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Who Is At Risk for Hypersensitivity Pneumonitis?

People who repeatedly breathe in foreign substances are at risk for hypersensitivity pneumonitis (HP). These substances, which also are known as antigens, include molds, dusts, and chemicals. However, most people who breathe in these substances don't develop HP.

People at increased risk include:

  • Farm and dairy cattle workers
  • People who use hot tubs often
  • People who are exposed to molds or dusts from humidifiers, heating systems, or wet carpeting
  • Bird fanciers (people who keep pet birds) and poultry handlers
  • Florists and landscapers, especially those who use liquid chemicals on lawns and gardens
  • People who work in grain and flour processing and loading
  • Lumber milling, construction, wood stripping, and paper and wallboard workers
  • People who make plastics or electronics, and those who paint or work with other chemicals
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Hypersensitivity Pneumonitis Clinical Trials

Clinical trials are research studies that explore whether a medical strategy, treatment, or device is safe and effective for humans. To find clinical trials that are currently underway for Hypersensitivity Pneumonitis, visit

May 09, 2014 Last Updated Icon

The NHLBI updates Health Topics articles on a biennial cycle based on a thorough review of research findings and new literature. The articles also are updated as needed if important new research is published. The date on each Health Topics article reflects when the content was originally posted or last revised.