Identifying and managing indoor air quality issues
Gary A. Ganson, CIH, CSP, Certified Industrial Hygienist, and Rayne Chantel, CIE, Environmental Project Manager, Terracon, Lenexa, Kansas
Identifying an indoor air quality issue
Over the past two decades the public's awareness and understanding of the indoor environment has increased. In 1984 the World Health Organization committee report stated that up to 30 percent of new or remodeled buildings may have indoor air quality (IAQ) issues. Prior to this time, health and safety practitioners initially focused on health risks in the industrial environment. Since the focus began on the microenvironments created inside homes, schools, offices and other closed space where people congregate or work, identifying a health risk has become as much an art as it is a science.
The identification of what defines a health risk to building occupants might seem easy at a glance, but can pose a significant challenge to the investigator. Industrial hygienists and health professionals have been involved in the identification and control of health risks and have become entrenched in the work involved in uncovering the causative agents that are responsible for symptoms or illnesses presented in populations or single events from exposure inside buildings. A typical building investigation for IAQ issues includes interviewing occupants, inspecting the heating, ventilation and air-conditioning (HVAC) system, searching for possible pollutant pathways, and identifying possible contaminant sources.
The human body possesses two remarkable systems to protect us from the hazards of most airborne pollutants. The pulmonary system and our skin are two unique organs that have very sophisticated methods of providing a barrier and filtration system to eliminate or reduce the introduction of toxic substances from entering our bodies. While these systems work quite well, they can be either injured or overpowered by the constant bombardment or assault from highly hazardous materials. Symptoms and complaints from IAQ hazards, whether perceived or real, merit an investigation into their cause.
Over the past few decades there has been a constant improvement in the air quality of our industrial factories and environmental air quality. Most people today are aware that outdoor air pollution and indoor air quality can pose a risk to their health. The U.S. Environmental Protection Agency (EPA) studies of human exposure to indoor air pollutants indicate that many pollutants may be 25 to 100 times higher than outdoor levels.1 The reason there is increased concern is because typical workers spend as much as 90 percent of their time indoors.
|High-efficiency filter (HEPA) for clean air environment in a hospital|
Typical indoor air quality issues include fungi (molds), smoking, ventilation systems (temperature, humidity, carbon dioxide), chemicals, odors, radon gas, hazardous materials (asbestos and lead), off-gassing (building materials and office equipment) and applied materials (pesticides).
A major factor that increases poor indoor air quality is the poor operation of the HVAC system. Lack of proper ventilation may cause accumulation of particulates or volatile organic compounds (VOCs), and other gases such as formaldehyde, carbon monoxide, carbon dioxide or sulfur dioxide. Introducing cleaners, perfumes, and air fresheners will also increase the levels of VOCs which may cause irritation. The American Society of Heating, Refrigeration and Air-Conditioning Engineers (ASHRAE) provides guidance and recommendations for the proper operation of the HVAC system and environmental parameters for the building's supplied air quality.
The most widely publicized and controversial of agents fall into the group of fungi that make up 25 percent of earth's biomass. They can be subdivided somewhat into yeasts, mushrooms and molds. These groups of ubiquitous organisms exist everywhere in our environment and are an important part of our ecosystem. When molds are present in the indoor environment, they can produce symptoms in exposed individuals or populations that can present themselves as a serious health risk. Mold requires four things to be present for growth: spores, food, moisture and an activator. Typically, elimination of the moisture will prevent or limit mold growth. Some of the more common types of molds in the indoor environment include Aspergillus and Penicillium, Cladisporium, and Stachybotrys.
Managing indoor air quality
Once an investigation has identified the offensive agent(s) in the indoor environment, the next challenge is to effectively eliminate it, or control its introduction into the air space. This effort requires the building owner or the health and safety professional to apply effective measures that will remove the offensive agent, bioaerosol or modify the HVAC to improve the air quality and reduce the threat to the indoor environment.
There is a variety of means to accomplish this and the best is to start at the beginning. In new buildings, the Leadership in Energy and Environmental Design (LEED) has a green building rating system for building interiors and air quality in new construction. Using a defined set of parameters for the materials composition of building interior structures and systems, credits will be awarded for the resulting improvements in air quality. LEED certification requires that the building air achieve a very strict set of quality limits for contaminants such as carbon dioxide, formaldehyde, caprolactum (off-gassing from carpet), VOCs and particulate matter.
|High-efficiency clean room environment|
When the potential exists for mold growth because of moisture, elimination is the key to preventing amplification. If a water leak or water infiltration occurs, first fix the water problem, and then begin the drying-out process. Time is critical for fixing the problem. The New York State Indoor Air Quality guidance document states that wetted materials should be dried within 48 hours to prevent the growth of mold. Additionally, a rapid drying time will help decrease the humidity level in the building and thus decrease amplification of mold and fungi.
Managing the operation of the HVAC is critical to managing indoor air quality. This involves both area and room measurements for temperature, humidity and carbon dioxide. These parameters will provide important information to determine the adequacy of air exchanges, elimination of carbon dioxide and other gases, moisture control and maintaining a comfortable temperature. Maintaining proper moisture will also eliminate the potential for mold growth in ducts and on surfaces inside the building.
Equally important to building air quality is employee feedback. Symptoms unchecked or ignored can easily become a work-related health concern and result in decreased employee productivity. Substantiated hazards will also increase the potential for disease in exposed employees. It is important to listen and periodically poll workers to obtain important information regarding the building's air quality. The more attention placed on being a proactive building air quality manager will decrease missed and deceptive exposure problems that can become a larger problem to solve later.
Periodic inspections either by a trained professional or trained maintenance staff will also help eliminate future conditions leading to indoor air quality problems. These inspections conducted routinely include looking for visible signs of changing building conditions such as moisture that can lead to mold growth, HVAC filter blockage that reduces the delivery of conditioned air, dirty supply diffusers, building leaks that reduce HVAC efficiency or create cold drafts, and air diffusion for proper air exchanges, office equipment, break room appliances, air fresheners and installed building materials.
The best-managed buildings result from a focus on applying important IAQ tools. Inspection, proper maintenance, education and occupant communication are all critical elements to good building management and the elimination of IAQ problems. The cooperative effort of occupants, management and building maintenance provides a resource that collectively will prevent problems from surfacing and solve issues before they pose a threat to human health.
1 Targeting Indoor Air Pollution: EPA's Approach and Progress, U.S. Environmental Protection Agency, Office of Air and Radiation (6601), EPA Document #400-R-92-012, March 1993