Is St. Louis really that bad for allergies?

ST. LOUIS - As the end of summer draws near, fall allergy season approaches, and in the St. Louis region ragweed and mold lead the charge.

FOX 2 Meteorologist John Fuller says late summer marks the beginning of ragweed season. “In August,” he said. “A lot of weeds, including ragweed, become more proliferous in the atmosphere. They cause eye irritation as well as sneezing.” 

St. Louis ranked 67th among the top U.S. cities for allergy intensity in the AAFA’s annual ranking this year. Frequent rain and stagnant air lead to higher mold counts, which can persist year-round. The most common allergens in the area include mold, tree pollens, grasses, and weeds. 

“Spring is the worst for tree pollen because the trees are blooming or the flowers are blooming in the trees so that pollen becomes more pronounced,” Fuller said. “Mold’s just about any time of the year when the air is stagnant and you get temperatures in that conducive range.”

The conducive range is from about 70 to 80 degrees consistently when nighttime lows don't fall off very much.

Fuller described the green dust from trees like pine and ash that coats cars and decks in early spring as a contributor to severe reactions. 

Air quality also plays a role in exaggerating allergic symptoms. He noted that wildfire smoke earlier in the summer worsened conditions. “Those air quality levels were very high for particulates when we got the smoke from the wildfires in Canada early in the summer,” he said. “And you could see it in red and orange sunsets because it scatters the sunlight.”

In late summer, ragweed and plantain become more active. In the fall, mold starts to pick up again because of leaf mold. They sit on the ground and moisture accumulates around them.  

Fuller says that there are two separate groups. Allergic reactants like tree pollens, mold, or weeds, and then air pollution, or the combination of particulate and ozone and hydrocarbons.

Some neighborhoods are more affected than others. “Webster Groves, Kirkwood because they're densely forested or have dense tree populations, and Ladue,” Fuller said. “Near the airport... I'm thinking that some of your hydrocarbons may spike because you have planes taking off all the time and you also have vehicle traffic.”

He added that areas like Metro East, Granite City, East St. Louis, and downtown St. Louis face additional challenges. “Their problem is a result of our contribution to the overall air quality and it drifts their way,” he said.

To protect against allergens, Fuller recommends improving indoor air circulation. “Just run the fan because that circulates the air in the house and pulls it through the air filter in the furnace and filters out a lot of the mold and pollen and dust,” he said. “But make sure you have a good filter.”

“If you go cheap on the filters, that smaller matter will make it through the filter and back into the house,” he said. “You'll be breathing the same old stuff.”

For those with chronic issues, Fuller suggests seeing a specialist. “If you really have chronic issues, you may want to go see an allergist to be tested for what you're allergic to so you can avoid it,” he said. “Some people just like over-the-counter products like Zyrtec, Claritin, and then if those don't work sometimes they give you shots.”

For additional guidance on allergies, FOX 2 has an allergy index that is updated every day. You can also check out an interactive map of air quality by clicking here.