Sources of chemical pollutants come from five main categories: products used in the building, products that can get pulled into the HVAC system from outside the building, accidental spills, products used during construction activities, and byproducts of combustion such as carbon monoxide, formaldehyde, and nitrogen dioxide.

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Basics of Indoor Air Quality in the Workplace

The quality of indoor air in the workplace is important not only for workers' comfort, but also for their health. The Occupational Safety and Health Administration recognizes that poor indoor air quality (IAQ) can be hazardous to workers' health. Many factors affect IAQ—poor ventilation (not enough or lack of outside air), problems controlling temperature, high or low humidity, recent remodeling, and other activities in or near a building that can affect the fresh air coming into the building. Sometimes, specific contaminants—such as dust from construction or renovation, mold, cleaning supplies, pesticides, or other airborne chemicals (including small amounts of chemicals released as a gas over time)—may cause poor IAQ.

IAQ refers to the quality of air in non-industrial environments, such as offices. Since the energy crisis of the mid-1970s, indoor air quality has become an increasingly important issue for building owners, managers, and occupants. OSHA has identified the key attributes that typically lead to IAQ complaints as:

  • Improperly operated and maintained heating, ventilation and air-conditioning (HVAC) systems
  • Overcrowding
  • Radon
  • Moisture incursion and dampness
  • Presence of outside air pollutants
  • Presence of internally generated contaminates

Health Effects
Symptoms related to poor IAQ are varied, depending on the type of contaminant. They can easily be mistaken for symptoms of other illnesses. The usual clue is that people feel ill while inside the building, and the symptoms go away shortly after leaving the building.

Symptoms such as headaches, fatigue, trouble concentrating, and irritation of the eyes, nose, throat, and lungs are typical. Also, some diseases have been linked to specific air contaminants or indoor environments, such as asthma with damp indoor environments.

Whenever excessive moisture is present within the workplace, bacteria, mold, and fungi can grow and can lead to respiratory issues such as allergic reactions, asthma, coughing, wheezing, shortness of breath, sinus congestion, sneezing, nasal congestion, and sinusitis. Asthma is both caused by and worsened by dampness in the building.

OSHA suggests that a proactive approach be taken to address IAQ concerns.  Failure to respond expeditiously and effectively to IAQ concerns can quickly lead to more numerous or serious adverse health issues.

Common Pollutants
Typically these pollutants are present where water is found to support growth of bacteria, viruses, and fungi. Common biological pollutants can be dust mites, animal dander, legionella, and pollen. Inadequate maintenance and housekeeping of building ventilation systems can compound the issue.

Sources of chemical pollutants (gases and vapors) come from five main categories: products used in the building, products that can get pulled into the HVAC system from outside the building, accidental spills, products used during construction activities, and byproducts of combustion such as carbon monoxide, formaldehyde, and nitrogen dioxide. Some of the most common indoor air pollutants and means to control exposure are discussed in Appendix A of OSHA's "Indoor Air Quality in Commercial and Institutional Buildings." (OSHA document 3430-04)

These are described as a solid or liquid, non-biological that can be suspended in air, creating a respiratory hazard. This most often is dirt and dust drawn into the building ventilation system. Another source can be construction activities in the building resulting in suspended particles, such as drywall dust, wood dust, and silica from cutting, drilling, or sanding of concrete. Common particles and control measures are also described in Appendix A of OSHA document 3430-04.

Sources of Indoor Air Pollutants
There are many sources of air pollutants that contribute to IAQ problems. The importance of any one single source depends on several factors:

  • Quantity emitted
  • Toxicity of pollutant
  • Occupant proximity to the pollutant source
  • Ability of the building ventilation system to remove the pollutant

Sources of indoor air pollutants may include:

  • Building site or location
  • Building design
  • Building systems design and maintenance
  • Renovation activities
  • Local exhaust ventilation
  • Building construction materials
  • Building furnishings
  • Building maintenance
  • Occupant activities

Control of IAQ Problems
OSHA recognizes the "Three Lines of Defense" as a way of thinking about and applying specific actions to reduce or eliminate potential exposures to identified hazards. This is a commonly used and understood practice within the safety community. In this philosophy, you always apply the most effective method first, working down from there. This begins with eliminating/engineering the hazards out, then implementing administrative controls such as policies and procedures, and lastly, if the first two lines of defense are not feasible or are insufficient, incorporating the use of personal protective equipment (PPE).

Eliminating/Engineering Controls
Eliminating the source of the pollutant should always be the first option, and this starts with source management. This would include removal, substitution, and enclosure of pollutant sources. This is considered the most effective method when applied in a practical manner. For example, look for products such as paints and carpets labeled as “low VOC emitters” to help prevent IAQ issues at the source.

If the pollutant source cannot be eliminated, then engineering controls are the next step to control exposure. Examples include:

  • Local exhaust, such as a canopy hood, to remove point sources of pollutants before they can be dispersed into the building’s air circulation. Or an enclosure of a space under renovation with a negative air pressure blower to prevent leakage of pollutants into the general air circulation of the building.
  • General dilution ventilation, when properly designed and maintained, will control normal amounts of air pollutants. This controls temperature and relative humidity levels to provide thermal comfort, distributes adequate amounts of outdoor air to meet the needs of building occupants, and dilutes and removes odors and other pollutants before they become an issue. A specific example is Energy Recovery Ventilation (ERV). An ERV system has been proven to greatly increase the IAQ of a building. ERV is the process of exchanging the energy contained in indoor air that is normally exhausted and using it to treat or precondition the incoming outdoor ventilation air. During the warmer months, outside air coming in is pre-cooled and dehumidified, while in the cooler months, the outside air is humidified and pre-heated.
  • Air cleaning, which involves the removal of particles from the air passing through the filtration found in the general building ventilation system.  Filtration is done primarily to improve the heat transfer efficiency. 

Administrative Controls
If elimination/engineering controls prove to be infeasible, administrative controls should then be considered. Administrative controls fall into three general areas:

  • Work schedule: Exposure to indoor pollutants can be significantly reduced through scheduling by eliminating or reducing the amount of time a worker is exposed to a pollutant. This can be done by moving a task involving a pollutant to a time when it would minimally affect other employees in the area, by reducing the amount of chemicals being used by or near workers, and by controlling the location of chemical use to a designated area versus where employees normally work.
  • Training: By educating building occupants with information about the sources and effects of pollutants under their control, they will be more enabled to take action to reduce their personal exposure.
  • Housekeeping: Common practice is to prevent dirt and pollutants from entering the work space of the employee by use of matting, proper storing practices, and use of cleaning products.

Personal Protective Equipment
If elimination/engineering and administrative controls prove to be infeasible or insufficient, PPE should then be used to control exposure to indoor pollutants by use of respirators, gloves, protective clothing, eyewear, and footwear where necessary.

Applicable Standards and Regulations
OSHA does not have a formal IAQ standard but will enforce IAQ issues that pose a recognized hazard via the General Duty Clause Section 5(a)(1). OSHA also responds to questions about IAQ issues with letters of interpretation found in OSHA publication 3430-04 (2011) titled "Indoor Air Quality in Commercial and Institutional Buildings." This publication is a comprehensive guide provided by OSHA addressing IAQ issues.

National Consensus Standards
These standards provide guidance from their originating organizations.

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

  • 62.1-2016—Ventilation for acceptable indoor air quality. Specifies minimum ventilation rates and indoor air quality needed to avoid adverse health effects to human occupants.
  • 55-2013—Thermal environmental conditions for human occupancy. Specifies the combinations of indoor thermal environmental factors and personal factors that will produce thermal environmental conditions acceptable to a majority of the occupants.


  • E1971-05(2011)—Standard guide for stewardship for the cleaning of commercial and institutional buildings. The focus of this guide is to address appropriate cleaning activities and processes, to promote eco-efficiency and sustainability, and to avoid adverse impacts on the building occupants, cleaning personnel, the building structure itself, and the environment. 

Poor IAQ is a substantial problem that affects us all yet doesn't get the attention it deserves as a public health threat. It’s an issue that's been around for a while and is getting worse, especially as we construct increasingly air-tight, energy-efficient buildings. The good news is that poor IAQ is a problem that can be fixed following OSHA's three lines of defense philosophy. A variety of controls and actions can be taken to enhance interior breathing conditions and avoid the health issues generated from the presence of indoor air pollutants in our workplace.

This article originally appeared in the October 2016 issue of Occupational Health & Safety.

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