Farmer’s lung or Hypersensitivity pneumonitis

Farmer’s lung is a serious respiratory condition also known as hypersensitivity pneumonitis. It affects people whose immune system is sensitive to fungal spores inhaled from:

  • Mouldy hay
  • Straw
  • Grain
  • Compost

Farmer’s lung is different from farmer’s fever also known as (ODTS – Organic Dust Toxic Syndrome) because it involves an allergic immune response that leads to inflammation and permanent tissue damage in the terminal airways of the lung. Farms lung is associated with intense or repeated exposures to biologic dusts. IT was described as early as 1713. Some agricultural industries with possible known exposures associated with hypersensitivity pneumonitis include:

  • Greenhouse farming
  • Mushroom, farming
  • Bird or poultry handling (‘bird breeder/fancier’s lung’)
  • Grain processing (wheat weevil disease)
  • Hay packing, storing and handling particularly when humid

The symptoms of farmer’s lung can last from 12 hours to 10 days. Symptoms include:

  • Chills
  • Fever
  • Cough
  • Shortness of breath
  • Tight feeling in the chest
  • Tiredness

For those farmers who are sensitive, repeated exposure to the allergic trigger can lead to more severe symptoms such as chronic cough with phlegm containing pus, shortness of breath, loss of appetite and weight loss. Lung scarring (fibrosis) can occur in the later stages of the disease which greatly impacts respiratory health and cause difficulty breathing.

Farmer’s lung can be prevented by ensuring organic materials are kept dry and stored properly. Keep storage areas well ventilated and wear appropriate Australian Standard respiratory masks which seal the face properly. If working in greenhouse environs ensuring adequate ventilation and appropriate breaks out of the environment. These actions will minimise the risk of inhaling the allergic trigger and prevent the condition developing or progressing.

References used for this topic page

More information:

RACGP – Australian Family Physician
The respiratory tract

The National Center for Biotechnology Information
Pulmonary Health Effects of Agriculture (2016)

Canadian Centre for Occupational Health and Safety
Farmer’s lung

JAMA Network
An Outbreak of Organic Dust Toxic Syndrome in a College Fraternity

Cedars-Sinai (US)
Hypersensitivity pneumonitis

University of California
Hypersensitivity pneumonitis – signs and symptoms

Research & reviews:

National Center for Biotechnology Information
Systematic review of respiratory health among dairy workers.

European Respiratory Journal
Hypersensitivity pneumonitis – current concepts [PDF 132kb]

Radio graphics
Hypersensitivity pneumonitis: a historical, clinical and radiological review

Fast facts:

Farmer’s lung

  • Farmer’s lung is caused by inhaling fungal spores or bacteria from mouldy hay, grains, compost.
  • Farmer’s lung can be slowed if it is identified early. So tell your doctor about any symptoms like breathing problems, chills and fevers.
  • Keep hay, grains and other organic materials dry as fungal spores can only grow in moist conditions.
  • Wear PPE if working in at risk sites.

Last updated: 6th May, 2020