Long-Term Exposure to Ozone Increases Cardiovascular Mortality Risk

Long-term exposure to ozone can lead to increased risk of respiratory or cardiovascular mortality in some adults, according to research published in the American Thoracic Society’s Journal of Respiratory and Critical Care Medicine.

Researchers found that every additional 10 parts per billion (ppb) of ozone that an adult is exposed to increases risk of lung disease mortality by 12%, cardiovascular disease mortality by 3%, and all-cause mortality by 2%.

Risk of death was highest among individuals with diabetes (16%), dysrhythmias, heart failure, and cardiac arrest (15%), and chronic obstructive pulmonary disease (14%).

“About 130 million people are living in areas that exceed the National Ambient Air Quality standard,” said study co-author Michael Jerrett, PhD, chair of environmental health sciences at UCLA, during a press release. “While ozone has decreased in the US, the reductions are not nearly as big as decreases in other pollutants, and elsewhere in the world, ozone is a growing problem.”

The study began in 1982 and included participants from all 50 states. Researchers analyzed data from 670 000 records in the American Cancer Society Cancer Prevention Study. They matched cause of death during a 22-year period with US Environmental Protection Agency and Centers for Disease Control air quality data.

More than 237 000 deaths were recorded throughout the study. Researchers included fine particulate (PM_2.5) pollution and nitrogen dioxide (NO₂) pollution, which have both been linked to premature mortality, in their calculations. They also adjusted for behavioral and demographic factors including smoking status, alcohol use, weight and diet, poverty, and race.

The association between ozone and mortality began at 35 ppb, but researchers noted that many communities are actually above this level. Therefore, reducing ozone would not only reduce the negative effects of climate change, but also have immediate health benefits.

Researchers were surprised that near-source PM_2.5 caused by traffic was more strongly associated with cardiovascular disease mortality than regional PM_2.5, which is cause by fossil-fuel burning and secondary formation of particles in the atmosphere.

Michelle Turner, PhD, lead author and research fellow at the McLaughlin Centre for Population Health Risk Assessment in Ottawa, Canada and the Centre for Research in Environmental Epidemiology ISGlobal Alliance in Barcelona, Spain, noted that the larger-sized study provided a clearer picture of pollution’s harmful effects In the past, a smaller-sized study with a shorter follow-up found ozone to be associated with a 4% increase in respiratory deaths.

“The burden of cardiovascular and respiratory mortality from ozone may be much greater than previously recognized,” she said.

References

1. American Thoracic Society. Long-term Ozone Exposure May Increase Lung and Cardiovascular Deaths. January 20, 2016. http://www.thoracic.org/about/newsroom/press-releases/journal/2016/long-term-exposure-to-ozone-may-increase-lung-and-cardiovascular-deaths.php. Accessed January 26, 2016.
2. Turner MC, Jerrett M, Pope A, et al. Long-term ozone exposure and mortality in a large prospective study. Am J Respir Crit Care Med. 2015. doi: 10.1164/rccm.201508-1633OC.