Story at a glance
- Scientists found that people exposed to particulate matter over 2.5 micrometers were more likely to report vision problems.
- The research focused on two pollutants: nitrogen oxides and nitrogen dioxide.
A new study adds to the growing volume of scientific literature connecting eyesight problems with increased air pollution.
For the study, published Monday in the British Journal of Ophthalmology, U.K. scientists observed more than 115,000 volunteers between the ages of 40-69 to gauge if increased amounts of nitrogen dioxide and nitrogen oxides were linked to age-related macular degeneration (AMD) or the deterioration of the retina that results in impaired vision.
Researchers measured retina damage with both volunteer reports and spectral-domain optical coherence tomography, a scan that uses light to examine the human eye.
Amounts of nitrogen oxides and dioxide were measured in particulate matter. Researchers cross referenced the addresses of each participant with the air pollution estimates recorded in national databases.
Nitrogen dioxide is largely a product of man-made traffic and industrial activity. Nitrogen oxides are produced during combustion processes, both from natural and human sources.
When controlling for potential variables, such as smoking or prior health problems, the results indicate that the participants who were exposed to a higher volume of fine ambient particulate matter — or tiny particles of air pollution — reported more eyesight problems.
Specifically, participants who were frequently exposed to particulate matter less than 2.5 micrometers, commonly denoted as PM2.5, were 8 percent more likely to report having AMD.
Additionally, researchers found that higher PM levels were associated with thinner pigmented retinal layers.
“Our results showed that greater ambient PM2.5 exposure was associated with increased odds of AMD and corresponding retinal thicknesses (specifically photoreceptor sublayer and RPE),” the researchers wrote. “Overall, our findings suggest that ambient air pollution, especially fine PM or those of combustion-related particles, may affect AMD risk.”
The U.S Environmental Protection Agency notes that particulate matter less than 2.5 micrometers is especially damaging to human health, since it can easily enter the body.