Indoor Air Quality in Commercial and Institutional Buildings
Indoor Air Quality (IAQ) is a major concern to businesses, schools, building managers, tenants, and workers because it can impact the health, comfort, well-being, and productivity of the building occupants. OSHA recognizes that poor IAQ can be hazardous to workers’ health and that it is in the best interest of everyone that building owners, managers, and employers take a proactive approach to address IAQ concerns.
IAQ has been identified by the EPA as one of the top five most urgent environmental risks to public health. The Centers for Disease Control and Prevention (CDC) estimates that the majority of YESAir IAQ Monitor.jpgAmericans spend approximately 90 percent of their time indoors. On average, office workers spend approximately 40 hours a week in office buildings.
These workers also study, eat, drink, and, in certain work settings, sleep in enclosed environments where make-up air (i.e., fresh air added to re-circulated air) may be compromised. For this reason, some experts believe that more people may suffer from the effects of indoor air pollution than from outdoor air pollution.
Each building has its own set of circumstances. Air quality may be determined by the site of the building, its original design, renovations, whether air handling systems have been maintained, occupant densities, activities conducted within the building, and the occupants’ satisfaction with their environment. IAQ problems can arise from a single source or any combination of factors. Inadequate IAQ may begin with poor building design or failure of the building enclosure or envelope (roof, facade, foundation, etc.).
Other issues may be associated with the location of the building and mixed uses of the building. Many common IAQ problems are associated with improperly operated and maintained heating, ventilating and air-conditioning (HVAC) systems, overcrowding, radon, moisture incursion and dampness, presence of outside air pollutants, and the presence of internally generated contaminants such as use of cleaning and disinfecting supplies and aerosol products, off-gassing from materials in the building, and use of mechanical equipment. Improper temperature and relative humidity conditions can also present problems, especially concerning comfort.
Many IAQ complaints are associated with flaws in building design and by inadequate routine preventive maintenance of building enclosures (envelopes), plumbing, and HVAC systems.
To resolve many IAQ problems, a preventive maintenance program should be established based on the system’s recommended maintenance schedule outlined by the architect or engineer, the manufacturer, or an HVAC professional. Regular preventive maintenance not only ensures that systems are operating properly, but also can result in cost savings, improved operating efficiency, and increased worker productivity. The U.S. Green Building Council (USGBC), among others, has demonstrated that IAQ issues can be readily and practically addressed when building systems are retrofitted for energy efficiency.
Symptoms related to poor Indoor Air Quality are varied depending on the type of contaminant. They can easily be mistaken for symptoms of other illnesses such as allergies, stress, colds, and influenza. The usual clue is that people feel ill while inside the building, and the symptoms go away shortly after leaving the building, or when away from the building for a period of time (such as on weekends or a vacation).
Health or symptom surveys, such as the one included in Appendix D, have been used to help ascertain the existence of IAQ problems.
Failure of building owners and operators to respond quickly and effectively to IAQ problems can lead to numerous adverse health consequences. Health effects from indoor air pollutants may be experienced soon after exposure or, possibly, years later. Symptoms may include irritation of the eyes, nose, and throat; headaches; dizziness; rashes; and muscle pain and fatigue. Diseases linked to poor IAQ include asthma and hypersensitivity pneumonitis.
The specific pollutant, the concentration of exposure, and the frequency and duration of exposure are all important factors in the type and severity of health effects resulting from poor Indoor Air Quality. Age and preexisting medical conditions such as asthma and allergies may also influence the severity of the effects. Long term effects due to indoor air pollutants may include respiratory diseases, heart disease, and cancer, all of which can be severely debilitating or fatal.
Research has linked building dampness with significant health effects. Numerous species of bacteria and fungi, in particular filamentous fungi (mold), can contribute significantly to indoor air Pollution. Whenever sufficient moisture is present within workplaces, these microbes can grow and affect the health of workers in several ways. Workers may develop respiratory symptoms, allergies, or asthma. Asthma, cough, wheezing, shortness of breath, sinus congestion, sneezing, nasal congestion, and sinusitis have all been associated with indoor dampness in numerous studies. Asthma is both caused by and worsened by dampness in buildings.
The most effective means to prevent or minimize adverse health effects is to determine the sources of persistent dampness in the workplace and eliminate them. More details on preventing mold-related problems can be found in the OSHA publication titled: “Preventing Mold-Related Problems in the Indoor Workplace”. Other environmental factors such as poor lighting, stress, noise, and thermal discomfort may cause or contribute to these health effects.
Sources of Indoor Air Pollutants
The relative importance of any single source depends on how much of a given pollutant it emits, how hazardous those emissions are, occupant proximity to the emission source, and the ability of the ventilation system (i.e., general or local) to remove the contaminant. In some cases, factors such as the age and maintenance history of the source are significant.
Sources of indoor air pollution may include:
Building Site or Location:
The location of a building can have implications for indoor pollutants.
Highways or busy thorough fares may be sources of particulates and other pollutants in nearby buildings. Buildings sited on land where there was prior industrial use or where there is a high water table may result in leaching of water or chemical pollutants into the building.
Design and construction flaws may contribute to indoor air pollution. Poor foundations, roofs, facades, and window and door openings may allow pollutant or water intrusion.
Outside air intakes placed near sources where pollutants are drawn back into the building (e.g., idling vehicles, products of combustion, waste containers, etc.) or where building exhaust reenters into the building can be a constant source of pollutants.
Buildings with multiple tenants may need an evaluation to ensure emissions from one tenant do not adversely affect another tenant.
Building Systems Design and Maintenance:
When the HVAC system is not functioning properly for any reason, the building is often placed under negative pressure. In such cases, there may be infiltration of outdoor pollutants such as particulates, vehicle exhaust, humid air, parking garage contaminants, etc.
Also, when spaces are redesigned or renovated, the HVAC system may not be updated to accommodate the changes. For example, one floor of a building that housed computer services may be renovated for offices. The HVAC system would need to be modified for office employee occupancy (i.e., modifying temperature, relative humidity, and air flow). Indoor Air Quality
: When painting and other renovations are being conducted, dust or other by-products of the construction materials are sources of pollutants that may circulate through a building. Isolation by barriers and increased ventilation to dilute and remove the contaminants are recommended.
Local Exhaust Ventilati
on: Kitchens, laboratories, maintenance shops, parking garages, beauty and nail salons, toilet rooms, trash rooms, soiled laundry rooms, locker rooms, copy rooms and other specialized areas may be a source of pollutants when they lack adequate local exhaust ventilation.
Disturbing thermal insulation or sprayed-on acoustical material, or the presence of wet or damp structural surfaces (e.g., walls, ceilings) or non-structural surfaces (e.g., carpets, shades), may contribute to indoor air pollution.
Cabinetry or furniture made of certain pressed-wood products may release pollutants into the indoor air.
Workers in areas in which pesticides, cleaning products, or personal-care products are being applied may be exposed to pollutants. Allowing cleaned carpets to dry without active ventilation may promote microbial growth.
Building occupants may be the source of indoor air pollutants; such pollutants include perfumes or colognes.
Common Pollutant Categories
Although there are numerous indoor air pollutants that can be spread through a building, they typically fall into three basic categories: biological, chemical, and particle.
Excessive concentrations of bacteria, viruses, fungi, dust mites, animal dander, and pollen may result from inadequate maintenance and housekeeping, water spills, inadequate humidity control, condensation, or water intrusion through leaks in the building envelope or flooding.
Sources of chemical pollutants (gases and vapors) include emissions from products used in the building (e.g., office equipment; furniture, wall and floor coverings; pesticides; and cleaning and consumer products), accidental spills of chemicals, products used during construction activities such as adhesives and paints, and gases such as carbon monoxide, formaldehyde, and nitrogen dioxide, which are products of combustion.
Particles are solid or liquid, non-biological, substances that are light enough to be suspended in the air. Dust, dirt, or other substances may be drawn into the building from outside. Particles can also be produced by activities that occur in buildings such as construction, sanding wood or drywall, printing, copying, and operating equipment.
Prevention and Control of IAQ Problems
IAQ Management Approach
Ideally, an employer should use a systematic approach when addressing air quality in the workplace.
The components of a systematic approach for addressing Indoor Air Quality are the same as those for an overall safety and health program approach, and include management commitment, training, employee involvement, hazard identification and control, and program audit. Management needs to be receptive to potential concerns and complaints, and to train workers on how to identify and report air quality concerns. If employees express concerns, prompt and effective assessment and corrective action is the responsibility of management.
It is recommended that building owners/managers develop and implement an IAQ management plan to address, prevent, and resolve IAQ problems in their specific buildings. The EPA’s report, IAQ Tools for Office Buildings provides a set of flexible and specific activities that can be useful to building owners/managers for developing such a plan. A key feature of the plan is the selection of an IAQ Coordinator. The role and functions of an IAQ Coordinator are described in Section 3 of the EPA’s report, IAQ Tools for Schools Action Kit (24).
Other critical features of the plan include establishing necessary IAQ policies, assessing the current status of IAQ in buildings through periodic inspections, maintaining appropriate logs and checklists, performing necessary repairs and upgrades, and implementing follow-up assessments or other needed actions. Employers who lease space should be familiar with the building management’s program and methods for mitigating or resolving indoor air quality problems.
It is especially important for employers to know who to contact in buildings where there is mixed use and pollutants are emanating from other sources in the building. Employers should negotiate leases that specify Indoor Air Quality performance criteria. For example, a lease should specify that the space be ventilated with outdoor air while occupied and at a rate described in ASHRAE 62.1 Ventilation for Acceptable Indoor Air Quality. An important management strategy is to foster a team approach for problem solving and consensus building. The IAQ Team should include, but not necessarily be limited to, building occupants, administrative staff, facility operators, custodians, building healthcare staff, contract service providers, and other interested parties.
Identification and Assessment
Methods used in an IAQ investigation may include identifying pollutant sources, evaluating the HVAC system performance, observing production processes and work practices, measuring contamination levels and employee exposures, providing medical testing or physical examinations, conducting employee interviews, and reviewing records of medical tests, job histories, and injuries and illnesses. The Appendices provide resources and checklists that building owners, managers, and occupants can use to investigate IAQ complaints, document walkthrough inspections, and correct IAQ problems.
To prevent IAQ problems effectively and efficiently, building managers should know and understand the history of the building (construction, uses, maintenance, etc.). If possible, owners and managers should maintain blueprints and construction documents, including information about any renovations of the building.
- Inspect and assess the building envelope, including the roof, walls, and foundation, and promptly respond to identified problems. Routinely check the building for water leaks, seals around doors and windows, and any visible damp or moist parts of the building. Clean and dry any damp or wet building materials and furnishings within 24 to 48 hours after detection to prevent the growth of mold.
- Ensure and validate that the building is maintained under a slight positive pressure (i.e., air comes out of the building when exterior doors are opened).
- Check whether the temperature and humidity are maintained in a recommended comfort range (temperature: 68 to 78 degrees and relative humidity: 30% to 60%).
- Ensure that routine maintenance of the HVAC system is being performed, including the performance of the system bringing outdoor air into the building. (1).
- Monitor carbon dioxide (CO2) levels. The carbon dioxide levels can be used as a rough indicator of the effectiveness of ventilation, and excessive population density (e.g., overcrowding).
- Ensure that good housekeeping practices are being applied.
- Ensure that routine preventive maintenance and upkeep of buildings is being performed. A preventive maintenance program provides the care to all building systems and components that keeps them operating at peak performance according to manufacturer’s specifications, and also allows for early detection of problems.
- Ensure that scheduled renovations are isolated from the building’s general dilution ventilation system when occupants are in the building.
There are three basic control methods for lowering concentrations of indoor air pollutants:
1. Source management
Source management includes removal, substitution, and enclosure of sources. It is the most effective control method when it can be applied practically.
For example, the U.S. Consumer Product Safety Commission recommends installing carpets that are low-volatile organic compound (VOC) emitters, and encourages consumers to ask retailers or installers about the carpet industry’s voluntary “green label” program for new carpets. According to the carpet industry, the green and white logo displayed on carpet samples informs the consumer that the specific manufacturer’s product has been tested by an independent laboratory and has met the criteria for very low emissions. The label, however, is not a guarantee that the carpet will not cause health problems. Another example is that the employer can set up temporary barriers or place the space under negative pressure relative to adjoining areas to contain the pollutants during construction activities.
a. Local exhaust
Local exhaust, such as a canopy hood, is very effective in removing point sources of pollutants before they can be dispersed into the building’s indoor air.
b. General dilution ventilation
General dilution ventilation systems, when properly designed, operated, and maintained, will control normal amounts of air pollutants. A well designed and functioning HVAC system controls temperature and relative humidity levels to provide thermal comfort, distributes adequate amounts of outdoor air to meet the ventilation needs of building occupants, and also dilutes and removes odors and other contaminants. Testing and rebalancing of HVAC systems are essential when partitions are moved in buildings. Appendix
C contains an HVAC System Maintenance Checklist that can be used to assist in routine maintenance of the HVAC system. For certain situations, such as painting and carpet cleaning, temporarily increasing ventilation can help dilute the concentration of vapors in the air.
Air cleaning primarily involves the removal of particles from the air as the air passes through the HVAC equipment. Most HVAC system filtration is provided to keep dirt off of coil surfaces to promote heat transfer efficiency.
Most smudging observed around air supply diffusers in a ceiling result from entrainment (trapping) of dirt particles in the space that accumulate there because of poor housekeeping.
a. Work Schedule
Through scheduling, managers can significantly reduce the amount of pollutant exposure in their buildings. For instance:
1. Eliminate or reduce the amount of time a worker is exposed to a pollutant (i.e., scheduling maintenance or cleaning work to be accomplished when other building occupants are not present).
2. Reduce the amount of chemicals being used by or near workers (i.e., limit the amount of chemicals being used by the worker during maintenance or cleaning activities).
3. Control the location of chemical use (i.e., perform maintenance work on moveable equipment in a maintenance shop as opposed to the general area, or locate the equipment (e.g., printers, copiers) in a separate room).
Education of building occupants regarding Indoor Air Quality is important. If occupants are provided with information about the sources and effects of pollutants under their control, and about the proper operation of the ventilation system, they can alert their employer and/or take action to reduce their personal exposure.
Housekeeping practices should include preventing dirt from entering the environment (using, for example, walk-off mat systems), removing dirt once it is in the building, disposing of garbage, storing food properly, and choosing cleaning products and methods that minimize the introduction of pollutants into the building.
Some indoor air problems can be resolved when good practices are put in place to control contaminants and building personnel follow good housekeeping approaches. Other problems may be difficult to resolve, however, and may require outside assistance. A building owner or manager may first want to consult local, state, or federal government agencies (e.g., education, health, environmental protection, or agriculture agencies) for assistance or direction in solving IAQ problems. These governmental agencies may be able to help an employer identify the types of experts who could best assist them.
Examples of experts include:
- Structural engineers – address issues with structural elements such as corrosion problems in a building’s foundation;
- Architects – responsible for designing the building envelope and can mitigate water intrusion problems by designing vapor barriers;
- Mechanical engineers – test and balance HVAC systems and may be able to assess and recommend repairs/replacement of HVAC systems and local exhaust ventilation systems; and• Industrial hygienists – assess general IAQ parameters such as air changes in a building, carbon dioxide levels, carbon monoxide levels, and other indoor pollutants, and also evaluate contaminant levels.There may be private firms or consultants in your area with experience in IAQ work. Such firms may be found in general resources such as a telephone directory (e.g., under “Engineers,” “Environmental and Ecological Services,” “Laboratories-Testing,” or “Industrial Hygiene Consultants”), on the Internet, or by asking building owners/managers for referrals.Some professionals who work with Indoor Air Quality issues must meet licensing and certification requirements to practice in their disciplines. A consultant should base any testing recommendations or protocol on a thorough visual inspection, walk around, and interviews with building occupants.
Source by: OSHA