Conventional homes and buildings create significant risks to health, greatly increase health related financial costs for individuals and businesses, and add a large burden to the health care system overall. Unfortunately, these risks and burdens are so common that they are routinely ignored. Now as interest is growing in zero energy homes and buildings as a way of reducing carbon emission, we have a unique opportunity to reduce the negative health impacts inherent in existing homes and businesses. In Part One of this three-part series, we discuss the associated health risks of conventional building practices. Part Two will describe how new zero energy building design and construction can solve this problem. And Part Three will present cost-effective approaches to addressing the risks in existing buildings while putting them on the path to zero.


The Risks of Outdoor Pollution

The risks of indoor air pollution are inextricably intertwined with outdoor pollution, which infiltrates and pollutes our indoor air. At the same time, toxic indoor air leaks out of, and is expelled from, our homes and buildings into the outdoor environment. It is currently a lose-lose proposition for our health and for the environment. Zero energy homes and buildings can play an important role in turning this situation around.

It is well known that outdoor air pollution puts our health at risk and represents a major cost to society. Outside air pollutants, especially ozone and particulate matter, as well as volatile organic compounds (VOCs), have been linked to increased rates of premature death, a variety of respiratory disorders including asthma (affecting 9% of children in the U.S.), wheezing, coughing and shortness of breath, developmental and reproductive issues, lung cancer, susceptibility to infection, and heart disease. It is also a risk factor for high blood pressure, diabetes, and attention disorders. Forty-one percent of people in the United States live in counties that have unhealthful levels of either ozone or particulate pollution – levels that may be “too dangerous to breathe.”

Even at low concentrations, air pollutants can affect our health. According to a study at the University of British Columbia, “Air pollution is the 4th highest risk factor for death globally and by far the leading environmental risk factor for disease.” A University of Chicago study has found that “fossil fuel-driven particulate air pollution cuts global average life expectancy by 1.8 years per person.” Another threat from outside the house is radon. This naturally-occurring, radioactive gas can seep into homes from the soil below. It is the largest cause of lung cancer in non-smokers and further increases the risk for lung cancer in smokers.


Sources of Outdoor Pollution

So where is all this outdoor pollution coming from? Burning fossil fuels is the main source of outdoor pollution, including car and truck exhaust, heating systems, and electric generating plants. Industrial emissions also result from solvents released by factories, and petroleum processing facilities. Forest fires and prescribed burns have also become a significant pollution source in recent years.

The issue is often exacerbated by geography (living in a valley, near highways or heavy industry, or in drought-prone forests in the West and Southeast). Temperature inversions, which keep pollutants close to the ground, and a warming planet, which increases ozone pollution, results in more frequent and larger wildfires, and longer and more intense pollen seasons. Another factor in the uptick in outdoor pollution is increased population density and urbanization. Urban residents have the worst exposures, although those living in rural areas can also be exposed, especially if living near areas of high traffic, agricultural pesticide use, industrial activity or wildfires. Indoor air pollutants from cleaners and personal care products that escape to the outdoors now almost equal fossil fuel emissions as a source of outdoor pollution.


Indoor Air Quality Worse for our Health than Outdoor Air

While outdoor air pollution is clearly a big problem, research clearly shows that indoor air pollution can be as bad or worse, often reaching harmful levels. The EPA found that indoor air may have two to five times (and in some cases 100 times) more pollutants than outdoor air. Other aspects of indoor air quality, such as high indoor humidity levels and widely fluctuating indoor temperatures, lead to poor health outcomes. Since the majority of us spend 90 percent of our lives indoors – at home, at work, in classrooms, in malls and other buildings – poor indoor air quality is even more of a health threat than outdoor air quality.


Six Causes of Toxic Indoor Air

There are six causes of poor indoor air quality.

  1. A leaky building or home allows outside air pollutants inside. The average home or building has nearly constant negative pressure resulting from the removal of air through bathroom fans and range hoods and replaces that air with potentially toxic outside air that leaks through the building envelope. Particulates and ozone from the air and radon from the soil can be drawn into the buildings. Drafts in older homes can also pick up and spread years of collected dust that contains pollen, dander, lead-paint, and asbestos.
  2. Materials commonly used or found in homes and buildings contain formaldehyde and volatile organic compounds (VOCs) that are given off as gases. Common sources of VOCs include: household products such as cleansers, disinfectants, aerosol sprays, air fresheners, moth repellents, printer ink, dry-cleaned clothes, and pesticides; construction materials such as floor and carpet adhesives, paints, insulation, varnish, carpets, cabinets, sealants, and composite wood products that are commonly used in construction; infiltration of outside air containing some of the outdoor pollutants mentioned above; and the occupants themselves, as humans and pets naturally emit some VOCs and other pollutants, shed pet dander or millions of human skin cells, and bring some pollutants inside on shoes, clothing and pets’ coats. Dust mites, tiny creatures that feed on skin cells that we slough off, are a common allergen also found in homes.
  3. Many homes have gas stoves, furnaces, and water heaters, as well as wood stoves, that release exhaust fumes into homes. These include carbon monoxide, carbon dioxide, formaldehyde, various oxides of nitrogen, and ultra fine particulates, the latter two of which may be associated with neurological development issues.
  4. Many homes and buildings are constructed in ways that trap moisture. An indoor relative humidity between 40 and 60% is optimal for human health, but daily we add gallons of moisture by breathing, flushing, cooking, washing clothes, and bathing, which can push relative humidity levels well above 60% and lead to mold, mildew, bacteria, pathogens, and viruses that thrive indoors. At relative humidity below 40 percent, viruses like influenza and measles flourish and our mucous membranes may dry up making us more susceptible to respiratory infections or irritation.
  5. Homes and buildings that have ducted heating systems can accumulate dust and mold and distribute it through the building, especially if filters are not changed regularly. Baseboard heating systems can also spread accumulated dust through convection currents.
  6. Most homes lack effective fresh air ventilation, filtration, and distribution systems designed in accordance with the basic tenants of building science. And many homes do not even meet ventilation standards required by current building codes.


Health Effects of Polluted Indoor Air

The resulting poor indoor air quality can trigger asthma as well as eye, nose, and throat irritation, headaches, exacerbated allergies, dizziness, nausea, and immune system impairment, along with the seemingly countless health problems caused by the outside air pollution mentioned above. Twenty percent of homes have one person with asthma and 20% to 40% of asthma attacks are linked to the home environment. Building dampness and mold alone are associated with an approximate 30% to 50% increase in a variety of respiratory and asthma-related health challenges. Poorly ventilated buildings result in significant reductions in human cognition compared to those with excellent indoor air quality. And they are associated with higher contagion concentrations, increased sick leave, and lower productivity in the workplace, significantly adding to the costs of doing business. Similar detrimental effects occur in homes and schools.


The health benefits of improved home energy efficiency and ventilation

Whether at home, in school, or at work everyone benefits from breathing fresh filtered, high quality air and avoiding the health and performance risks of breathing poor quality air.  Increased fresh air reduces illness, improves sleep, improves cognition, and improves productivity. In one study, cognitive functioning improved 100% on average in green buildings with enhanced ventilation compared to conventional buildings. In another study, low income residents with upgraded energy efficiency in their apartments saved hundreds of dollars per  year in health care costs, had 12% fewer asthma-related emergency room visits, a 48% decline in poor health, and a 23% reduction in poorly controlled asthma for children. Providing even minimally adequate ventilation in the work environment may reduce sick leave by about 40% – similar to the protection provided by a flu shot. Additionally, steady, comfortable indoor temperatures result in fewer cold and heat-related deaths, less hypertension, heart disease, asthma, and COPD.

There is a cost to society as a whole from both indoor and outdoor air pollution. Working or studying with poor quality air, reduces productivity and cognitive functioning of workers and students. The healthcare costs of pollution-related illnesses and their related emergency room visits tax our healthcare system greatly.


Zero Energy Buildings Create Healthy Environments

With proper design and construction, zero energy homes and buildings deliver superior health, functioning, and well being through improved indoor air quality, more natural daylight and enhanced peace of mind. In Part Two, we’ll explore the building materials and equipment needed to make these benefits a reality in newly constructed zero energy buildings. In Part Three, we will explore steps that can be taken to improve the indoor air quality in existing buildings. And we’ll show how they not only benefit the health and well being of building occupants, but also benefit the health of the greater community.


Don’t miss these great posts on indoor air quality:

Part Two: Zero Energy Buildings are Much Healthier Than Conventional Homes

Part Three: How To Improve Indoor Air Quality in Zero Energy Renovations