| Environmental source | Major causative antigen |
| Byssinosis ("brown lung") (unclear if a true cause of HP; asthma is common) | Cotton mill dust (carding and spinning areas of cotton, flax, and soft-hemp) |
| "Velvet" worker's lung | Unknown (? nylon velvet fiber, tannic acid, potato starch) |
| Upholstery fabric (nylon filament, cotton/polyester, and latex adhesive) | Aflatoxin-producing fungus, Fusarium sp |
