Air pollution shortens lives: MIT study

A study released earlier this week indicates that airborne pollution in China may have shortened the lives of 500 million Chinese by 2.5 billion years. The paper, published in PNAS on Monday, examined pollution data and death records to see whether coal burning, long a source of air pollution, could have damaged public health across northern China in the 1990s. It does. The findings raise concern for developing countries.

The nose, mucus in the esophagus and cells in the lungs all filter foreign substances to facilitate clean breathing. But some pollutant particles can overwhelm the body’s natural defense systems, however, causing inflammation in the lungs. This inflammation could result in breathing difficulties, exacerbate preexisting conditions and, in extreme cases, cause death.

Michael Greenstone, an economist at Massachusetts Institute of Technology and a primary author of the study, says finding answers has been extremely difficult, because simply comparing pollution levels and health in different locales can be misleading. For one thing, people often move from place to place and experience varying levels of pollution, so it is not safe to assume that all have had the same exposure.

From 1950 to 1980 the Chinese government was in a period of socialist transformation. During this time the “Huai River policy” provided free coal for heating homes and offices north of the Huai River, which runs west to east across eastern China. Meanwhile budget constraints kept free coal from being provided south of the river. At the same time, government rules restricted a family's ability to move, so that many lived in one location for decades.

By examining rates of mortality and respiratory-related illnesses on both sides of the river, Greenstone’s team identified a difference: life expectancies are lower and pollution concentrations are higher north of the Huai, where coal burning was widespread.

To make these connections, Greenstone and his team examined pollution data from sites across the country for the years 1981 to 2000. They then collected mortality data from China's Disease Surveillance Points, 145 sites chosen by the government to accurately represent the wealth and geographic dispersion of the populace.

The results estimate that lifelong exposure to 100 micrograms of “total suspended particulates,” or TSPs, (minuscule solid particles floating in the air, such as pollutants) per meter of air cubed will shorten a person’s life by three years, on average.

As more countries in Asia and Africa power toward industrialization, air pollution becomes an increasing concern. Developing countries are really trying to strike the right balance between economic growth to confront poverty and environmental quality and public health,” Greenstone says. “I think this study will help them—it shows a relationship between pollution and health.”