Field guide
Mold library
Airborne molds PollyMap partners identify in their weekly counts.
Summer–fall, peaks in late afternoon.
Alternaria
Alternaria alternata
Alternaria is one of the most clinically important outdoor molds, frequently triggering severe asthma attacks during late summer storms.
Year-round indoors and outdoors.
Aspergillus
Aspergillus spp.
Aspergillus spores are tiny enough to penetrate deep into the lungs. Beyond allergies, some species can cause invasive infection.
Year-round, peaks late summer.
Cladosporium
Cladosporium spp.
Cladosporium grows on living and dead plant material and is the dominant outdoor mold in most North American air samples.
Year-round, peaks indoors in fall and winter.
Penicillium
Penicillium spp.
Penicillium colonizes damp surfaces and stored food. Several species are common indoor allergens, especially in older or water-damaged homes.