Formaldehyde is contained in urea-formaldehyde UF foam insulation installed in the wall cavities of homes as an energy conservation measure. Levels of formaldehyde increase soon after installation of this product, but these levels decline with time. The courts overturned the ban; however, the publicity has decreased the use of this product. More recently, the most significant source of formaldehyde in homes has been pressed wood products made using adhesives that contain UF resins [ 41 ].
The most significant of these is medium-density fiberboard, which contains a higher resin-to-wood ratio than any other UF pressed wood product.
Solutions to air pollution
This product is generally recognized as being the highest formaldehyde-emitting pressed wood product. Additional pressed wood products are produced using phenol-formaldehyde resin. The latter type of resin generally emits formaldehyde at a considerably slower rate than those containing UF resin. The emission rate for both resins will change over time and will be influenced by high indoor temperatures and humidity.
Since , U. This limit was to ensure that indoor formaldehyde levels are below 0.
CPSC [ 40 ] notes that formaldehyde is a colorless, strong-smelling gas. At an air level above 0. Laboratory animal studies have revealed that formaldehyde can cause cancer in animals and may cause cancer in humans. Formaldehyde is usually present at levels less than 0. Indoor areas that contain products that release formaldehyde can have levels greater than 0. CPSC also recommends the following actions to avoid high levels of exposure to formaldehyde:. Radon According to the EPA [ 43 ] , radon is a colorless, odorless gas that occurs naturally in soil and rock and is a decay product of uranium.
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Geological Survey USGS [ 44 ] notes that the typical uranium content of rock and the surrounding soil is between 1 and 3 ppm. Higher levels of uranium are often contained in rock such as light-colored volcanic rock, granite, dark shale, and sedimentary rock containing phosphate. Uranium levels as high as ppm may be present in various areas of the United States because of these rocks. The main source of high-level radon pollution in buildings is surrounding uranium-containing soil. Thus, the greater the level of uranium nearby, the greater the chances are that buildings in the area will have high levels of indoor radon.
A free video is available from the U. Radon, according to the California Geological Survey [ 45 ] , is one of the intermediate radioactive elements formed during the radioactive decay of uranium, uranium, or thorium Radon is the radon isotope of most concern to public health because of its longer half-life 3. The mobility of radon gas is much greater than are uranium and radium, which are solids at room temperature. Thus, radon can leave rocks and soil, move through fractures and pore spaces, and ultimately enter a building to collect in high concentrations.
When in water, radon moves less than 1 inch before it decays, compared to 6 feet or more in dry rocks or soil. USGS [ 44 ] notes that radon near the surface of soil typically escapes into the atmosphere.
However, where a house is present, soil air often flows toward the house foundation because of. Houses are often constructed with loose fill under a basement slab and between the walls and exterior ground.
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This fill is more permeable than the original ground. USGS [ 44 ] states that radon may also enter the home through the water systems. Surface water sources typically contain little radon because it escapes into the air. In larger cities, radon is released to the air by municipal processing systems that aerate the water. However, in areas where groundwater is the main water supply for communities, small public systems and private wells are typically closed systems that do not allow radon to escape. Radon then enters the indoor air from showers, clothes washing, dishwashing, and other uses of water.
These progeny enter the lungs, attach themselves, and may eventually lead to lung cancer. This exposure to radon is believed to contribute to between 15, and 21, excess lung cancer deaths in the United States each year. The EPA has identified levels greater than 4 picocuries per liter as levels at which remedial action should be taken.
Approximately 1 in 15 homes nationwide have radon above this level, according to the U. Smokers are at significantly higher risk for radon-related lung cancer. Radon in the home can be measured either by the occupant or by a professional. Because radon has no odor or color, special devices are used to measure its presence.
Radon levels vary from day to day and season to season. Short-term tests 2 to 90 days are best if quick results are needed, but long-term tests more than 3 months yield better information on average year-round exposure. Measurement devices are routinely placed in the lowest occupied level of the home.
The devices either measure the radon gas directly or the daughter products. The simplest devices are passive, require no electricity, and include a charcoal canister, charcoal liquid scintillation device, alpha tract detector, and electret ion detectors [ 47 ]. All of these devices, with the exception of the ion detector, can be purchased in hardware stores or by mail. The ion detector generally is only available through laboratories.
These devices are inexpensive, primarily used for short-term testing, and require little to no training. Active devices, however, need electrical power and include continuous monitoring devices. They are customarily more expensive and require professionally trained testers for their operation. After testing and evaluation by a professional, it may be necessary to lower the radon levels in the structure. The Pennsylvania Department of Environmental Protection [ 48 ] states that in most cases, a system with pipes and a fan is used to reduce radon. This system, known as a subslab depressurization system, requires no major changes to the home.
The typical mitigation system usually has only one pipe penetrating through the basement floor; the pipe also may be installed outside the house. The Connecticut Department of Public Health [ 49 ] notes that it is more cost effective to include radon-resistant techniques while constructing a building than to install a reduction system in an existing home.
These features create a physical barrier to radon entry. The vent pipe redirects the flow of air under the foundation, preventing radon from seeping into the house. Pesticides Much pesticide use could be reduced if integrated pest management IPM practices were used in the home.
Air pollution control
IPM is a coordinated approach to managing roaches, rodents, mosquitoes, and other pests that integrates inspection, monitoring, treatment, and evaluation, with special emphasis on the decreased use of toxic agents. However, all pest management options, including natural, biologic, cultural, and chemical methods, should be considered.
Those that have the least impact on health and the environment should be selected. Most household pests can be controlled by eliminating the habitat for the pest both inside and outside, building or screening them out, eliminating food and harborage areas, and safely using appropriate pesticides if necessary. Measurable levels of up to a dozen pesticides have been found in the air inside homes.
Pesticides used in and around the home include products to control insects insecticides , termites termiticides , rodents rodenticides , fungi fungicides , and microbes disinfectants. These products are found in sprays, sticks, powders, crystals, balls, and foggers.
Delaplane [ 52 ] notes that the ancient Romans killed insect pests by burning sulfur and controlled weeds with salt. In the s, ants were controlled with mixtures of honey and arsenic. A significant factor with regard to these pesticides used in and around the home is their impact on children.