure to pollution increases lung problems in the general population.
Kaufman says he hopes people will look at research like this and will use it to encourage their leaders to work on better environmental policies and pay attention to their fossil fuel consumption.
“The big surprise was the magnitude of this, putting pollution in the same league as cigarette smoking,” said Kaufman. “Cigarette smoking is by far the best known cause of emphysema. The fact that ozone is in the same league was definitely a surprise.”