Lesson 7.05 Indoor Air Pollution

Background

Indoor air pollution comes from sources that release gases or particles into the air that negatively affect the air quality within a structure or building. Human activities such as smoking tobacco products, using fireplaces, running fossil fuel-burning equipment ex. furnaces , spraying pesticides, using cleaning supplies, and painting can all contribute to lower indoor air quality and indoor air pollution. All of these examples can release particles or gases into the air that can cause indoor air pollution and affect human health.

• Smoking, building fires, and running fossil fuel burning devices indoors can potentially put harmful carbon monoxide, as well as harmful particulate matter, into the air.

• Household products that are commonly used in homes and offices — such as cleaners, paints, pesticides, glues, and air fresheners — can release harmful chemicals into the air that can affect the quality of indoor air.

• Volatile organic compounds (VOCs) are found in many carpets, upholstery, paint, and gasoline. These compounds can cause indoor air pollution and present risks to human health.

• Building materials used in construction of structures can also contribute to poor indoor air quality and cause indoor air pollution.

 

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Building Materials

Many older buildings were constructed with materials that can also contribute to poor indoor air quality. In older buildings, asbestos can be found as a component of many of the building materials used for construction, such as roofing shingles, insulation, ceiling and floor tiles, and cement. Asbestos is a mineral fiber that occurs in rocks and soil and was widely used in construction materials because of its fiber strength and resistance to heat. When these materials are disturbed cut, sanded, or otherwise disturbed during remodeling and the asbestos is broken, small particles of asbestos can enter the air. Exposure to asbestos can cause lung problems such as mesothelioma, a cancer that affects the tissue lining in the lungs.

Workers must use protective gear when removing asbestos from buildings.

Old buildings and homes may also be painted with lead-based paint. If this type paint is disturbed through remodeling or sanding, lead particles can enter the air. Lead can cause serious problems, especially in children, if inhaled. Lead poisoning can cause damage to the brain, nervous system, kidney, and liver; developmental delays; and in some cases, death.

 

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Natural Pollutants

There are also natural pollutants that can lower indoor air quality and cause indoor air pollution. Radon is a naturally occurring gas that is formed when uranium that is found in some rocks and soil breaks down. It can enter buildings by diffusion through the soil or release from concrete. Breathing in radon can damage the lungs and eventually lead to lung cancer.

Living organisms can also be sources of indoor air pollution. Pests such as dust mites can release particles into the air that can contribute or worsen respiratory problems such as asthma. Dander from pets is another example of an allergen allergy causing agents that produce inappropriate or exaggerated responses of the immune system to substances caused by living organisms that can get into the air and degrade indoor air quality. Microscopic organisms organisms that cannot be seen without the assistance of magnification sources, such as microscopes such as mold fungi and mildew can produce spores that can contribute to indoor air pollution. These are also known allergens that can irritate the respiratory system.

 

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Prevention

One of the most important factors that contributes to and intensifies indoor air pollution is poor ventilation. Ventilation allows for air movement and mixing within the building and between air inside the building and outside. This helps keep indoor air pollutants from becoming concentrated in one area. When there is insufficient ventilation, the effects on air quality are greater.

If you will think back to the previous lesson, thermal inversions caused stable air preventing distribution of pollutants in the air. This caused the pollutants to become more concentrated and their effects on the environment to increase. The same is true for buildings. Because warmer air tends to travel to cooler air, newer homes tend to have better insulation to keep warm air inside during the winter and warm air outside during the summer. This cuts down on ventilation because air outside the structure cannot mix with the air inside the structure. So you can save both money and energy on power through this separation, but indoor air pollution is made worse.

An air conditioning unit: 1. The coils and pipes in an air conditioning unit contain refrigerant gas. The refrigerant gas enters the compressor as warm, low-pressure gas and leaves it as hot, high-pressure gas. 2. In the condenser coils, hot, compressed refrigerant gas loses heat to the outdoor air and becomes liquid while it is still warm. The warm, liquid refrigerant passes through the tiny opening of the expansion valve, expands, and partly turns to gas at a low temperature. 3. In the cooling coils, the refrigerant takes up heat from the indoor air and leaves the coils as warm, low-pressure gas. The indoor air gives up heat to the refrigerant in the cooling coils and also loses moisture as it is chilled. 4. The moisture condenses on the coils and trickles down to outside drain holes. 5. Cooled air is blown back into the room. Note that the indoor and outdoor air never mix during this process. Image courtesy of Wikimedia Commons user Pbroks13.

Fans and heating/air conditioning systems can also help with air circulation within the house and between the outside and inside air. However, it is important to make sure that the systems are properly maintained and that filters are used to help remove allergens a substance that causes an exaggerated or inappropriate response from the immune system; or simply an allergic reaction and other particles from the air. Therefore to help reduce indoor air pollution, it is essential that structures are properly ventilated to allow air to flow and mix. Humidity humidity is the amount of moisture/water vapor that is in the air is also another factor that can determine indoor air quality. Low humidity can cause eye irritation, dry skin, and rashes. High humidity can contribute to the growth of mold and dust mites which produce particles that cause air pollution. Therefore, it is important to control humidity within structures to help reduce natural indoor air pollutants.

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Resources

• Visit Tips to Improve Indoor Air Quality to see actions that can be taken to improve indoor air quality.
• Also visit EPA: Indoor Air Quality (IAQ).
• Finally, go to The Health Impacts of Indoor Air Quality to learn how indoor air quality can impact your body.

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