Understanding and controlling common pollutants indoors can help reduce the risk of indoor health concerns for building occupants. Indoor pollutants and particulates are brought indoors by occupants, through ventilation system intakes or building openings, and from activities conducted within the building. Designing for effective indoor air quality (IAQ) can help produce a comfortable indoor environment for building occupants and prevent the human health problems associated with poor indoor air quality.
According to the EPA, all of us face a variety of risks to our health as we go about our day-to-day lives. Driving in cars, flying in planes, engaging in recreational activities and being exposed to environmental pollutants all pose varying degrees of risk. Some risks are simply unavoidable. Some we choose to accept because to do otherwise would restrict our ability to lead our lives the way we want. And some are risks we might decide to avoid if we had the opportunity to make informed choices. Indoor air pollution is one risk that you can do something about.
In the last several years, a growing body of scientific evidence has indicated that the air within buildings can be more seriously polluted than the outdoor air in even the largest and most industrialized cities. Other research indicates that people spend approximately 90 percent of their time indoors. For many people, the risks to health may be greater due to exposure to air pollution indoors than outdoors.
In addition, people who may be exposed to indoor air pollutants for the longest periods of time are often those most susceptible to the effects of indoor air pollution. There can be a serious risk from the cumulative effects of these sources. Such groups include the young, the elderly and the chronically ill, especially those suffering from respiratory or cardiovascular disease.
The likelihood of immediate reactions to indoor air pollutants depends on several factors. Age and preexisting medical conditions are two important influences. In other cases, whether a person reacts to a pollutant depends on individual sensitivity, which varies tremendously from person to person. Some people can become sensitized to biological pollutants after repeated exposures, and it appears that some people can become sensitized to chemical pollutants as well.
Indoor Air Pollution and Children
According to the National Environmental Education Foundation, children are at a higher risk for developing the negative health effects of indoor air pollution due to the amount of time they spend in school buildings. The schools present a heightened risk as they often suffer from poor IAQ due to old age and lack of funding to address indoor environmental issues, creating a nationwide challenge.
Children specifically are more susceptible to this risk as their bodies are still developing, and it is physically more difficult for children to process toxins as adults do. In addition, children are more sensitive to exposures, and they also experience greater exposures: they breathe, eat, and drink more relative to their size than adults do, and they play closer to the ground, exhibit more hand-to-mouth activity, and are less able to identify and protect themselves from potential hazards.
Children with asthma are at an even higher risk for negative health effects, including asthma exacerbation and asthma attacks, due to poor IAQ associated with environmental triggers. However, adults can also be negatively affected by poor IAQ and may even develop adult-onset asthma. Asthma-prone adults and children are both at risk for asthma symptoms or flare-ups due to environmental exposure to allergens such as dust mites, pests, pet dander, mold, and second hand smoke. Asthma symptoms in adults are often more persistent than they are in children. Adult-onset asthma, triggered by poor IAQ at schools, can affect teachers, school administrators, and other adults working in school buildings. Fortunately, design professionals can help make buildings safer for occupants and improve the indoor air quality.
The National Institute of Environmental Health Sciences has documented some of the most prevalent contaminants that affect indoor air quality. They include:
• Allergens are substances that can trigger the immune system, causing an allergic reaction; they can circulate in air and remain on carpets and furniture for months.
• Carbon monoxide is an odorless and toxic gas. It is found in fumes produced any time you burn fuel in cars or trucks, small engines, stoves, lanterns, grills, fireplaces, gas ranges, or furnaces. Proper venting or exhaust systems prevent build up in the air.
• Formaldehyde is a strong-smelling chemical found in some pressed wood furniture, wood particle cabinets, flooring, carpets, and fabrics. It can also be a component of some glues, adhesives, paints, and coating products. Formaldehyde is known to be a human carcinogen.
• Lead is a naturally occurring metal that has been used in a wide variety of products including gasoline, paint, plumbing pipes, ceramics, solders, batteries, and even cosmetics.
• Mold is a microorganism and type of fungus that thrives in damp places; different molds are found everywhere, indoors and outside.
• Pesticides are substances used to kill, repel, or control certain forms of plants or bugs that are considered to be pests.
• Radon is a colorless, odorless, naturally occurring gas that comes from the decay of radioactive elements in soils. It can enter indoor spaces through cracks or gaps in buildings. Most exposures occur inside homes, schools, and workplaces. EPA estimates radon is responsible for about 21,000 U.S. deaths from lung cancer annually.
• Smoke, a byproduct of combustion processes, such as from cigarettes, cookstoves, and wildfires, contains toxic chemicals like formaldehyde and lead.
LEED v4.1Enhanced Indoor Air Quality Strategies
The LEED v4.1 BD+C and ID+C Credit: Enhanced Indoor Air Quality Strategies is in the Indoor Environmental Quality (EQ) LEED category. The EQ category rewards decisions made by project teams about indoor air quality and thermal, visual, and acoustic comfort. Green buildings with good indoor environmental quality protect the health and comfort of building occupants. High-quality indoor environments also enhance productivity, decrease absenteeism, improve the building’s value, and reduce liability for building designers and owners. This category addresses the myriad design strategies and environmental factors—air quality, lighting quality, acoustic design, control over one’s surroundings—that influence the way people learn, work, and live.
The relationship between the indoor environment and the health and comfort of building occupants is complex and still not fully understood. Local customs and expectations, occupants’ activities, and the building’s site, design, and construction are just a few of the variables that make it difficult to quantify and measure the direct effect of a building on its occupants. Therefore, the LEED EQ section balances the need for prescriptive measures with more performance-oriented credit requirements. For example, source control is addressed first, in a prerequisite, and a later credit then specifies an indoor air quality assessment to measure the actual outcome of those strategies.
Professionals who want to learn more about indoor air quality can take the Stellar Design: Enhanced Indoor Air Quality Strategies course on the USGBC website.