The Monroe Township School District announced Monday night that it was closing all of its schools for at least a week because of possible mold infestation. A report from an environmental testing company showed that mold was detected on ceiling tiles, flooring, walls, lockers, desks, and toys at Holly Glen Elementary School.

We spoke with two Penn Medicine experts to learn more about the health concerns associated with mold exposure. Dr. James Palmer is chief of the division of rhinology, and Dr. John Bosso is director of the otorhinolaryngology allergy clinic.

How common is mold in the Philadelphia area? 

Palmer: You can get mold anywhere in the Philadelphia area, because we are a wet, humid area. Aspergillus is the No. 1 common mold we see.

Is mold harmful? 

Palmer: It is very much personal. It has to do with your body's own immune response to fungus. A small amount of fungus for one person can be trouble, while for another person it's no big deal. It is more about volume and exposure.

Bosso: If you're someone who is allergic to mold, you're going to be much more affected – you could experience asthma or sinusitis. High levels of mold can cause what we call "sick building syndrome" in those not allergic to mold – these people would experience headaches or nausea.

Are children at a higher risk of developing health problems from mold exposure?

Bosso: Not that we know of. Any age bracket can have problems with a mold infestation.

What are the common symptoms of mold exposure?

Palmer: Symptoms include shortness of breath, nasal obstruction, increased sneezing, and teary eyes. If I noticed those symptoms in my kids and I heard about these issues in the school, I'd take them to their pediatrician. Since these kids are missing a week of school, the big thing is going to be monitoring these symptoms during that time. If their symptoms are gone while they're out of school, that would concern me. Especially the wheezing symptom.

Is mold in a school building cause for concern?

Palmer: If I was a parent with a kid in that school, I wouldn't be overly alarmed. However, mold can be one of the triggers of asthma, a condition that is on the rise nationwide. If parents are seeing asthmatic-type symptoms in their kids — include runny or watery eyes, oozing, nasal obstruction — that are new since school started, I would get them looked at.

Why is asthma on the rise?

Palmer: It is not entirely clear, but probably the two main reasons are that we are breathing in more pollutants and also the so-called clean hypothesis. This hypothesis says that when kids were dirty and grew up with farm animals their immune systems, got used to irritants, but now kids are so clean that their bodies respond more easily to triggers.