Clean air laws were first enacted in the 1950s. Outdoor air quality has improved as a result. In the 1970s, indoor air quality became an important public health issue. This occurred through a series of events. These include:
IAQ is important because people spend a large portion of time in their homes. Studies show that people spend more than 90 per cent of their time indoors (at home, work and in transit). Of this time indoors, 65 to 70 per cent is at home.
There are many causes of air pollution. One type is called volatile organic compounds (VOC). These occur at much higher levels inside than out. A large U.S. study showed that indoor VOC levels were two to 10 times higher than those outdoors. Some activities done in the home caused indoor VOC levels to be 1,000 times higher.
Motor vehicles and industry are responsible for most of the outdoor air pollution. However, they are only linked to a small portion of indoor air pollution. Most people’s exposure is a result of the combination of high indoor VOC levels and so much time spent indoors. As an example, the chart shows exposure to benzene, which is known to cause cancer.
The chart shows that 97 per cent of benzene comes from motor vehicles and industries. However, they are only responsible for one-quarter of a smoker’s exposure to benzene, and one-half of a nonsmoker’s exposure. In comparison, the home, personal activities, and smoking are responsible for three per cent of benzene produced, but result in three-quarters of a smoker’s exposure, and one-half of a nonsmoker’s exposure. So although most of the benzene is produced outdoors, most of human exposure is from indoor air.
Air is a mixture of many chemical and biological agents. These interact with each other and with indoor and outdoor factors. They may be in the environment naturally, or result from a man-made activity. They include carbon monoxide, VOCs, solid particles, moulds or fungi and bacteria. There may be different chemical sources, including smoking, painting, petroleum, home renovations and home redecorating.
The biological sources include indoor growth of fungus as a result of water leaking or excess condensation within your home. All homes have indoor sources of air pollutants. The key is to keep them at safe levels.
In 1989, the U.S. Environmental Protection Agency reported that indoor air pollution is a high human health risk. It is one of the greatest threats to health of all environmental problems. There are many illnesses that are connected to, or made worse by, air pollution. These include eye, nose and throat irritation, nervous system poisoning, over-sensitivity to chemicals, and cancer.
Some people have more frequent and greater reactions to air pollution. These include children, the elderly, those with asthma or allergies, and people with lung problems. The way air pollution affects a person’s health depends on four things: how much a person is exposed to, the length of exposure, how poisonous it is, and how sensitive the person is to the pollution.
The urea formaldehyde foam insulation (UFFI) incident alerted people to what is known as ‘tight building syndrome’, ‘building related illness’, ‘environmentally induced illness’ or ‘sick building syndrome’. The condition was the result of the sudden wide use of UFFI in homes. This illness produced headaches, nausea, poor concentration, dizziness, lack of energy, uneven heart beat, flushing, laryngitis, irritability, depression, joint pain and extreme weakness.
Environment Canada - www.ec.gc.ca
U.S. Environmental Protection Agency www.epa.gov/iaq/
World Health Organization - www.who.dk/
Over time it was realized that some people were very sensitive to formaldehyde. Since the UFFI period, a large number of VOCs have been shown to cause sensitivity reactions. People vary widely in how they react to chemicals. Different people with the same exposure can be very ill or completely unaffected.
It is important to be aware of the impact of indoor air quality on our health. There are many ways each of us can improve the air quality in our home. We can make different lifestyle choices, maintain our homes well, and make interior decoration and home design changes. Here are some simple things that will keep the air we breathe at home safer.