Hypersensitivity Pneumonitis And Air Conditioning Systems: Advice For Facilities Managers

Employers in the United States have a legal responsibility to provide their employees with safe working conditions, and air quality is an important part of any workplace. It's important to remember that the average person spends ninety percent of his or her time indoors, so clean air at home or in the workplace is vital. Workplace air conditioning systems help control air quality, and poor maintenance can lead to health problems like hypersensitivity pneumonitis. Learn more about this condition, and what building facilities managers need to do to prevent problems.

How the condition affects the body

Hypersensitivity pneumonitis (or extrinsic allergic alveolitis) is an inflammatory condition that affects the air sacs and airways in the lungs. Inhaled allergens trigger a hypersensitive reaction that can lead to fever, cough, chills and shortness of breath. Over time, constant exposure to these allergens can cause acute or chronic lung disease.

Types of hypersensitivity pneumonitis

There are many allergens that can cause hypersensitivity pneumonitis, and a lot of these substances are common in the workplace. The condition has taken on many names, often describing the common types of allergen that cause the reaction.

Common variations of this disease include:

  • Bagassosis (where sugarcane causes the reaction)
  • Cheese washer's lung (brought on by particles of cheese mold)
  • Farmer's lung (which mold particles in hay can cause)
  • Miller's lung (from weevils in wheat flour)

Humidifier lung is a type of hypersensitivity pneumonitis that a humidifier or air conditioner can cause. Offices, factories, medical practices and all other businesses that use air conditioning systems are at risk of causing this problem.

How air conditioners cause hypersensitivity pneumonitis

Hypersensitivity pneumonitis occurs when air conditioning systems circulate dust containing tiny particles of an allergen. Modern air conditioners have advanced filtering and other devices to prevent contamination, but poor maintenance and cleaning can stop these systems working effectively. Even if a contaminant is outside the building, the design and layout of an air conditioning system can significantly increase the risk of pollution.

Common contamination problems in HVAC air conditioning systems include:

  • Dust or dirt in ducts
  • Microbiological growth in a drip pan or humidifier
  • Improper use of biocides, sealants and cleaning compounds
  • Improper venting
  • Refrigerant leaks

HVAC systems are generally constant volume or variable air volume systems. These systems each use different amounts of outdoor air, and, as such, they each present a different contamination risk. That aside, good quality design, installation and maintenance are imperative to avoid contamination in all HVAC systems.

Managing internal air quality

The United States Environmental Protection Agency publishes comprehensive advice to help building owners and facility managers manage internal air quality (IAQ). A critical tool for any building manager is an IAQ action plan, which includes eight key steps, and a 100-point checklist to help manage air quality in the workplace.

Regular, thorough HVAC system inspections are a crucial part of any IAQ action plan. Building facilities managers should document any changes to the system over time, particularly when an engineer adds, removes or replaces parts and equipment. Pay particular attention to parts exposed to water (such as drainage pans), as these present the highest risk of microbiological growth.

Refer closely to the manufacturer's documents, and consult an expert engineer as required. HVAC system designs vary considerably, and it's important to thoroughly inspect every part. For example, small exhaust fans often work independently from the main HVAC system, and many facilities managers overlook these parts during an inspection.

Preventing contamination

An effective IAQ action plan should carefully consider all the ways that contaminants can get into the system. Even if your HVAC system is functioning perfectly, allergens can still contaminate the system so effective source control is vital. This may include:

  • Removing or reducing the source
  • Sealing or covering the source
  • Modifying the environment in some way (such as adjusting the humidity)
  • Diluting the source with clean air
  • Isolating the source with changes in air pressure

In many cases, the capacity and power of the HVAC system will dictate which of these options is most suitable. Building owners and managers must carefully balance cost, time and practicality when choosing the right solution.

Hypersensitivity pneumonitis is a relatively common condition that can cause acute or long-term chronic symptoms. Building facilities managers have a vital role to play in the prevention of this disease, so it's important to understand the different preventive steps you need to take.