Ideally, the quality of air inside our households should be fresh, free of chemicals and other pollutants, and it should also maintain comfortable temperatures and humidity levels. However, a recent study conducted by a team of researchers from Washington State University said otherwise — there are high levels of pollutants, such as formaldehyde and probably mercury, in indoor air.
Furthermore, they also discovered that the levels of these pollutants vary throughout the day and increase with rising temperature. The study was led by Tom Jobson, a professor in the Department of Civil and Environmental Engineering, and a graduate student, Yibo Huangfu. It was published recently in the journal Building and Environment.
Air pollution is considered by the World Health Organization (WHO) as an “invisible killer” that lurks around us, affecting all age groups. Household air pollution, specifically, is known to be one of the leading causes of diseases and deaths in developing countries.
It is estimated that there were about 3.8 million deaths in 2016 that are attributed to exposure to smoke from cooking fires. It also accounts for 7.7% of the global mortality. This type of pollution dramatically impacts our health, resulting in adverse health conditions such as stroke, heart disease, lung cancer, and respiratory infections such as pneumonia.
Typically, we would automatically associate pollution with outdoor air and rarely with air inside our households. Unfortunately, indoor air is not as clean and fresh as we think it is. As what Jobson said, “people think of air pollution as an outdoor problem, but they fail to recognize that they’re exposing themselves to much higher emission rates inside their homes.” The issue should be taken seriously since, according to statistics, people spend about 90% of their time inside houses/buildings.
According to the WHO, there are a variety of pollutants suspended indoor like smoke, mold, building materials, home products, volatile organic compounds (VOCs), and naturally occurring gases. Smoke is the most frequently encountered and the most dangerous due to its fine particles and carbon monoxide content.
In the study, the team of researchers monitored several homes – which they perceive as representative of typical households in the United States. They discovered that the formaldehyde present in indoor air also increased in concentration as the temperature rises. And that’s between three and five parts per billion every time the temperature increased one degree Celsius.
“As a home gets hotter, there is a lot more formaldehyde in the home. The materials are hotter and they off-gas at higher rates,” Jobson said. It could be inferred that heat waves and changing regional climate may affect the quality of air inside houses/buildings.
Before this study, people assumed that the number of pollutants remained the same throughout the day. But, according to the findings of this study, the levels of pollution vary throughout the day. The contaminants were highest in amount during the afternoon, while it was at its lowest in the early morning.
Surprisingly, a house that was built in the early 1970s with gypsum wallboard found to emit high levels of formaldehyde and probably mercury after it was heated. The heating system of the house was radiant heating in the ceiling — one of the most popular heating systems back then. The gypsum that makes up the radiant heating system is alleged to be responsible for the high levels of formaldehyde since it is usually made from waste products of the coal industry.
To test their hypothesis, the researchers tried to obtain a piece, heated it up in the laboratory, and true enough, formaldehyde was detected in high levels – about 159 parts per billion. Although the substance is unregulated in the United States, the US Agency for Toxic Substances and Disease Registry under the Centers for Disease Control has set the safety threshold to only eight parts per billion. “Exposure to these chemicals impacts people’s ability to think and learn,” said Jobson. “It’s important for people to be more cognizant of the risk — opening a window is a good thing.”
In an article by The Seattle Times, a key measure to improve indoor air quality is through the use of an efficient ventilation system. Limiting the introduction of pollutants is the first important step in preserving and protecting the quality of air in your households, and this can be achieved by mechanical ventilation systems.
Green roofs – roofs that are planted with vegetation could also be another potential solution, especially for commercial buildings. Benefits of green roofs include reduced carbon dioxide levels, as well as, decreased stormwater runoff and urban heat.