Is October “Mold Season” in Chicago?

Oct 12, 2017

“This is the time of year for mold around Chicago.” This isn’t a quote from an allergist, but rather Dusty Baker, the manager of the Washington Nationals (and past Cubs manager).  He made this statement at a press conference after game 4 of the NLDS baseball playoffs, which was postponed due to rain. This was in response to ace pitcher Stephen Strasburg feeling under the weather and declining to start game 4. This blog will examine Dusty Baker’s observation and let you know… is October mold season in Chicago?

There are many factors that influence the outdoor mold levels at any given time. The time of year, precipitation, wind speed and direction can all be factors. Seasonally, winter has the lowest levels of outdoor mold. With snow cover, we can even see outdoor levels at or very close to zero. In my experience, the highest levels that I see in the lab are during a wet spring period, and late summer. At these times we can see total outdoor counts over 10,000 spores per cubic meter of air.

Usually, by October, I start to see outdoor mold levels start to fall off towards their winter lows. This fall Chicago has been unseasonably warm, and over the past week, we have had rain off-and-on. Rain can cause higher levels of many common outdoor mold types such as basidiospores. The American Academy of Allergy, Asthma & Immunology’s National Allergy Bureau Pollen and Mold Report reported a “High” designation for the Chicago area on October 10, 2017. All of these factors are telling me that while it isn’t the common time for high mold levels in Chicago, we are seeing unseasonably high levels currently.

At the end of the day the mold didn’t seem to bother Stephen Strasburg and the Nationals too much, as they shutout the Cubs 5-0.