Efforts to cut air pollution in the past few decades have helped increase life expectancy in the general population, according to groundbreaking new U.S. research.
The study, published today in the New England Journal of Medicine, gives the most comprehensive evidence to date that may put to rest the question of whether air quality improvements can have a measurable effect on health.
"This tells us that continued efforts to improve air quality, even in only moderately polluted cities, should result in improved life expectancy," said lead author Arden Pope.
On average, reductions in fine particulate air pollution in the past few decades increased life expectancy by about five months for those living in 51 U.S. cities that researchers included in the study.
"The evidence clearly suggests that the reason we're seeing increases in life expectancy is because we have a reduction in an important risk factor, in this case air pollution, to cardiopulmonary disease generally," said Dr. Pope, who is a professor at Brigham Young University in Utah.
Although Canadian cities weren't included in the study, the findings represent promise for this country's continuing efforts to improve air quality, according to Ted Boadway, health care consultant for the Canadian Medical Association and Ontario Medical Association.
"The message is that prevention works here," he said. "In short, it's worth doing anything because if you do something, you get something."
Fine particulate air pollution is associated with an increased risk of various health issues, ranging from breathing problems to decreased lung function and heart attacks. Research has suggested that long-term exposure to fine particulate matter can dramatically increase the risk of dying from heart disease or stroke.
Fine particulate matter consists of microscopic particles and liquid droplets that can contain sulphates, nitrates and other acids, as well as organic chemicals, metals and dust. While some particulate matter occurs naturally, a major portion of it comes from industrial activities, burning fossil fuels and other human activities.
Researchers compared changes in the amount of particulate matter measured in the air in 51 U.S. cities from the early 1980s to the early 2000s and also looked at changes in life expectancy to arrive at their conclusion.
They found an overall decrease in the amount of fine particulate matter in the air was associated with an increase in life expectancy. Areas that had the largest reduction in air pollution also had the largest increase in life expectancy, the study said. Average life expectancy increased seven months for every decrease of 10 micrograms per cubic metre of fine particulate air pollution, according to the study.
"There's been some success and it seems to be paying off," Dr. Pope said. "The other encouraging aspect of this seems to suggest that further improvements in air quality will result in further improvements in life expectancy."
The researchers arrived at their conclusion by analyzing death and population data from the cities involved in the study. They also took into account additional factors that may affect life expectancy, such as smoking rates, level of education, migration, income and other demographic information, to increase the accuracy of their findings.
Although other factors contributed to an overall increase in life expectancy, researchers determined that up to 15 per cent of the boost could be attributed to improvements in air quality.
Over all, the researchers found that life expectancy in the cities studied increased by nearly three years from about 1980 to 2000. Of that, about five months, on average, could be attributed to a reduction in fine particulate air pollution.
