Results from a two-decade study that looked at 2,000 kids in 5 cities in Southern California was recently published in the New England Journal of Medicine. Its findings remind us once again of the importance of clean air; remember, air pollution now kills more people than AIDS and malaria combined, and is now the world’s biggest environmental health risk with 7 million deaths per year. In fact, the World Health Organization now puts air pollution in the same category as tobacco smoke, UV radiation and plutonium!
The researchers found that the marked decline in air pollution in the region since the early 1990s has had a “statistically and clinically significant improvements” in children’s lung function and growth. In fact, the number of school-age kids with "abnormally low lung faction" dropped by more than half between the 1994-1998 group (7.9% with abnormally low lung function) and the most recent studied one, from 2007-2011 (3.6%). This seems to track fairly closely the amount of particulate matter pollution (PM2.5) over the same period, from 28 micrograms per cubic meter on average annually in 1994 to 13 micrograms per cubic meter in 2011.
“We can now turn that around and say that improving air quality leads to better health,” said W. James Gauderman, professor of preventive medicine at USC’s Keck School of Medicine and lead author of the study with eight other researchers. “This is one of the first good news studies ever about air pollution.”
Field teams took repeated measurements of students’ ability to breathe as they grew from age 11 to 15. While air quality monitoring stations logged pollution levels at each location, researchers compared students growing up from 2007 to 2011 to two previous groups of children whose lungs were tested from 1994 to 1998 and from 1997 to 2001.
As air quality improved, the number of children with abnormally low lung function — less than 80% of the lung capacity expected for their age -- dropped by more than 4 percentage points, from 7.9% in the mid-1990s to 3.6% in 2011. The children’s four-year lung growth improved by more than 10% over the same period. (source)
Over the time period when the study took place, levels of nitrogen dioxide (NOx) dropped 33% across the five cities covered and fine particle pollution (PM2.5) fell by 47%. These were the two biggest factors for lung function. Reductions in ozone levels did not seem to have the same impact (though less ground-level ozone pollution is obviously a good thing too).
Teenagers between 11 and 15 were studied because their lungs grow quickly, and improvements that take place during that period are likely to stay with them for the rest of their lives.
A K-8 school principal in Long Beach notices the difference in air quality improvements, saying that nowadays she sees fewer kids with respiratory distress.
While things have improved, and the US is doing well compared to many places around the world, there's still a lot of work to do. Few things are more important to human health than breathing, so let's make sure that clean air is available to all (outside of the US too, or course! In fact, there are more low-hanging fruits there, like tightening rules on diesel).
Via New England Journal of Medicine, LA Times