Addressing indoor air quality in buildings can be a vexing problem for a number of reasons. These difficulties can be organized into the following general categories.
  1. Symptoms that are reported by building occupants are usually non-specific.
  2. No obvious source of exposure to environmental materials is readily observable to the health agent.
  3. Investigation of indoor air quality problems can require specialized knowledge concerning ventilation and heating systems; building maintenance and engineering; microbiology, toxicology; industrial hygiene practices and other areas outside the normal scope of activities of a board of health
  4. The BOH is frequently asked to investigate the conditions of the building after a substantial time has passed since the initial complaints from building occupants/the general public.
  5. Building occupants expect that the reported problems can be fixed instantly upon investigation, even when conditions in a building may result in substantial modifications to a building.
  6. There are no unified environmental statutes, regulations, or standards that may be consulted to readily to ascertain whether a building has an indoor air quality problem.
Each of these factors can place both the board and health agent in a difficult position to evaluate reported "sick building syndrome." In the experience of BEHA, indoor air quality problems generally fall into three general categories:
  1. Heating, ventilating, and air-conditioning (HVAC) operations;
  2. Indoor microbial growth indoors
  3. Indoor/outdoor sources of respiratory irritants/vapors/gases/particulates.

HVAC systems

The HVAC system in a building is usually designed at a minimum to provide heat during cold weather. The State Building Code requires buildings to meet certain minimal standards for ventilation prior to the issuance of a certificate of occupancy by the building inspector. These minimal standards can be used to ascertain whether the HVAC system in a building is functioning adequately. The Massachusetts Building Code requires a minimum ventilation rate (see Table 1 for examples by buildings) of fresh outside air unless each room has windows that open (780 CMR 1209.0; SBBRS, 1997; BOCA, 1993). Chapter II of the State Sanitary Code has a similar requirement in that a domicile must have windows that open to a minimum of 4 percent of the floor area or have mechanical ventilation capable of exhausting air (see Table 2) (105 CMR 410.280; MDPH; 1997).

Table 1: Required Mechanical Ventilation Aira in Frequently Encountered Building Spaces/Areas

Facility/Area TypeOutdoor air [cubic feet per minute(cfm) per occupant]
Dining rooms15
Office spaces20
School Training Shops20
Beauty salons25
Commercial dry cleaners30
Smoking lounges a60
Dark Room0.5 cfm per square foot of floor space
Swimming Pools (pool and deck area)0.5 cfm per square foot of floor space
Pet Shops1 cfm per square foot of floor space
Public Restrooms b75 cfm per water closet or urinal
a BOCA National Mechanical Code-1993
b exhaust ventilation required

Table 2: Mechanical Ventilation Rates for Residences Required Air Changes 105 CMR 410.280
Type of RoomRequired Air Changes per Hour by Mechanical
Exhaust Ventilation System
Habitable Room a2
Toilet Room5
Shower Room5

a Other than bath, toilet of shower rooms

The reasons why an HVAC system does not provide adequate fresh air or exhaust ventilation can be numerous. Components are often disabled to save on energy costs, poor placement of air diffusers, lack of preventative maintenance and/or blockage of vents by building occupants are but a few of the problems that are frequently identified by BEHA staff during assessments. An operable HVAC system is important for providing comfort for building occupants. All buildings normally accumulate dust, gases, vapors or other pollutants indoors. People produce water vapor, waste heat, carbon dioxide and shedding skin cells. The HVAC system can also serve the purpose to reduce pollutant concentrations in the indoor environment. By introducing fresh air into a fixed volume space (e.g., a room), the pollutants are diluted into a larger volume of air. Dilution means a decrease in air concentration, which would also decrease the dosage of pollutants to room occupants. With reduced exposure to pollutants, a reduction or elimination of symptoms in room occupants should occur. Frequently, the HVAC system will also have an exhaust vent, which physically removes pollutants from the room. The actions of dilution and removal by a properly functioning ventilation system will reduce exposure to environmental pollutants while creating airflow.

Identifying the components of the ventilation system in any building is key to understanding how indoor air quality can be negatively impacted. Unfortunately, HVAC system designs can vary widely depending on the purpose of the building (residential, commercial, or government), the age of the building, the components of the ventilation system and the HVAC design. Understanding each of these aspects of a building's HVAC system is essential in order to address possible sources of environmental pollutants that may be in a building.

Microbial Growth

A second general area that can have a pronounced negative impact on indoor air quality in a building is mold and other microbial growth. At a bare minimum the following conditions are necessary to support mold growth in an indoor environment:

  1. mold spores.
  2. nutrients necessary to support mold proliferation.
  3. adequate temperature.
  4. moisture.

Of these general conditions, moisture is the only condition that can be realistically controlled in the indoor environment to prevent mold growth. Chapter II of the State Sanitary Code has several sections that are related to the prevention of microbial growth in a building.

  1. Windows, doors and other structural elements must be rendered weathertight (105 CMR 410.501, MDPH; 1997)
  2. Rooms cannot be used for habitation that are subject to chronic dampness and have more than ½ of the floor to ceiling height below the average grade of the surrounding ground (105 CMR 410.402, MDPH; 1997).
  3. Requirements for a smooth, non-corrosive, non-absorbent waterproof covering for floors in toilets, showers, kitchens and pantries 105 410.504, MDPH, 1997).

Each of these sections of the State Sanitary Code provide examples of methods that can be used to prevent moisture accumulation in materials that support mold growth. These methods can be used and applied to any structure that is experiencing indoor mold growth. Identifying the materials colonized by mold and removing them, as well as, locating the source of moisture that is promoting mold growth are important first steps to reduce possible indoor air pollutants. Replacement of moldy materials without identification and repair of the source of moisture would be expected to eventually result in new mold growth on the replaced building component. Non-porous materials can be salvaged with the application of an appropriate antimicrobial agent (0.5% bleach solution) and subsequent cleaning with soap and water. Examples of non-porous materials are cement, tile, metal, stone, and some hard plastic surfaces. Porous materials, such as paper, cloth, cardboard, ceiling tiles, carpeting, insulation and other related materials are more difficult to remediate. The American Conference of Governmental Industrial Hygienists (ACGIH) recommends that porous materials be dried with fans and heating within 24 hours of becoming wet (ACGIH, 1989). If porous materials are not dried within this time frame, mold growth may occur. Once water-damaged, nonporous materials cannot be adequately cleaned to remove mold growth without extraordinary means that can be time consuming and expensive and they should be replaced.

Indoor/Outdoor Sources of Respiratory Irritants/Vapors/Gases/Particulates

This general category encompasses a large number of materials that can create indoor air quality complaints. Table 3 lists materials that can serve as sources of vapor, gases and/or particulate exposure which may produce acute symptoms that often quickly resolve after leaving a building. These materials if used without adequate ventilation, poor hygiene practices, poor storage or inadequate maintenance can result in a build up of air concentrations of constituents of these products. Identification, reduction of air levels or elimination of the source of these materials can serve to improve indoor air quality.

Table 3: Potential Sources of Indoor Air Pollutants

  • Building renovations
  • Vocational shops
  • art rooms
  • Pottery kilns
  • Custodial products
  • Pesticide applications
  • Vehicle exhaust
  • wood stove smoke
  • photocopier
  • Mimeograph machines
  • chemical storage
  • new furniture
  • Carpeting
  • lamination machines
  • school/clerical supplies
  • fuel oil vapors
  • sewer gas from dry traps
  • janitorial supplies
  • water heaters
  • air fresheners
  • dry cleaning solvents
  • nail application solvents
  • spray paint
  • spray on artificial snow
  • dry erase markers
  • dry erase board cleaners
  • chalkboards

The key to identifying indoor air quality problems in buildings is the recognition that usually poor indoor air quality is not the result of a single cause, but is usually a combination of conditions that interact to degrade a building's environment.

Local Board of Health Responsibilities

The BOH must ensure that homes meet the standards set forth in the State Sanitary Code Chapter II, 105 CMR 410.000, Minimum Standards of Fitness for Human Habitation. In commercial or public buildings, the BOH has the authority to investigate public nuisances M.G.L. c. 111 sec. 142.

Massachusetts Department of Public Health Responsibilities Concerning General Indoor Air Quality Issues

The MDPH has the statutory responsibility to "conduct sanitary investigations and investigations as to the cause of disease…and shall advise the government concerning the location and other sanitary conditions of any public institution" (MGL c. 111 sec. 5). To meet this responsibility with regard to indoor air quality, requests are referred to BEHA's Emergency Response/ Indoor Air Quality (ER/IAQ) unit for assessment. After a preliminary evaluation by the ER/IAQ staff, an assessment will be scheduled for the building of concern or a referral is made to the appropriate state agency. After the indoor air quality assessment is completed, a report with recommendations for remediating any problems identified and a letter of transmittal is sent to the BOH, state and local government officials and/or the party requesting the survey.

When IAQ assessments require further follow-up beyond the scope of the IAQ unit, other programs within BEHA may become involved in a building assessment. BEHA has a broad mission of protecting the public health from a variety of environmental exposures, including general indoor air quality, radon and asbestos. The BEHA responds to environmental health concerns and provides communities with epidemiological and toxicological health assessments.
BOH may contact BEHA to request technical assistance concerning indoor air quality complaints or to request an indoor air quality investigation of public buildings.

For more information, contact:
Emergency Response/Indoor Air Quality Program
Environmental Health
(617) 624-5757
CEH website address at

In some specific cases, statutes were enacted or regulations promulgated to regulate the following indoor air quality pollutants:

  1. Radon;
  2. Lead;
  3. Asbestos;
  4. Environmental (second-hand) tobacco smoke;
  5. Formaldehyde off-gassing from urea formaldehyde foam insulation (UFFI); and
  6. Carbon monoxide and nitrogen dioxide in indoor ice skating rinks.
    Regulations with regard to each of these pollutants require specific actions by the BOH and various state agencies.

Dated: 2/2001
References for General Indoor Air Quality

ACGIH. 1989. Guidelines for the Assessment of Bioaerosols in the Indoor Environment. American Conference of Governmental Industrial Hygienists, Cincinnati, OH.

BOCA. 1993. The BOCA National Mechanical Code-1993. 8th ed. Building Officials & Code Administrators International, Inc., Country Club Hills, IL. M-308.1

MDPH. 1997. Minimum Standards of Fitness for Human Habitation (State Sanitary Code, Chapter II). Code of Massachusetts Regulations. 105 CMR 410.000.

MGL c. 111 sec. 5. Powers and Duties of the Department [of Public Health].

MGL c. 111 sec. 122. Regulations Relative to Nuisances; Examinations.

SBBRS. 1997. Mechanical Ventilation. State Board of Building Regulations and Standards. Code of Massachusetts Regulations. 780 CMR 1209.0.

This information is provided by the Indoor Air Quality Program within the Department of Public Health.