Wildfire smoke can worsen allergy symptoms

Have your spring allergies spread into summer? Does it seem as if your allergy symptoms are getting worse?

It’s not your imagination, and climate change is to blame, according to otolaryngologist Edward F. Caldwell, MD, who practices at Cape Cod Ear, Nose and Throat Specialists in West Tisbury, Hyannis and Mashpee.

The warming climate is altering the traditional spring-summer-fall cycles of tree, grass and weed pollens on Cape Cod and the Islands, along with proliferation of mold spores, he said.

Hotter temperatures year-round, moderated by the ocean waters surrounding the region, means the spring tree pollen season has gotten longer, as has the fall weed pollen season, he said.

“The distinction between the seasons has gotten less,” Dr. Caldwell said. “Mold used to be two to three seasons, now it’s year-round. Mold generally releases their spores when there’s a significant change in temperature.”

Plants that didn’t used to grow in the Northeast have spread northward with warmer temperatures, and pollen from them in Connecticut and New York blow onto Cape Cod, Nantucket and Martha’s Vineyard, he said. Some more tropical plants are introduced locally by home gardeners. He cited the palm trees planted at the Margaritaville Resort Cape Cod in Hyannis.

A March 31, 2025, American Lung Association article said seasonal allergies affect a third of adults and a quarter of children, and climate change is adding to the problem. The article pointed out that:

• Compared with five decades ago, pollen season lasts three weeks longer.
• Air levels of the greenhouse gas carbon dioxide is causing trees and other plants to produce 20 percent more pollen.
• New varieties of pollen are affecting people who previously had no seasonal allergies.
• Floods, hurricanes and other weather changes are increasing the growth of mold.

Wildfires, Pollution and Other Co-Allergens

Smoke from Canadian wildfires, air pollution from combustion and ground-level ozone are not allergens, but they make allergy symptoms worse, Dr. Caldwell said, calling them co-allergens. They all result from, and/or contribute to, climate change.

Climate change fosters conditions promoting wildfires in Canada and around the world, Dr. Caldwell said. These fires release smoke particulates that irritate eyes and respiratory tracts. According to the Centers for Disease Control and Prevention, wildfire smoke is potentially harmful to people with lung diseases, diabetes, heart disease or pregnant, as well as children and animals.

“Wildfires are becoming more common,” Dr. Caldwell said. “The last three summers, we had significant smoke from wildfires. It has to do with the fact that these fires (in Canada) don’t go out. They disappear (smolder underground) in winter, then pop back up in the spring.”

Pollutants, including fossil fuels burned in vehicles, factories and power plants, chemically react in the presence of sunlight to form ozone, a powerful respiratory irritant, according to the Environmental Protection Agency. Ground-level ozone blows into the area from the west, but also results from car exhaust during heavy traffic days in the summer on Cape Cod, Dr. Caldwell said.

“It’s a multi-pronged problem,” he said. “Then you have some ozone in there; it triggers bronchial spasms. People with asthma who were getting by with albuterol now are needing steroids.”

Even some foods can be co-allergens. Dr. Caldwell said. If someone is allergic to ragweed, for example, eating strawberries can increase symptoms.

How to Cope

“If you have significant respiratory problems, stay indoors,” he said.

For some allergy sufferers, immunotherapy – a series of allergy shots – can help.

To determine what allergens may be troubling you, a specialist can do a test. These involve putting a tiny amount of an allergen into your skin. If you develop a small hive as a reaction, you’re allergic to that substance. According to the American Academy of Allergy, Asthma and Immunology, a mild reaction similar to a mosquito bite occurs within 20 minutes and fades shortly afterward. These tests are best done in a doctor’s office to reduce the rare chance of a serious reaction.