(Adapted from the EPA publication "Office Building Occupants Guide to Indoor Air Quality@ISBN 0-16-042729-0; Publication Number IAQ-0109)
Factors that Contribute to Indoor Air Quality
Indoor air quality is not a simple, easily defined concept like a desk or a leaky faucet. It is a constantly changing interaction of complex factors that affect the types, levels, and importance of pollutants in indoor environments. These factors include: sources of pollutants or odors; design, maintenance and operation of building ventilation systems; moisture and humidity; and occupant perceptions and susceptibilities. In addition, there are many other factors that affect comfort or perception of indoor air quality.
Controlling indoor air quality involves integrating three main strategies. First, manage the sources of pollutants either by removing them from the building or isolating them from people through physical barriers, air pressure relationships, or by controlling the timing of their use. Second, dilute pollutants and remove them from the building through ventilation. Third, use filtration to clean the air of pollutants.
Management of Pollutant Sources, Both Inside and Outside the Building
Pollutants can be generated by outdoor or indoor sources, including building maintenance activities, pest control, housekeeping, renovation or remodeling, new furnishings or finishes, and building occupant activities.
One important goal of an indoor air quality program is to minimize people's exposure to pollutants from these sources. Some of the key pollutant categories include:
- Biological contaminants. Excessive concentrations of bacteria, viruses, fungi (including molds), dust mite allergen, animal dander, and pollen may result from inadequate maintenance and housekeeping, water spills, inadequate humidity control, condensation, or may be brought into the building by occupants, infiltration, or ventilation air. Allergic responses to indoor biological pollutant exposures cause symptoms in allergic individuals and also play a key role in triggering asthma episodes for an estimated 15 million Americans.
- Chemical pollutants. Sources of chemical pollutants include tobacco smoke, emissions from products used in the building (i.e. office equipment; furniture, wall and floor coverings; and cleaning and consumer products), accidental spill of chemicals, and gases such as carbon monoxide and nitrogen dioxide, which are products of combustion.
- Particles. Particles are solid or liquid substances which are light enough to be suspended in the air, the largest of which may be visible in sunbeams streaming in a room. However, smaller particles that you cannot see are likely to be more harmful to health. Particles of dust, dirt, or other substances may be drawn into the building from outside and can also be produced by activities that occur in buildings, like sanding wood or drywall, printing, copying, operating equipment, and smoking.
Type of Pollutant
Many different factors influence how indoor air pollutants impact occupants. Some pollutants, like radon, are of concern because exposure to high levels of the pollutant over long periods of time increases risk of serious, life threatening illnesses, such as lung cancer. Other contaminants, such as carbon monoxide at very high levels, can cause death within minutes. Some pollutants can cause both short and long term health problems. Prolonged exposure to environmental tobacco smoke can cause lung cancer, and short term exposures can result in irritation and significant respiratory problems for some people, particularly young children.
People can react very differently when exposed to the same contaminants at similar concentrations. For example, some people can develop severe allergic reactions to biological contaminants to which other people will not react. Similarly, exposure to very low levels of chemicals may be irritating to some people but not others. For people with asthma and other pre-existing conditions, exposure to irritants like environmental tobacco smoke or gases or particles from various indoor sources may cause more severe reactions than the same exposure would in others.
Moisture and Humidity
It is important to control moisture and relative humidity in occupied spaces. The presence of moisture and dirt can cause molds and other biological contaminants to thrive. Relative humidity levels that are too high can contribute to the growth and spread of unhealthy biological pollutants, as can failure to dry water-damaged materials promptly (usually within 24 hours) or to properly maintain equipment with water reservoirs or drain pans (i.e. humidifiers, refrigerators, and ventilation equipment). Humidity levels that are too low, however, may contribute to irritated mucous membranes, dry eyes, and sinus discomfort.
Design, Maintenance, and Operation of Building Ventilation Systems
Maintaining good indoor air quality requires attention to the building's heating, ventilation, and air conditioning (HVAC) system; the design and layout of the space; and pollutant source management. HVAC systems include all of the equipment used to ventilate, heat, and cool the building; to move the air around the building (ductwork); and to filter and clean the air. These systems can have a significant impact on how pollutants are distributed and removed. HVAC systems can even act as sources of pollutants in some cases, such as when ventilation air filters become contaminated with dirt and/or moisture and when microbial growth results from stagnant water in drip pans or from uncontrolled moisture inside of air ducts. Because of the HVAC system's importance, good indoor air quality management includes attention to:
- Ventilation system design. The air delivery capacity of an HVAC system is based in part on the projected number of people and amount of equipment in a building. When areas in a building are used differently than their original purpose, the HVAC system may require modification to accommodate these changes. For example, if a storage area is converted into space occupied by people, the HVAC system may require alteration to deliver enough conditioned air to the space.
- Outside air supply. Adequate supply of outside air, typically delivered through the HVAC system, is necessary in any office environment to dilute pollutants that are released by equipment, building materials, furnishings, products, and people. Distribution of ventilation air to occupied spaces is essential for comfort.
- Outside air quality. When present, outdoor air pollutants such as carbon monoxide, pollen, and dust may affect indoor conditions when outside air is taken into the building's ventilation system. Properly installed and maintained filters can trap many of the particles in this outdoor supply air. Controlling gaseous or chemical pollutants may require more specialized filtration equipment.
- Space planning. The use and placement of furniture and equipment may affect the delivery of air to an occupied space. For instance, the placement of heat generating equipment, like a computer, directly under a HVAC control device such as a thermostat may cause the HVAC system to deliver too much cool air, because the thermostat senses that the area is too warm. Furniture or partitions that block supply or return air registers can affect IAQ as well and need to be positioned with attention to air flow.
- Equipment maintenance. Diligent maintenance of HVAC equipment is essential for the adequate delivery and quality of building air. All well-run buildings have preventive maintenance programs that help ensure the proper functioning of the HVAC systems.
- Controlling other pollutant pathways. Pollutants can spread throughout a building by moving through stairwells, elevator shafts, wall spaces, and utility chases. Special ventilation or other control measures may be needed for some sources.
Factors that Affect Occupant Comfort and Productivity
Besides the factors that directly impact the levels of pollutants to which people are exposed, a number of environmental and personal factors can affect how people perceive air quality. Some of these factors affect both the levels of pollutants and perceptions of air quality.
Temperature- too hot or too cold
Air velocity and movement- too drafty or stuffy
Heat or glare from sunlight
Glare from ceiling lights, especially on monitor screens
Stress in the workplace or home
Feelings about physical aspects of the workplace: location, work environment, availability of natural light, and the aesthetics of office design, such as color and style
Work space ergonomics, including height and location of computer, adjustability of keyboards and desk chairs
Noise and vibration levels
Selection, location, and use of office equipment
Ask your supervisor or office manager whom to talk with if you have a concern about any of these factors.
Indoor Air Quality is a Shared Responsibility
Some of the factors that contribute to poor indoor air quality may originate from inadequate HVAC design. Some may be solely in the control of the building management, such as maintenance of the HVAC system and the amount of outside air being mechanically brought into the building. Others are largely in control of building tenants and occupants, such as materials used in renovations and products and furnishings brought into or used in the building by occupants. Some, like cleanliness and general housekeeping of the building, require the cooperation of both the building management as well as of the individuals who work in the building. For these reasons, indoor air quality is a shared responsibility.
Good indoor air quality management practices can make a big difference. However, some factors, like reactions to indoor air contaminants among highly susceptible individuals, or the quality of the outside air, may not be within anyones immediate control. It is also important to remember that any building, no matter how well operated, may experience periods of unacceptable maintenance, or in some cases, the actions of the building occupants.
It is also important to keep in mind that many perceived indoor air quality problems are often comfort problems, such as temperature, humidity, or air movement in the space being too low or too high. In addition, many symptoms, such as headaches, can have causes that are not related to factors in the building.
The Good News...
Even though the factors that affect the quality of the indoor environment are numerous, the good news is that most indoor environmental problems can be prevented or corrected easily and inexpensively through the application of common sense and vigilance on the part of everyone in the building. Success depends on cooperative actions taken by building management and occupants to improve and maintain indoor air quality. By becoming knowledgeable about indoor air quality, tenants and occupants are in a good position to help building managers maintain a comfortable and healthy building environment. Work with management any time you:
Identify or suspect an indoor air problem
Need cleaning and maintenance service
Plan to install new office equipment
Plan for renovations and/or remodeling with a professional interior designer and/or an architect
Experience leaks, spills, or accidents
Things Everyone in the Building Can Do
All of the occupants of a building can have a great influence on indoor air quality. Everyday activities like heating food in a microwave and using a photocopier can generate odors and pollutants. By being aware of indoor air issues, occupants can help prevent problems. Here are some things you can do:
- Do not block air vents or grilles. Keep supply vents or return air grilles unblocked, so you won't unbalance the HVAC system or affect the ventilation of a neighboring office. Furniture, boxes, or other materials near supply vents or return air grilles may also affect air flow. Follow your office procedures to notify building management if your space is too hot, too cold, stuffy, or drafty.
- Comply with the office and building smoking policy. Smoking is not allowed in campus buildings or areas where smoke may reenter the building.
- Clean up all water spills promptly, water and maintain office plants properly and report water leaks right away. Water creates a hospitable environment for the growth of micro-organisms such as molds or fungi. Some of these microbes, if they become airborne, can cause heath problems.
- Dispose of garbage promptly and properly. Dispose of garbage in appropriate containers that are emptied daily to prevent odors and biological contamination.
- Store food properly. Food attracts pests. Some foods, if left unrefrigerated, can spoil and generate unpleasant odors. Never store perishable food products in your desk or on shelves. Refrigerators should be cleaned on a regular basis to prevent odors. Keep kitchens and dining areas clean and sanitize as necessary to prevent pests and maintain hygiene.
- Notify your building or facility manager immediately if you suspect an IAQ problem. This helps management determine the cause of the problem quickly so that a timely solution can be reached.
What the Office Manager/Tenant Can Do
In leased space, the office manager or other person responsible for office policies and/or relations with the property owner is often in a position to directly and significantly impact indoor air quality in the space. For some businesses, responsibility for dealing with air quality issues may involve more than one person. The office manager should follow the business' internal procedures in dealing with the building management. Some of the things this person can do to improve indoor air quality include:
- Maintain a good working relationship with building management on indoor environmental issues. Cooperative efforts are the best way to solve many indoor air quality problems. Follow your internal guidelines to ensure that building facility management is informed of, and involved in, all indoor air quality issues. Be as knowledgeable as possible when dealing with building management on indoor air issues.
- Place office furniture, partitions, and equipment with air circulation, temperature control, and pollutant removal functions of the HVAC system in mind. Make sure air supply vents and return grilles are not blocked by furniture or equipment. Computers and other heat-producing equipment placed near or under an HVAC sensor device system can trigger cooling, even if the actual temperature for occupants is cool. Place such equipment away from HVAC sensors to avoid this kind of situation.
- Coordinate with building management in instances when responsibility for design, operation, and maintenance of the HVAC system is shared. Sometimes the portion of the HVAC system servicing a lease space is the responsibility of the tenant. In such cases, work closely with building management to ensure that all parts of the building are receiving optimal services from the system. Ensure that filters in window air conditioners and perimeter heating and cooling units are changed frequently.
- Establish an effective smoking policy. Most of us today are aware of the health risks of smoking, not only to smokers, but to those who are exposed to secondhand smoke. In addition, environmental tobacco smoke in a building can increase costs for maintaining the ventilation system and for cleaning and replacing smoke-soiled furnishings and materials. Establish a smoke-free policy in the space under your control or work with the building management to design properly ventilated smoking rooms that do not allow smoke to circulate through the central ventilation system or to adjoining spaces.
- Avoid procedures and products that can cause problems. Many common products used in offices, like solvents, adhesives, cleaners, and pesticides, can give off pollutants and odors, as can office equipment such as copiers, printers, and fax machines. If any of these items are used in the office environment, adequate and sometimes separate ventilation should be provided. If your organization engages in activities that may generate pollutants, such as photographic or printing processes, exhaust ventilation will be especially important. Pollutants and odors (which may or may not indicate a health concern) generated in your space may not only bother those in the immediate area, but may enter the building ventilation system and cause problems for other tenants in other parts of the building.
- Integrate indoor air quality concerns into your purchasing decisions. Take steps to reduce exposures to contaminants from cleaning products, and from new furnishings and building materials, when odors and chemical emissions are usually highest. Ask the designers, suppliers, and manufacturers to provide information on chemical emissions from products and any potential associated respiratory hazards. While emissions information may not yet be available for many products, many product manufacturers are starting to do emissions testing. The more consumers request such information, the sooner it will become widely available.
- Work with the building owner or manager to ensure use of only necessary and appropriate pest control practices, and non-chemical methods where possible. Pesticides can contribute to poor indoor air quality and can cause serious health effects when used improperly. Unacceptable levels of pest activity and damage should be prevented by the most economical means and with the least possible hazard to people, property, and environment. For example, if roaches are a problem, seal their entry points and properly store and dispose of food as part of a long term control strategy. If a chemical pesticide is selected, it should be used in strict accordance with label directions. To reduce airborne exposure to pesticides, consider using baits to kill pests instead of spraying. Work with building management to select the most appropriate pesticide to achieve your purpose, and do not purchase or use more than needed.
- Work with building management and contractors before you conduct remodeling or renovation activities to identify ways of keeping exposure to pollutants to a minimum. Properly isolating the area to be remodeled or renovated from other spaces and the HVAC systems, and scheduling these activities for evenings and weekends if possible, can go a long way toward minimizing potential occupant problems. If the renovation work is contracted through you, ensure that the architect or interior designer and contractor are made aware, in advance, of the practices and procedures to be used during construction activities. If possible, try to arrange for plastic wrappings to be removed from partitions, carpet rolls, and other new material before they are brought into the space. Ask to have the materials aired out in a clean, dry location outside the building for a few days before installation. This can significantly reduce chemical emissions and odors inside the building.
- Encourage building management to obtain and use the joint EPA/NIOSH guidance document entitled: Building Air Quality: A Guide for Building Owners and Facility Managers. EPA and the National Institute for Occupational Safety and Health (NIOSH) have published comprehensive guidance for building owners and managers to help them prevent and solve indoor air quality problems. Ensuring that your building management is knowledgeable about and committed to management of indoor air quality issues is an essential first step in preventing and fixing indoor air problems.
What Building Facility Managers Can Do to Promote Good Indoor Air Quality
As an occupant of an office building, understanding the role of the building management in maintaining a healthy and comfortable indoor environment is an important step in understanding how you can fit into the picture.
Address any existing and potential indoor air quality problems.
Educate building staff about indoor quality management by:
- providing training opportunities
- establishing clear pollutant source management policies
Operate and maintain the building and ventilation system for good indoor air by:
- establishing or reinforcing standard operating and maintenance procedures
- responding quickly to leaks, floods, and other accidents that occur in buildings to prevent indoor air quality problems from developing
Manage potential pollutant sources such as:
- remodeling and renovation materials and furnishings
- housekeeping and pest control products
- exhaust gases from loading docks or garages
Communicate with tenants and occupants about their roles in maintaining good indoor air quality.
Establish clear procedures for responding to indoor air-related complaints.
Keep a record of reported health complaints to aid in solving indoor air-related problems. This will help improve the chances of correctly diagnosing and then fixing problems, especially if a pattern in complaints can be detected.
If You Think Your Building Has an Indoor Air Quality Problem...
If you or others at your office are experiencing health or comfort problems that you suspect may be caused by indoor pollution, you can:
Inform your supervisor of your concerns through your usual and proper channels.
Talk with your doctor or other health care provider, and reports problems to Environmental Safety and Health (5-2918).
Cooperate with management during any indoor air quality investigation to aid the sometimes difficult process of identifying and solving problems.
For More Information...
There are many sources of additional information on indoor air quality in offices, homes, and schools and what people can do to ensure that their indoor environment is a healthy one. To obtain a list of available publications, contact EPA's:
Indoor Air Quality Information Clearinghouse
P.O. Box 37133
Washington, DC 20013-7133
FAX 202 484-1510
Visit EPA's Indoor Air Quality Home Page on the World Wide Web:
Building Air Quality: A Guide for Building Owners and Facility Managers
is available from:
Superintendent of Documents
P.O. Box 371954
Pittsburgh, PA 15250-7954
Order #: S/N 055-000-00390-4; Price $24