|Spores from fungi (molds) range from 2 to 100 microns in diameter and contain many allergens which may worsen asthma and allergies. However fungi and fungal spores also produce many fragments smaller than 1 micron which contain allergens, beta-glucans, and fungal toxins (mycotoxins).|
Beta-glucans are carbohydrate-based molecules produced by molds which have immune-modifying properties and can worsen asthma and allergies.
Whole mold spores are big enough to be largely filtered out by the nose and throat before they enter deep in the lungs. However, particles smaller than 1 micron can readily enter deep in the lungs. These submicron particles are also small enough to travel easily through walls, floors, and ceilings.
Such small fungal fragments may increase risk for asthma. A South Korean study reported that average levels of airborne beta-glucans in submicron particles were 3 times as great (66.1 vs 23.0 picograms per cubic meter of air) in the homes of 15 asthmatic children as compared with homes of 14 non-asthmatic children. Homes with higher relative humidity had a significantly higher average level of airborne beta-glucans on submicron particles.
Fungal allergens, beta-glucans, and mycotoxins can all travel on particles smaller than a spore and smaller than 1 micron in diameter. A 2005 study reported that significant amounts of trichothecene mycotoxins were present on small (<1 micron) spore-free fungal fragments from Stachybotrys charatarum.
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