Everyone knows that air pollution is bad for you and your child's health. It can lead to chronic respiratory problems such as asthma, as well as hay fever, eye irritation, and heart disease. But now ear infections have been linked with pollution as well.

Dr. Nina Shapiro: Ear infections are the most common problem seen in children, and they are actually considered a respiratory illness. My colleague, Dr. Neil Bhattacharyya, associate professor at Harvard Medical School, and I examined the effect of air pollution on ear infections. We looked at ear infection data on 126,000 children from 1997-2006 (obtained from the National Health Interview Survey), and cross-referenced this with the air pollution data published by the Environmental Protection Agency (EPA) for the same years. We chose this time period to reflect the benefit of the revised Clean Air Act of 1990, authorizing the EPA to limit amounts of pollutants emitted by factories, chemical plants, and cars.

The good news is that the most significant pollutants (carbon monoxide, sulfur dioxide, nitrous dioxide, and particulate matter) all declined significantly for each year we studied. At the same time, the frequency of ear infections in children also declined, also significantly. To make sure this wasn't a coincidence, we looked at a "non-respiratory" condition (seizures) in the same population over the same time period, and there was no change in the frequency.

We presented our work at the annual meeting of the American Academy of Otolaryngology -- Head and Neck Surgery on October 7, 2009, in San Diego, CA. While our results are important (and positive!), the work is not done. We need to follow the levels of pollutants, as well as other environmental factors affecting our health.

Dr. Nina Shapiro is a graduate of Harvard Medical School, and she completed her residency in ear, nose, and throat surgery at Harvard. She is an Associate Professor and Director of Pediatric Ear, Nose, and Throat at the Mattel Children's Hospital at UCLA. She has treated tens of thousands of children with ear problems, sleep problems, and breathing problems. She lives with her husband and two young children in Los Angeles.