Related by context. Frequent words. (Click for all words.) 61 Dust mites 59 fungal spores 59 pollen 57 pollens 56 fungi 56 bacterial spores 56 pollen grains 56 Nitrogen oxides 56 mold spores 53 aerosol particles 53 airborne allergens 53 airborne particles 53 steam vents 53 terpenes 53 mold fungi 52 Hydrogen sulfide 52 ragweed pollen 52 respiratory irritant 52 animal dander 52 bacteria fungi 52 spores 52 pyrethrins 52 Poison ivy 52 mycelium 52 trigger allergic reactions 51 naturally occurring bacteria 51 Sulfur dioxide 51 soot particles 51 lichens 51 weed seeds 51 funguses 51 bagworms 51 insects 51 toxicants 51 mucilage 50 fluorocarbons 50 Diesel exhaust 50 urushiol 50 Allergens 50 corrosives 50 anaerobic bacteria 50 diatomaceous earth 50 pseudomonas 50 temperature inversions 50 pet dander 50 dust particles 50 Spores 50 indoor allergens 50 pine bark 50 unpleasant smell 50 leafhoppers 50 phosphine 50 airborne particulates 50 Enterococcus 49 Nematodes 49 dust mite 49 houseplants 49 Ultraviolet light 49 ultraviolet UV light 49 Stink bugs 49 lichen 49 Alternaria 49 allergens 49 pollutants 49 Particulates 48 spore 48 aromatic hydrocarbons 48 allergy triggers 48 leaf litter 48 particulates 48 aromatic herbs 48 Hydrogen peroxide 48 sphagnum moss 48 humid climates 48 microbial pathogens 48 woody plants 48 combustion gases 48 carbon tetrachloride 48 Essential oils 48 resinous 48 Cyanobacteria 48 microscopic particles 48 rotting vegetation 48 house dust mite 48 aerosols 48 herbaceous plants 48 microscopic algae 48 microscopic organisms 48 particles 47 particles emitted 47 Pungent 47 holly berries 47 bacteria 47 houseplant 47 Invasive plants 47 airborne pollutants 47 bacterial toxins 47 VOCs 47 nanobubbles 47 seed pods 47 mites