"They're at a historic level, never been as high since they've been being measured for the past 15 years," Caplan said.
Dr. Joseph Leija, allergist, wrote tweeted, "Weeds - Moderate; Mold - Very High - air quality alert! Ragweed -- Low."
Tuesday is one of several days in a row in which Chicago's mold count has been dangerously high. A high mold count usually ranges between 13,000 and 50,000. On Tuesday, the count was at 64,000- but over the past few days it's been as high as 125,000.
That means people with allergies could experience itchy throats, runny noses and grogginess.
"I'm pretty much under control -- but on a day like today," Jackie Bien, allergy patient, said.
Those with bad allergies should stay indoors, keep windows closed and use the air-conditioning to purify the air and eliminate humidity. Allergy medicines and injections may also help, as can special mattress covers that protect against mold. Another tip- wash hair regularly.
Dr. Leija goes on the roof of the Gottlieb Professional Building every weekday morning during the allergy season -- March/April to October -- to gather pollen samples for the Midwest's official allergy count. You can follow @GottliebAllergy or visit Gottliebhospital.org. Gottlieb Memorial Hospital also has an Allergy Hotline at 1-866-4-POLLEN for English and 1-866-ALERGIA for Spanish.
Leija blames the continued heat, high humidity and weekend rain for causing the surge in mold spores.