What is hypersensitivity pneumonitis?
The term hypersensitivity pneumonitis (also known as extrinsic allergic alveolitis) refers to a group of lung diseases in which your lungs become inflamed as an allergic reaction resulting from exposure to dusts of animal and vegetable origin. Although complicated, the name “extrinsic allergic alveolitis” describes the origin and nature of these diseases.
- context "extrinsic"-- cause originating outside the body
- context "allergic"-- caused by the allergic reaction of the body to a specific substance or condition
- context "alveolitis"-- an inflammation in the inner part of the lungs (alveoli are the small air sacs in the lungs)
What are the occupations at risk?
Hypersensitivity pneumonitis occurs in many diverse occupations.
The following table lists several examples and the related occupations. Note that this list is not a full list of all occupations at risk.
- context Disease | Exposure | Preventive Maintenance
- context Air conditioner/humidifier lung | Humidifier water | Maintenance of air and water handling systems.
- context Animal handlers' lung | Dust of dander, hair particles, dried urine of rats | Good exhaust ventilation.
- context Bagassosis | Mouldy sugar cane | Application of propionic acid to bagasse. Good exhaust ventilation. Keeping moisture content above 20%. Enclosure of processes.
- context Bird fanciers' lung | Proteins in droppings and feathers | Good exhaust ventilation. Water spraying of droppings while cleaning.
- context Cheese washers' lung | Cheese mould | Wrapping the cheese in foil during aging.
- context Farmers' lung | Mouldy hay, straw, grain | See the prevention section below for dust control.
- context Hot tub lung | Bacteria in mist from hot tub | Maintain disinfectant level for water. Regular hot tub cleaning. Good exhaust ventilation.
- context Maltworkers' lung | Mouldy malt | Application of mechanical methods in the malting process.
- context Maple bark strippers' disease | Mouldy maple bark | Spraying of logs during debarking. Remote control of some operations.
- context Mushroom workers' lung | Mouldy mushroom compost | Good exhaust ventilation.
- context Sequoiosis | Mouldy sawdust | Good exhaust ventilation. Enclosure of processes.
- context Sewage sludge disease | Dust of heat-treated sludge | Good exhaust ventilation. At outside facilities, stand upwind of storage piles.
- context Wheat weevil lung / Miller’s lung | Mouldy grain, flour, dust | See the prevention section below for dust control.
- context Suberosis | Mouldy cork dust | Good exhaust ventilation.
- context Wood pulp workers' disease | Mouldy wood chips | Good exhaust ventilation. Remote control of some operations.
How can we help prevent hypersensitivity pneumonitis?
The ways to reduce dust exposure (dust control) include using the hierarchy of controls - engineering controls, administrative controls, and personal protective equipment.
Methods of engineering control include local exhaust ventilation, general ventilation, process enclosure and process isolation (separating the worker from the dusty process).
On farms, prevention of particle release and control of dust cloud formation are achieved by well-designed, leakproof ducting, and enclosed conveyor systems for grains and feeds. Buildings should have local ventilation systems in areas frequented by workers engaged in egg handling and feed storage and preparation. Within enclosed livestock units, temperature and relative humidity should be monitored. Adequate ventilation and sufficient fresh, replacement air should be provided. For field operations, tractors or combine harvesters with enclosed cabs that provide filtered air should be used.
Administration controls include education and training programs that emphasize the significance of animal and vegetable dust in causing diseases. Managers and workers should learn about methods of storing materials to prevent mould formation and reduce dust. In addition, develop and implement maintenance programs to, for example, keep humidifiers, hot tubs, and heating and cooling systems in good condition.
Personal protective equipment should be considered as the last resort for respiratory protection. Personal protective equipment should not be a substitute for proper dust control. Respirators, including dust masks, should only be used:
If respiratory protective equipment is needed for the job, then a full respiratory program should be put in place that includes selection, use, and care of respirators plus training and education for the worker. Because respirators provide different levels of protection, it is very important to assess the airborne contaminant before selecting the specific type of respirator.
- requirement when engineering or administrative controls are not technically feasible,
- requirement when engineering controls are being installed or repaired, or
- requirement when emergencies or other temporary situations arise (e.g., maintenance operations).