Solving Indoor Air Quality Problems

There are many steps that can improve the quality of indoor air. Some of the most common measures are described below.

1. Remove or reduce the source of contaminants by:

• prohibiting smoking indoors or limiting smoking to areas that are under negative pressure and exhausted to the outside; 
  
  
• locating fresh air intakes away from polluted areas or exhaust vents; 
  
  
• installing local exhaust ventilation for machines and operations (photocopiers, printing equipment, laboratory procedures, etc.) that give off odors and contaminants; 
  
  
• steam cleaning carpets and partitions, and vacuuming again with a high-efficiency particulate air filter vacuum; and 
  
  
• properly storing all chemicals in an area with exhaust ventilation to the outside.

2. Increase ventilation rates.

The rate of air flow in a general office setting should, at a minimum, be 20 cubic feet of air per minute (cfm) per occupant. This recommendation comes from the American Society of Heating, Refrigerating and Air Conditioning Engineers (ASHRAE) standard 62-1989. The National Institute of Occupational Safety and Health (NIOSH) also recommends this as a minimum rate of air flow.

3. Maintain relative humidity between 30 and 60 percent.

In addition to providing comfort, humidity between 30 and 60 percent helps to control mold and mildew growth.

4. Clean and maintain the HVAC system regularly.

Maintenance of the HVAC systems includes cleaning and disinfecting duct work, supply diffusers and return vents. They should be cleaned, disinfected and open; make sure the fan is operating properly.

The Basics of an HVAC System

A properly designed and functioning HVAC system will provide a comfortable environment. The elements of the HVAC system include:

outdoor air intake 

mixed-air plenum and outdoor air control 

air filters 

heating and cooling coils 

humidification and/or dehumidification 

supply fans 

exhaust fans 

duct work 

cooling tower 

self-contained heating and cooling unit 

controls 

boiler 

water chiller

Guidelines for duct cleaning include:

• schedule duct cleaning when the building is not occupied to prevent exposure to chemicals and loosened particles; 
  
  
• keep the system under negative air pressure and drawing the air through a vacuum collection system; 
  
  
• use only HEPA (high-efficiency particle air) vacuuming equipment in occupied spaces; 
  
  
• avoid the use of sealants to cover interior duct work surfaces; 
  
  
• clean and sanitize coils and drip pans to reduce biological agents; and 
  
  
• remove or replace water-damaged porous materials in the duct work or other air handling system parts.

Indoor air quality standards

There is no OSHA standard for indoor air quality. OSHA does have standards to limit exposure to specific chemicals. However, it is very unusual when there is such a high level of one chemical that it is causing widespread problems and complaints.

Recommended standards for indoor air quality

The American Society of Heating, Refrigerating and Air Conditioning Engineers (ASHRAE) has issued recommendations for indoor air quality:

ASHRAE Standard 62-1989 — Ventilation for Acceptable Indoor Air Quality

ASHRAE Standard 55-1981 — Thermal Environmental Conditions for Human Occupancy

ASHRAE Standard 52-1976 — Methods of Testing Air-Cleaning Devices Used in General Ventilation for Removing Particulate Matter

 

See the following publications and websites for more information

AFSCME, Interior Air Quality, a Checklist for Identifying and Improving IAQ Problems

American Society of Heating, Refrigerating and Air Conditioning Engineers (ASHRAE)

Environmental Protection Agency, Building Air Quality

Environmental Protection Agency, Building Air Quality Action Plan

National Institute for Occupational Safety and Health, Guidance for Indoor Air Quality Investigations, 1987

National Air Duct Cleaners Association, 1528 K Street, N.W., Washington D.C. 20005, (202) 737-8847