Harvard Study Says Cleaner Air Adds Five Months to Life Expectancy

clean air sky

Fine particulate air pollution isn’t a subject the average American knows a great deal about. Yet, it has a major impact on how long you will live. Scientists refer to it as PM2.5 — particulate matter less than 2.5 microns in diameter, which means a piece of matter less than ¼ the width of a single strand of your hair.

Despite its tiny size, it packs quite a punch. According to the American Lung Association, these fine particles cause serious health problems such as asthma, bronchitis, and other lung diseases at low concentrations. Fine particulate matter is also known to cause premature death in elderly people who already have heart and lung disease. In fact, the Association has gone on record saying, “Tens of thousands of premature deaths each year are attributed to fine particle air pollution.”

Particulate matter in the air comes primarily from the combustion of fossil fuels to operate cars, buses, and diesel trucks. It can also come from factory emissions of sulfur and nitrogen oxides and other organic compounds that change into sulfate and nitrate when they hit the atmosphere. Construction and landfill dust is another offender, as is the smoke from wood burning stoves and fireplaces.

There have been a number of epidemiological studies that have investigated the link between living in geographic areas with high fine particle concentrations in the air and life expectancy. The most recent is a collaborative effort between researchers at Brigham Young University and Harvard School of Public Health entitled “Fine-Particulate Air Pollution and Life Expectancy in the United States”, which appeared in the January 22nd edition of the New England Journal of Medicine. What’s significant about this study is that the findings indicate that of the almost three years increased life expectancy that residents of 51 U.S. cities have enjoyed over the last two decades, five months of that increase is thanks to cleaner air.

The cities that were chosen to be part of the study were part of a larger group studied by the EPA from 1979 to 1983. During those years, the agency maintained the Inhalable Particle Monitoring Network, which calculated the average concentration of PM2.5 in the air of 61 cities.

After 1983, there was no longer any monitoring network in existence that systematically collected PM2.5 data until the EPA issued the National Ambient Air Quality Standard for PM2.5 in 1997. This new standard required cities to begin measuring PM2.5 in 1999.

The researchers who worked on the Brigham Young and Harvard study extracted the daily PM2.5 data from the EPA’s Aerometric Information Retrieval System database for 1999 and the first three quarters of 2000, and averaged it if they had more than 50 percent of the samples and 45 or more total sampling days for at least one of the two corresponding quarters in each year. There were 51 metropolitan areas with matching PM2.5 data for the early 1980s and the late 1990s.

The scientists then used advanced statistical models to account for other factors that could affect average life spans, such as changes in population, income, education, migration, demographics, and cigarette smoking. After all of the analysis, what they discovered was that the most polluted cities at the beginning of the testing period that worked to significantly clean up their air added almost 10 months to the average resident’s life. On average, Americans were living 2.72 years longer at the end of the two-decade study period; up to five months of that increase was the result of the decrease in fine particulate air pollution.

The scientists also found there was an increase in life expectancy in cities that initially had relatively clean air but worked to make additional improvements in air quality. They concluded that there are continuing benefits to be had from ongoing efforts to reduce air pollution.

Reference was made in the “Discussion” section of the study to the fact that it was a “simple, direct, and transparent exploration of the association between life expectancy and air pollution,” that wasn’t able to examine other population-based factors that affect longevity like the access to quality medical care, better diets, and healthier life styles. However, even if you take that shortcoming into consideration, you can’t ignore the clear message that this study sends — improvements in air quality contribute to measurable improvements in life expectancy.

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