Lower Air Pollution Linked To Higher Mortality
December 4, 2012

Lower Air Pollution Linked To Higher Mortality Says Harvard Study

Connie K. Ho for redOrbit.com — Your Universe Online

A new study from the Harvard School of Public Health found that a decrease in the air pollution levels is linked to improved life expectancy in the United States. The researchers discovered the connection in 545 different counties between 2000 and 2007. They believe that it is the biggest study of its kind to date, and could eventually impact general public health in the U.S.

The findings were recently published in the online edition of the journal Epidemiology.

"Despite the fact that the U.S. population as a whole is exposed to much lower levels of air pollution than 30 years ago — because of great strides made to reduce people's exposure — it appears that further reductions in air pollution levels would continue to benefit public health," commented the study´s lead author Andrew Correia, a PhD candidate in the Department of Biostatistics at HSPH, in a prepared statement.

With the project, the team of investigators wanted to better understand how fine particles of matter in the air, approximately 2.5 micrometers or less in diameter, could affect people´s health. Some previous studies have shown how exposure to these small particles of air pollution can lead to cardiopulmonary disease and mortality. Other studies have shown that a reduction in air pollution is linked to decrease in negative health affects as well as an increase in life expectancy.

The results of this current experiment showed that the decrease in the concentration of the particulate material in the air since 2000 was still improving life expectancy. Overall, air pollution has been decreasing in the U.S. since 1980. However, in 2000, the rate of decline began to slow, and the researchers wanted to study whether the decreases in the particulate matter levels since 2000 were still leading to a boost in life expectancy.

This study was a follow-up of a 2009 experiment featured in the New England Journal of Medicine. The project in 2009 looked at how air pollution was related to a rise in life expectancy in 211 urban counties. With more recent data, the new study was able to examine more counties, in both rural and urban settings. The new study showed that there was a strong correlation between the drop in air pollution and the boost in life expectancy in urban areas that were more densely populated as opposed to locations that were more rural. The team of investigators also found that women were more likely than men to reap benefits from the decline in air pollution.

Researchers believe that the composition of particulates may have affected the reduction in urban areas compared to more rural locations.

"Since the 1970s, enactment of increasingly stringent air quality controls has led to improvements in ambient air quality in the United States at costs that the U.S. Environmental Protection Agency has estimated as high as $25 billion per year,” concluded the study´s senior author Francesca Dominici, professor of biostatistics at HSPH.

“However, the extent to which more recent regulatory actions have benefited public health remains in question. This study provides strong and compelling evidence that continuing to reduce ambient levels of PM2.5 prolongs life."