What is volatile organic compounds (VOCs)
Volatile organic compounds (VOCs) are emitted as gases from certain solids or liquids. VOCs include a variety of chemicals, some of which may have short- and long-term adverse health effects. Concentrations of many VOCs are consistently higher indoors (up to ten times higher) than outdoors. VOCs are emitted by a wide array of products numbering in the thousands. Examples include: paints and lacquers, paint strippers, cleaning supplies, pesticides, building materials and furnishings, office equipment such as copiers and printers, correction fluids and carbonless copy paper, graphics and craft materials including glues and adhesives, permanent markers, and photographic solutions.
Studies have found that levels of several organics average 2 to 5 times higher indoors than outdoors. During and for several hours immediately after certain activities, such as paint stripping, levels may be 1,000 times background outdoor levels.
Household products including: paints, paint strippers, and other solvents; wood preservatives; aerosol sprays; cleansers and disinfectants; moth repellents and air fresheners; stored fuels and automotive products; hobby supplies; dry-cleaned clothing.
Eye, nose, and throat irritation; headaches, loss of coordination, nausea; damage to liver, kidney, and central nervous system. Some organics can cause cancer in animals; some are suspected or known to cause cancer in humans. Key signs or symptoms associated with exposure to VOCs include conjunctival irritation, nose and throat discomfort, headache, allergic skin reaction, dyspnea, declines in serum cholinesterase levels, nausea, emesis, epistaxis, fatigue, dizziness.
The ability of organic chemicals to cause health effects varies greatly from those that are highly toxic, to those with no known health effect. As with other pollutants, the extent and nature of the health effect will depend on many factors including level of exposure and length of time exposed. Eye and respiratory tract irritation, headaches, dizziness, visual disorders, and memory impairment are among the immediate symptoms that some people have experienced soon after exposure to some organics. At present, not much is known about what health effects occur from the levels of organics usually found in homes. Many organic compounds are known to cause cancer in animals; some are suspected of causing, or are known to cause, cancer in humans.
Methods of measurement
No standards have been set for VOCs in non industrial settings. OSHA regulates formaldehyde, a specific VOC, as a carcinogen. OSHA has adopted a Permissible Exposure Level (PEL) of .75 ppm, and an action level of 0.5 ppm. HUD has established a level of .4 ppm for mobile homes. Based upon current information, it is advisable to mitigate formaldehyde that is present at levels higher than 0.1 ppm.
Methods of control
The range of measurement methods and analytical instruments is large and will determine the sensitivity of the measurements as well as their selectivity or biases. This is why any statement about VOCs that are present in a given environment needs to be accompanied by a description of how the VOCs were measured so that the results can be interpreted correctly by a professional. In the absence of such a description, the statement would have limited practical meaning.
What is radon?
Radon-222 is a radioactive gas released during the natural decay of thorium and uranium, which are common, naturally occurring elements found in varying amounts in rock and soil. Odorless, invisible, and without taste, radon cannot be detected with the human senses.
Radon-222 decays into radioactive elements, two of which -- polonium-218 and polonium-214 -- emit alpha particles, which are highly effective in damaging lung tissues. These alpha-emitting radon decay products have been implicated in a causal relationship with lung cancer in humans.
Radon is an invisible, odorless gas that comes from naturally occurring uranium in soil and water. It can seep into your home through pipes, cracks in your foundation, sumps and drains and other openings. Radon is carcinogenic and can cause lung cancer; it is the leading cause of lung cancer among non-smokers.
Outdoors, where it is diluted to low concentrations in the air, radon poses significantly less risk than indoors. In the indoor air environment, however, radon can accumulate to significant levels. The magnitude of radon concentration indoors depends primarily on a building's construction and the amount of radon in the underlying soil. The soil composition under and around a house affects radon levels and the ease with which radon migrates toward a house. Normal pressure differences between the house and the soil can create a slight vacuum in the home that can draw radon gas from the soil into the building.
Radon gas can enter a home from the soil through cracks in concrete floors and walls, floor drains, sump pumps, construction joints, and tiny cracks or pores in hollow-block walls. Radon levels are generally highest in basements and ground floor rooms that are in contact with the soil. Factors such as the design, construction, and ventilation of the home affect the pathways and sources that can draw radon indoors. Another source of radon indoors may be air released by well water during showering and other household activities. Compared to radon entering the home through soil, radon entering the home through water will in most cases be a small source of risk.
Spreading of radon
The primary source of exposure to radon is indoor or household air. Many houses and buildings have been constructed right on top of radon emitting rocks. Radon daughters are often attached to dust, and you are exposed to them primarily through breathing). They are present in nearly all air. However, background levels of radon in outdoor air are generally quite low, about 0.003 to 2.6 picocuries of radon per liter of air. In indoor locations, such as homes, schools, or office buildings, levels of radon and daughters are generally higher than outdoor levels (2). Cracks in the foundation or basement of your home may allow increased amounts of radon to move into your home. In some areas of the country the amount of uranium and radium in rock types, such as phosphate rock or granite, is high. In these areas radon levels in outdoor air will generally be higher
The radiation released during the process of decay passes into lung tissue and causes lung damage. There is very limited information on whether radon gas can penetrate the skin, but some radon may be able to pass through the skin when you bathe in water containing radon.
Long-term exposure to radon and radon daughters in air increases your chances of getting lung cancer. When exposures are high, noncancer diseases such as thickening of certain tissues of the lungs may occur. This usually occurs within a few days or weeks after exposure to radon. Cancer due to radon exposure takes several years before effects become apparent. This is known from studies of workers exposed to radon in mines, primarily uranium miners, and from tests on laboratory animals. It is not known if radon causes health effects other than to the lung.
Methods of measurement
The EPA and the U. S. Surgeon General recommend testing all homes below the third floor for radon. Data gathered by the EPA national radon survey indicate that elevated radon levels are present in about six million (6,000,000) homes throughout the United States.
Because the radon concentration inside a home is due to factors relating to its structure and geographic location, each individual home must be tested to determine its radon level. Two adjacent houses may have radically different radon levels. And any kind of home can have elevated levels -- new or old, drafty or well-sealed, and basement or non-basement.
Short-term tests measure radon levels for 2 to 7 days, or use a continuous radon monitor for a minimum of 48 hours, depending on the device. While short-term tests do not measure the annual average of level of radon, they do offer a quick and inexpensive way to "screen" for radon in a home.
Long-term testsdetermine the average concentration for a minimum of 90 days. Long-term tests are the best way to estimate the average amount of radon in the home during the year, particularly if a year-long test is done to include both heating and cooling seasons.
Methods of control
Depending on the laws governing radon control in your geographic area, you may need a license or the help of a licensed contractor to mitigate radon levels. Professional contractors sometimes offer radon services, as do many regional environmental agencies. If your home tests positive for radon, seek the help of a professional as dictated by local law.
Different radon control tests measure with different units, and knowing the conversion equivalents may be helpful.
When taking steps toward radon control in your home, you should note that there is no safe radon level. No amount of radon is considered a safe amount of gas. The World Health Organization states that for every 2.7 pCi/L of radon, the risk of lung cancer increases by 16 percent.
What is asbestos?
Asbestos is a mineral fibre. It can be positively identified only with a special type of microscope. There are several types of asbestos fibres. In the past, asbestos was added to a variety of products to strengthen them and to provide heat insulation and fibre resistance.
Because asbestos is often mixed with another material, it's hard to know if you're working with it or not. But, if you work in a building built before the year 2000, it's likely that some parts of the building will contain asbestos.
The main sources of indoor air contamination are linked to the presence of friable asbestos materials such as the sprayed asbestos applied to the ceilings and walls of some public buildings up to the late 1970s. In public buildings and on ships, wrapped asbestos was used extensively to insulate pipes; places such as boiler rooms may be contaminated when these insulating materials deteriorate. Asbestos workers’ clothing may be an important contamination source inside buildings and residences. Asbestos is also found in some construction materials such as insulating materials for boilers and pipes, floor and ceiling tiles, some paints, and some papers and textiles. However, in most cases these are non-friable materials.
Spreading of asbestos
Asbestos is found in many products used in buildings, including ceiling tiles, pipe insulation, boilers and sprayed coatings.
Some of the more common uses of Asbestos in buildings are:
- Sprayed coating- found as fire protection on structural supports (eg columns and beams). It is a high hazard asbestos product and can generate very high fibre levels if disturbed,
- Pipe Insulation- asbestos thermal pipe lagging is a high hazard asbestos product.
- Asbestos insulating board (also referred to as AIB) ceiling and door panels- AIB is a high hazard asbestos product and can generate high levels of fibres if the board is cut or drilled.
- AIB window panel - Like other AIB, this is a high hazard asbestos product, and if in good condition should be left undisturbed.
- Floor tiles - Vinyl (PVC) or thermoplastic tiles contain asbestos.
- Asbestos cement roof sheeting - Asbestos cement sheeting is often found on industrial building roofs and walls.
- Textured decorative coating (such as Artex) - Textured coatings contain a small amount of asbestos. The asbestos is well bonded and fibres are not easily released. However, it is still an asbestos product, and as such, needs to be worked with safely.
Asbestos tends to break down into a dust of microscopic size fibers. Because of their size and shape, these tiny fibers remain suspended in the air for long periods of time and can easily penetrate body tissues after being inhaled or ingested. Because of their durability, these fibers can remain in the body for many years and thereby become the cause of asbestos related diseases.
Symptoms of these diseases generally do not appear for 10 to 30 years after the exposure. Therefore, long before its effects are detectable, asbestos related injury to the body may have already occurred. There is no safe level of exposure known, therefore exposure to friable asbestos should be avoided.
Methods of measurement
Three methods for identifying asbestos are currently used: Polarised Light Microscopy (PLM), X-ray Diffractometry (XRD), and Electron Microscopy (EM).(5) The PLM method generally suffices, but useof one of the other methods for verification of difficult samples may be required. It is important that the analysis be performed by a competent laboratory to ensure accurate results
Methods of control
The control of asbestos hazards should utilise the most appropriate method applicable to the particular circumstances. Based upon the assessment of the condition of the asbestos, the possibility of further damage or deterioration, and the potential for exposure of personnel to airborne asbestos, the methods of
control include: deferment, encapsulation or sealing, enclosure and removal.