Home air quality: What are you inhaling?
Particles and gases can be damaging to health, yet indoor air is not regulated.
Fri, Sep 03 2010 at 12:37 PM
In the early summer, my neighborhood experiences what we call the “yellow wind.” This onslaught is caused by thousands of acres of local pine forest releasing their pollen load in a few weeks’ time. It is not uncommon to see the edges of lakes yellow with accumulation. This accumulation also covers decks, cars and every horizontal surface in the house. We try to limit the deposits inside by closing the windows, but after nine months of winter, it is difficult to keep them closed when it’s finally nice outside.
In my previous career, I worked as an engineer/scientist for a biotechnology company. The facility I worked in was state-of-the-art and was used to manufacture pharmaceutical products. We had multiple levels of “clean rooms” in the plant and the air quality in many of these areas was typically 10 times cleaner than in a hospital operating room. Going to work in this extremely controlled environment during pollen season had my allergy-impacted eyes cleared well before lunch, and it was nice to have a few hours’ respite in my day.
These days, the clean rooms are just a memory and I work my way through the summer’s pollen with the aid of antihistamines. Pollen is just one contaminate that I now see regularly. As a carpenter, sawdust and other airborne particles are now more common. Most homeowners can add dust, mold and combustion byproducts to the list. Each of these items may have impacts on health and wellbeing for most people.
The Clean Air Act
In 1970, the Clean Air Act established the first set of National Ambient Air Quality Standards (NAAQS). The original goal was to monitor and provide regulations for a number of things that impact air quality: PM (particulate matter), ozone, sulfur oxides, nitrogen oxides, carbon monoxide and lead were items that saw initial controls. All of these items being monitored and regulated are considered outdoor contaminates; indoor air, by comparison, is virtually unregulated. Granted, it would be more difficult to have good indoor air if the outdoor air were extremely bad. But indoor air quality is often far worse than outdoor air.
John Spengler, a professor from Harvard’s School of Public Health, has done a lot of research on air quality. He states:
"Our studies, as well as others, reveal that people spend 65 percent of their time in their residences, 25 percent in some other indoor environment, 5-7 percent in transit, and usually less than 5 percent of their time is actually spent outdoors. The contaminant levels encountered in these indoor environments are important contributors to exposure, discomfort, irritation and health effects. Although we assess the effects of pollutants of outdoor origin (ozone, acidic particles, PCBs), we are particularly interested in pollutants of indoor origin (fungi, dust mites, nitrogen dioxide, tobacco smoke, lead, asbestos, volatile organic compounds, formaldehyde, radon and others). Concentrations of these pollutants can reach levels many times greater than outdoor levels. NO2 levels in hockey rinks can exceed 1 ppm, while homes with unvented gas cooking might vary between 20 and 100 ppb. In homes across North America, the presence of molds and mildew has been associated with substantial increases in upper and lower respiratory symptoms. Volatile components in gasoline can be 6 to 10 times higher inside a passenger car during rush hour traffic than values measured at standard urban monitoring sites."
Modern homes are air traps
Heating and cooling a home in an economical way has led to homes being built more airtight than ever before. While this is great from an energy use standpoint, the downside is poor ventilation and poor indoor air quality.
“It has long been known that airborne particles can contribute to lung and heart disease,” says Lynn Hildemann, Ph.D., an associate professor of civil and environmental engineering and a Clayman Institute faculty research fellow.
Hildemann says, “Vacuuming the carpet, making the bed, cooking dinner or using room freshener may be hazardous to one’s health. These activities all release potentially harmful allergens and pollutants. However, household air pollution is not regulated, putting respiratory health at risk. Indoor air pollution can be up to 10 times worse than outdoor air pollution because enclosed areas allow pollutants to accumulate. Regulation of pollutants has focused on outdoor air, even though people in developed countries spend most of their time indoors.”
Hildemann continues by saying:
"In our daily life we are exposed to a variety of air pollutants. We have a lot to learn about what they are, how much there are, to what extent they are harmful, and what we can do about it. Airborne pollutants fall into two categories: gases and particles. Outdoors, the kinds of gases we’re breathing (in addition to air) include carbon monoxide, nitrous oxides (called NOx), and ozone. Particle pollutants not only include natural sources like wind-blown dust, but also result from human activities, especially combustion emissions from car engines, furnaces, fireplaces, barbecues and cigarettes.
"The good news for our health is that regulation of car, power plant and industrial emissions over the last few decades have helped keep outdoor air much cleaner than it would be without those laws. But as population continues to increase, we have more cars, houses and energy demands than ever before. That means that even as we make everything cleaner, we could still see rises in overall pollution.
"The bigger issue, however, is the air you breathe indoors, because that’s where people, on average, spend about 90 percent of their time. Indoor spaces have unique kinds of air pollution, but there are virtually no regulations to limit them at all.
"The stuff we breathe indoors can be worse than outdoors for some pollutants, like vaporized chemicals, which come from paint and furniture (these are called 'volatile organic compounds' or VOCs), and biological particles, such as pet dander and molds. In some places, if you measure carefully, you can even find small amounts of other nasty things in the indoor dust, such as lead. We used to have lead in our gasoline and particles containing it settled next to roadways. People still track that in on their shoes, leave it on the floor and then kick it back up into the air later.
"Recently, my students and I have been studying indoor mold levels to determine how much of it comes in from outdoors versus how much gets kicked up indoors when people walk over carpets. By taking measurements in carpeted public spaces and homes, we’ve found a strong correlation between foot traffic and mold levels. We’ve shown the carpet to be a major source by comparing walking on carpeting with walking on a clean tarp. By having volunteers dressed in Tyvek suits walk around under the same conditions, we’ve been able to determine that people and their clothes are not a major source.
"One of the places we took measurements was in a hospital, where there are likely to be patients with poor immune systems and greater susceptibility to lung infections. If indeed further tests confirm that walking on carpets really kicks up molds into the indoor air, hospitals may want to rethink having carpets."
Indoor air quality is a worldwide issue
Hildemann recently took part in a study that looked at the effects of indoor air pollution on women in villages in southern Bangladesh. The women cook by burning debris and leaves indoors in crude, unvented clay stoves, creating dense buildups of smoke for several hours a day. Hildemann found that on a daily basis, the women breathed concentrations of airborne particles that were 15 times greater than the village men, who spend their time outdoors fishing. She also noted that respiratory illnesses among the very young were prevalent. “More young children die from respiratory illness there than from diarrheal diseases,” she says. “But parents do not associate these deaths with smoke exposure, even though the mothers keep their youngest children close by while they cook.”
Beyond the Third World
In the western world, we typically do not cook over open fires in small spaces, so most people are not exposed to this type of contamination. However, we have seen increases in asthma rates due to other issues, especially in urban children. A study by researchers at Johns Hopkins University found an association between increasing levels of indoor particulate matter pollution and the severity of asthma symptoms among children. The study, which followed a group of asthmatic children in Baltimore, Md., is among the first to examine the effects of indoor particulate matter pollution.
The study found:
"Particulate matter is an airborne mixture of solid particles and liquid droplets. The solid particles come in numerous shapes and sizes and may be composed of different chemical components. Fine particles measure 2.5 microns or less in size (approximately 1/30th the diameter of a human hair) and can penetrate deep into the body’s respiratory system. Coarse particles fall between 2.5 and 10 microns in diameter. These larger particles can also enter the respiratory system and can be produced indoors through activities such as cooking and dusting. The US Environmental Protection Agency (EPA) regulates outdoor levels of fine particle pollution, but does not have a standard for coarse particle pollution. There are no regulations for indoor pollution."
“We found that substantial increases in asthma symptoms were associated both with higher indoor concentrations of fine particles and with higher indoor concentrations of coarse particles,” said Meredith C. McCormack, MD, MHS, lead author of the study and an instructor with the Johns Hopkins School of Medicine.
In many cases, the level of indoor fine particle pollution measured was twice as high as the accepted standard for outdoor pollution established by the EPA.
“Children spend nearly 80 percent of their time indoors, which makes understanding the effects of indoor air very important,” said co-author Gregory B. Diette, MD, an associate professor in the School of Medicine and co-director of the Center for Childhood Asthma in the Urban Environment.
Education is key
I often laugh at some TV commercials that are attempting to brainwash the populace with ads selling air fresheners. They claim that by spraying their product about in your home you can actually “clean the air.” Never, in over a decade working as an engineer/scientist, have I seen the addition of an aerosol into a confined environment make the air cleaner or better. These scented products merely mask the smells that people assume are indicators of “dirty air.” In the pharmaceutical plant I worked in, we had very large air handlers that used banks of HEPA filters to remove particles and air contaminates. These were costly to install and maintain and far exceed anything that could or would be installed in a typical home. But only by removing contaminates can the air become “cleaner.”
Home filters and ionic systems
Many homes have forced air heating and cooling systems; the installation of better filters may reduce the concentrations of particles and other airborne contaminates that reside in everyone’s home. But these can never reach the efficiency of real clean rooms. The air exchange rates needed for true room-sized HEPA filtration would dwarf the capacity of most household furnace or A/C components. Many have managed limited reductions through the installation of filters or secondary systems, so their use has benefit. Just do not expect them to be the end-all solution. Ionic filters or particle collectors have limited scope as well, but also can generate ozone, which ironically is an outdoor contaminate that is regulated. These devices may reduce particle counts at the cost of added ozone in the home.
Integrated approach to better indoor air quality
Perhaps the best way to control indoor air is with a combined strategy. Limiting activities that produce particles and the removal of particle-harboring materials are great places to start. Limiting the use of aerosols and venting appliances that produce contaminates to the outdoors are also some great ideas for improving indoor air quality. Using low-VOC finishes and cleaners can reduce another category of contaminates commonly found in the home.
I have completed some remodel work over the years for clients with chemical sensitivities; replacing carpet with tile and using no-VOC paints were key areas to limit some types of exposure. These strategies reduced allergen and particulate levels. When cleaning is required, the use of vacuums that have high-efficiency filters is another way to ensure that particles are indeed collected and not just redistributed in the home. Behavioral changes can also provide for a cleaner home. I have noticed that when I close the windows in the early summer, at least on windy days, the pollen piles in my house are much smaller. The world is a dusty place, as are our homes. Some simple tips can keep most of it under control.
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