Inhaling air pollutants can trigger breathing problems, such as asthma. Asthma itself can be triggered by allergies. So physicians have observed that allergies, asthma and air pollution go hand in hand in hand. Still, scientists weren’t exactly sure why they were linked. New data now provide clues.
During an asthma attack, inflammation causes the inside of small airways in the lung to swell. This narrows those passageways, reducing how much air can move through them in any given breath. This means people will have a hard time drawing in enough air to breathe comfortably.
Researchers have now linked a common family of air pollutants to a breakdown in cells involved in the immune system. It plays a role in allergies. The cells they focused on are called T-regs (short for T-regulatory cells). Normally, they help protect the body by controlling swelling caused by inflammation.
“T-regs are peacekeeper cells,” explains Kari Nadeau of Stanford University. But in people with asthma, she explains, those T-regs don’t work quite right. Nadeau is both a physician and a biochemist (a scientist who studies how chemicals affect cells) in Palo Alto, Calif.
Her team studied pollutants known as polycyclic aromatic hydrocarbons, or PAHs. These form when fuel doesn’t burn completely. They may be spewed by diesel and gasoline engines, wood fires, furnaces, wildfires and barbecue grills.
To probe the connection between PAHs and T-regs, Nadeau and her coworkers looked at many different types of data. They collected blood tests, lung measurements and other health information from more than 150 children in Fresno. This California city has high levels of air pollution. The scientists also measured PAHs in the air in and near homes of these children.
T-regs didn’t work as well as they should in kids living in heavily polluted areas. Children exposed to high levels of PAH also were much more likely to have asthma. Nadeau presented her team’s new findings in February at a meeting of scientists who study allergies, asthma and the body’s immune system.
“I think this is a very interesting and thought-provoking study,” said Todd Rambasek. He’s an allergist practicing in Lorain, Ohio. Previous studies have linked air pollution with asthma, but they did not look specifically at PAHs, he told Science News.
allergist A doctor who diagnoses, treats and studies allergies in people.
allergy A damaging immune response by the body to a substance like air pollution or pollen.
asthma A condition that causes difficulty in breathing, often triggered by an allergy.
immune system The body’s natural defense system. It is used to protect against infections or toxic substances, such as pollutants.
inflammation A physical condition in which part of the body becomes reddened, swollen, hot and/or painful.