Mold
What it is
Outdoor fungal spores in the air, in spores/m³ (spores per cubic meter of air), counted under a microscope by the counting station you chose in Settings. Alternaria and Cladosporium are the two kinds that matter for asthma.
How it affects breathing
- Evidence. Seen in emergency-room studies: every kind of fungal spore is linked to more asthma visits than any kind of pollen, and Alternaria is linked to near-fatal attacks. Spores are small enough to reach the lower airways.
- How likely. Only for the minority of people with asthma who are sensitized to mold, and an allergist’s skin or blood test settles who is. For them it is a late-summer and fall problem, worst on dry windy days and around leaf piles, compost and mowing.
- What helps. The same daily controller inhaler and antihistamine that work for pollen, staying away from raking and mowing, and an N95 mask for yard work, since spores are particles a mask catches.
How Breathing Index measures it
Your Breathing Index uses the highest of the station’s last three counts, since the effect builds over a few days. It counts station days rather than calendar days because a station counts on weekdays only, and a calendar window would come up empty every Monday.
Where the number comes from
A counting station: a hospital, health department or clinic that collects spores on a glass slide and counts them on weekday mornings. A count older than three days is shown as an estimate.