Study Finds Evidence Of Causal Link Between Particulate Matter Air Pollution and Mortality

High levels of particulate matter from air pollution has been linked to an increased risk of Americans dying early, even at levels below acceptable U.S. standards, according to the findings of a new study.

Long-term exposure to particulate matter 2.5 (PM 2.5) increases a person’s risk of dying early, according to a report published last month in the journal Science Advances.

Researchers from the Harvard T. H. Chan School of Public Health say if air pollution levels were lowered, hundreds of thousands of lives could be saved.

The study used more than 16 years of data, including 68.5 million Medicare enrollees and 570 million observations, to examine the link between fine particulate matter exposure and early death. They matched participants’ zip codes with air pollution data form locations across the United States.

The findings were based on the largest dataset of older Americans, and used multiple analytical methods, including statistical methods for causal inference to draw the conclusions regarding the increased risk.

The conclusions indicate there is strong evidence to conclude a causal link between long-term PM 2.5 exposure and mortality.

Researchers report that a decrease of 10 μg/m3 of PM 2.5 would lead to a statistically significant 6% to 7% decrease in death risk. Lowering air quality standards by 10 mg/m3 would save more than 143,000 lives in only one decade they determined. That could lead to millions of lives saved over the course of 60 to 70 years.

PM 2.5 is air pollution particles the size of 2.5 micrometers or smaller, or roughly 70 times smaller than one human hair. These are a mixture of soot and dirt so small that the particles are easily inhaled into the lungs and move to the blood stream, leading to health side effects.

Prior research has shown PM 2.5 exposure can increase a person’s risk of stroke and leads to the deaths of more than 30,000 Americans every year. Even at short-term exposure levels PM 2.5 may increase a person’s risk of cardiac arrest, especially among the elderly.

Even at moderate levels, air pollution can cause lung damage similar to that seen among people who have smoked cigarettes for decades.

Researchers note that if U.S. air quality standards met the limits set by the World Health Association air pollution guidelines for fine particulate matter 2.5, more than 140,000 lives could be saved over 10 years.

“Our results raise awareness of the continued importance of assessing the impact of air pollution exposure on mortality,” the researchers concluded. “Most epidemiological studies must rely on confidential patient data to provide evidence on adverse health effects of environmental exposures on outcomes and also focus on populations that cannot be studied using administrative data. We hope this work will help researchers and policy makers, particularly as revision discussions of national PM_2.5 standards are underway.”