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Transplant Talk: Environmental Factors and Lung Health

Occupational and Environmental Lung Diseases (Indoor Air and Health)

Yuh-Chin T. Huang, MD, MHS, Professor of Medicine, Duke University Medical Center, Durham, NC


  • —Individuals spend a large fraction of their time indoors (up to 95%)
  • —Air conditioning is warmer climates and heater in colder climates
  • —Many sources of various airborne pollutants are present indoors
  • —Lower ventilation rates will lead to increased energy efficiency but also can lead to the accumulation of pollutants (including CO2)


  • Particulate matter (PM)
  • Carbon monoxide (CO)
  • Ozone
  • Environmental tobacco smoke (ETS)
  • Volatile organic compounds (VOCs)
  • Formaldehyde (engineered wood), paint, 4-phenylcyclohexene (carpet), flooring, phthalates (caulks and sealants)
  • Biological pollutants
  • Dust mites
  • Allergens (plants, animals)
  • Molds
  • Radon
  • Asbestos


  • Age: children, pregnant women, elderly
  • Preexisting medical conditions: allergy, asthma, COPD cardiopulmonary diseases, immunocompromised host
  • Individual sensitivity: genetic traits
  • Exposure levels
  • For long-term effects, there is considerable uncertainty about what concentrations or periods of exposure are necessary to produce specific health problems


  • Main sources: diesel engines in trucks, buses, and non-road vehicles (e.g., marine, construction, agricultural, and locomotive)
  • Indoor cooking/biomass burning
  • For outdoor air, EPA NAAQS annual limit: 15 µg/m3 ; 24-hour limit: 65 µg/m3
  • There are currently no federal government standards for PM2.5 in indoor air environments

Health Effects of Indoor PM

  • Exacerbations of existing respiratory diseases
  • Development of chronic lung diseases
    • Asthma
    • COPD
    • Lung cancer (diesel exhaust)
  • Cardiovascular mortality and morbidity
  • Increased susceptibility to respiratory infections
  • Systemic adverse effects


  • Indoor levels typically track the outdoor levels
  • Indoor sources
    • Laser printers, copying machine, air cleaners with electric or ion generators


  • Exacerbations of existing respiratory diseases
    • Asthma
    • COPD
  • Increased susceptibility to respiratory infections


  • Organic chemicals that have a high vapor pressure at room temperature
  • Sources including:
    • Paints, paint strippers, and other solvents
    • Wood preservatives
    • Aerosol sprays
    • Cleansers and disinfectants
    • Moth repellents and air fresheners
    • Stored fuels and automotive products
    • Hobby supplies
    • Dry-cleaned clothing
  • Levels of VOCs are in general 2 to 5 times higher indoors than outdoors
  • There are hundreds of VOCs
  • The only VOCs the federal government regulates (as a carcinogen)
  • OSHA (PEL of 0.75 ppm, and an action level of 0.5 ppm)
  • HUD (0.4 ppm for mobile homes)
  • Sources: Building materials, smoking, household products, and the use of un-vented, fuel-burning appliances (gas stoves or kerosene space heaters), pressed wood products made using adhesives that contain urea-formaldehyde resins
  • In developing countries: mosquito coils, solid fuel
  • During the 1970s, many homeowners had urea-formaldehyde foam insulation (UFFI) installed in the wall cavities of their homes for energy conservation
Health Effects of Formaldehyde
  • Watery eyes, burning sensations in the eyes and throat, nausea, and difficulty in breathing in some humans exposed at elevated levels (above 0.1 ppm)
  • High concentrations may trigger attacks in people with asthma
  • Some people can develop a sensitivity to formaldehyde
  • Cause cancer in animals and may cause cancer in humans


  • Ubiquitous to the environment
  • Thousands of known species of molds
  • Very tolerant to temperature and humidity extremes
  • When visible to the unaided eyes, molds have formed large colonies
  • Most are not pathogenic but can cause disease in immunocompromised hosts
Health Effects Associated With Molds
  • Allergy
  • Exacerbation of asthma
  • Upper respiratory tract symptoms (cough, wheezes) in normal individuals
  • Hypersensitivity pneumonitis: farmer’s lung, humidifier fever, compost lung, etc
  • Pneumonia (especially in immunocompromized hosts)
  • Sick building syndrome (?)


  • Perennial sinus congestion
  • Recurrent respiratory infections
  • Repeated positive respiratory cultures of environmental molds
  • Water stains/roof leaks/flooding


  • Source control
  • Improved ventilation
  • Air cleaners (air purifiers) with HEPA filters
    • Corsi-Rosenthal box
Source Control
  • Check gas stoves, and appliances regularly
  • Change vent filters regularly (HEPA filters)
  • Be vigilant about the presence of molds
  • Decrease mold exposure
    • Avoid compost piles, cut grass, and wooded areas.
    • Control moisture
    • Dehumidifiers, air conditioners
Improved Ventilation—
  • Opening windows and doors, operating window or attic fans, when the weather permits
    • Especially important for short-term activities that can generate high levels of pollutants — painting, paint stripping, heating with kerosene heaters, cooking, or engaging in maintenance and hobby activities such as welding, soldering, or sanding.
  • Window air conditioner
Air Cleaners (Air Purifiers)
  • —Many different models
  • —Effectiveness
    • —Look for a percentage efficiency rate and cubic feet per minute
  • —Not for removing gaseous pollutants

Indoor air pollutants can cause immediate and long-term health effects, especially in susceptible individuals. Remain vigilant about changes in the indoor environment and make necessary remediation as early as possible.

Protect Indoor Air Quality in Your Home

To learn more: https://www.epa.gov/indoor-air-quality-iaq/protect-indoor-air-quality-your-home


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