Solutions After Conducting an Indoor Air Quality Investigation (Part 3)

Heating and air conditioning systems are sometimes complex and can require evaluation by outside contractors or specialists.  To eliminate many of the probable indoor air quality problems, however, there are three areas that can be easily addressed to some degree by building owners.  These are a) filtration of airborne particulate, b) removal of built-up contamination, and c) the control of microbial growth.

Solution 1: Filtration of Airborne Particulate

The proper use of air filtration is the most effective and economical method for controlling particulate contamination in indoor air systems.  There are a number of manufacturers who provide quality air filter products at reasonable prices.

1. Choosing the Correct Filters 

Quite often there are many types of filters that can perform the same function.  Listed below are some criteria, other than price, that should be considered when selecting the best filter for the application:

  • Concentration of people in areas being conditioned
  • Quality requirements of products being manufactured
  • Sensitivity of equipment and systems being protected
  • Fixed or variable air volume systems
  • Contamination in the air (type, size and quantity)
  • Pressure of air in the duct systems
  • Available space for air filters

2. Controlling the Air Flow

Once the proper filter type has been selected, the filters need to be installed properly so that all of the air in the system goes through the filters. By-pass air can occur due to the following reasons:

  • Improperly installed or sealed filter holding frames
  • Missing or improperly installed gaskets
  • Damaged or leaking duct systems
  • Improper fasteners to hold filters in place.
  • Incorrect filter size (vs. the filter holding frame size)
  • Damaged filters
  • Blown out filters due to excessive pressure

3. Maintaining the Correct Filter Change Frequency

The final factor for managing the filters is to establish and maintain the proper change frequency for each filter type.  An excellent method for knowing when to change air filters is to install a differential pressure measurement device across the filter bank such as a manometer or magnehelic gauge.  Factors other than pressure-drop that affect change frequency are moisture and seasonality.

Solution 2: Removal of Built-up Contamination

During the investigation, all accessible areas of the HVAC system need to be inspected for contamination. Build-up of dirt and dust in the duct systems, fan housings, coils and other areas in the HVAC systems is not desirable, but is very common. From a health perspective, the buildup of contamination in air systems is a potential threat, but if managed properly, is not necessarily an actual problem to the building occupants. If the air re-circulating in a closed system is filtered properly, the moisture within the system is managed, and if there is not much turbulence in the system, a contaminated air system may be “theoretically” safe for the building inhabitants.

Solution 3: Controlling Microbial Growth

To protect building occupants from the risk of disease caused by microbial growth, the building owner must prevent or control the growth process.  The following methods to control microbial growth may or may not be practical:

  1. Remove moisture needed for microbial growth: This is a practical method to control microbial growth. The IAQ investigation needs to be focused on identifying and controlling possible moisture sources.  Elimination of a moisture source can often eliminate microbial growth problems and protect the building owner from risk.
  2. Remove nutrients needed for microbial growth: Dirt and dust are excellent nutrients for microbial growth. Once air systems become contaminated, cleaning the nutrients to a level to prevent microbial growth is sometimes necessary and can become costly.  Managing the air filter systems is the most economical method for minimizing nutrients and can sometimes replace the need for contamination removal.
  3. Control the temperature: This is effective, but is often not possible. Room temperatures for offices and manufacturing environments are usually in the temperature growth range for mold and mildew.
  4. Control the presence of spores: This is not normally practical, as spores are naturally prolific and difficult to eliminate in most systems.
  5. Disinfect the air systems: The use of anti-microbial chemicals is controversial. There are only a few disinfectants approved by the EPA.  Disinfectants can easily become harmful contaminants.

If your facility needs professional assistance with its indoor air quality, contact Carolina Filters today! A professional representative is ready to help determine any issues and gain control of your IAQ. “Practical IAQ Solutions for Building Owners” written by Carolina Filters’ CEO, Coles Dwight, was referenced in this post. Learn about Causes for an Indoor Air Quality Investigations & How to Conduct an IAQ Investigation.

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