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Extreme Weather Affects Indoor Air Quality

Climate Changes May Increase Health Problems Related to Indoor Air Quality, Report Finds

By Denise Mann
WebMD Health News

Reviewed by Laura J. Martin, MD

June 9, 2011 -- Heat waves, floods, and other extreme weather may affect indoor air quality and increase the risk of health problems, according to a new report issued by the Institute of Medicine.

"We spend 90% of our time indoors, and climate change and how we adapt and respond to it will have an impact on our health," says report author John D. Spengler, PhD, the Akira Yamaguchi Professor of Environmental Health and Human Habitation at Harvard School of Public Health in Boston.

Climate change, weatherization methods, and energy-efficient retrofits may be associated with indoor problems such as excessive temperatures and mold, causing dampness, poor ventilation, and emissions from building materials.

"People are experiencing intense heat outdoors, but vulnerable populations such as seniors are affected indoors because the buildings are under prolonged heat stress and the elements such as the walls get hot," Spengler says.

There is also an increased production of pollen with the higher temperatures, which affects indoor and outdoor air quality, he says.

What's more, brownouts and power failures caused by storms can negatively affect health. There are documented increases in carbon monoxide poisoning after storms because people buy portable electrical power generators that produce high levels of carbon monoxide. These generators should never be used indoors or in enclosed spaces, he says.

And "places also get wet that never got wet before, which leads to a cascade of mold growth and allergen production," he says. "Some of these places have not had rainfall like this ever or in a very long time and now the buildings are drying out and we see consequences, such as molds."

Energy-Wise, Health-Foolish?

Weatherization aims to seal air leaks in homes and buildings and insulate them to stop heat from escaping in an energy-efficient manner. But "we need more attention paid to the indoor air quality side, not just the energy rating," Spengler says.

Spengler is worried we are being energy-wise, but health-foolish. "We really understand and measure energy well, but we don't understand ventilation and health responses well," he says. "We have to be smart about how we go forward."

William W. Nazaroff, PhD, the Daniel Tellep Distinguished Professor of environmental engineering at the University of California at Berkeley, agrees. "Climate change will have consequences for public health, and a lot will be expressed through what happens in indoor environments," he says.

Not Easy Being Green

The biggest source of indoor air quality problems is central air conditioning, says Jeffrey May, principal scientist at May Indoor Air Investigations in Tyngsborough, Mass., and author of several books, including Jeff May's Healthy Home Tips. "With global warming, we use more air conditioning in most climates, and when you cool air, you reduce the temperature of the air and the humidity increases," he says.

"If you cool air, you get water," May says. "You have moisture in the coil of the air conditioner and if you don't have a good filtration system, the dust builds up, and wet dust turns into mold," he says.

An air conditioner is akin to a Petri dish in this sense, he says. Minimum efficiency reporting value (MERV) ratings are used to rate how well an air conditioning filter removes dust from the air as it passes through the filter. "Never have an air conditioner with anything less than MERV-8 rating or a MERV-11 if you have allergies," he says.

Such filters can be purchased at hardware stores and will prevent mold in a new air conditioning system and lessen it in an older system.

"One of the most important things people do to be green is to save energy," he says. Tightening buildings to make sure no air leaks from the outside makes buildings super-efficient and airtight, so you bring in fresh air through mechanical ventilation systems and blowers and the air gets filthy and moldy," he says.

"It's risky business being green," May says.

SOURCES: Institute of Medicine: "Climate Change, the Indoor Environment and Health."William W. Nazaroff, PhD, Daniel Tellep Distinguished Professor of Environmental Engineering, the University of California, Berkeley.John D. Spengler, PhD, the Akira Yamaguchi Professor of Environmental Health and Human Habitation, Harvard School of Public Health, Boston.Jeffrey May, principal scientist, May Indoor Air investigations, Tyngsborough, Mass.

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