Plant allergens

Pollen grains, plant fragments

Vegetation, settled dust

Allergic conjunctivitis, rhinitis, sinusitis, asthma

Bacterial antigens

Cells, cell fragments

Growth in water or on organic matter, settled dust

Hypersensitivity pneumonitis

Fungal allergens

Spores, cell fragments

Growth in water or on organic matter, settled dust

Allergic conjunctivitis, rhinitis, sinusitis, asthma

Arthropod allergens

Dust mite or cockroach excreta and body fragments

Settled dust

Allergic conjunctivitis, rhinitis, sinusitis, asthma

Mammalian allergens

Particles of cat, dog, or rodent skin, saliva, or urine

Pets, pests, settled dust

Allergic conjunctivitis, rhinitis, sinusitis, asthma

Bacterial endotoxin

Gram-negative bacterial cells and cell fragments

Growth in water or on organic matter, settled dust

Humidifier fever, respiratory inflammation

Fungal toxins

Spores, cell fragments

Growth on organic matter

Toxic and irritant effects

Microbial volatile compounds

Gases and vapors

Bacterial or fungal growth on organic matter

Irritant and nuisance effects (e.g., unpleasant or annoying odors)

Carbon dioxide, body effluents

Gases and vapors

Human breath, body odor

Perception of insufficient fresh air, irritant and nuisance effects

Infectious viruses

Droplets, droplet nuclei of sputum, saliva, nasal or throat secretions

Infected or colonized persons

Acute viral respiratory disease, influenza, varicella (chickenpox), measles