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Types of Indoor Air Pollution
Posted under air cleaner purifier
The EPA, in 1995, issued a statement to the U.S. Senate declaring that, Indoor air pollution is now our nation’s number one environmental health concern.
In light of ever-increasing energy costs, Americans are sealing their homes and buildings with better fitting windows, more effective insulation, and molding. New home and building designs have focused on improved energy efficiencies. We’ve effectively created structures that cannot breathe, causing stale air to circulate over and over without being thoroughly cleaned. In addition, the use of synthetic building materials has increased, leading to more emissions into the occupied spaces, especially when new. On top of this, studies show that most people spend most of their time indoors.
When homes and buildings are sealed up like this, moisture cannot escape. An increase in moisture can lead to mold growth. Air passing over the mold disrupts it and can lead to mold spores and fragments becoming airborne where they can be breathed in. Dust can harbor bacteria and mold. VOCs are Volatile Organic Compounds that come from common household items, such as cleaners, pesticides, paint and sealants, and of course tobacco smoke. In fact, tobacco smoke is a very complex mixture of chemicals, vapors, and particles that can remain airborne for many hours.
Types of Indoor Air Pollution
- Particulates — Particulate matter in the air is called an aerosol, which includes solid and liquid particles. Particles in the size range from about 0.001 to 10 µm (”micron” or “micrometer”) can remain airborne for long periods of time. Cat dander, which is an allergen to many people, is about 1µm and can remain airborne for several hours. Particles larger than 10 µm, up to 100 µm settle out of air in a matter of minutes.
The vast majority of airborne particulates are too small to be seen with the naked eye. One with good vision can see particles down to about 20 to 40 µm. A human hair is about 100 µm thick. Dust that you see on surfaces is a mixture of many different particles that have fallen out of the air and have stuck together. Human skin scales make up a large part of common household dust. Others are animal dander (skin), fibers from clothing, carpet, and other fabrics, food particles, soil or dirt, parts of plants, and parts of microscopic creatures, such as dust mites, fungus, and bacteria.
- Microbes – Microbe is short for microorganism, which simply means a small organism. More to the point, they are typically too small to be seen with the unaided eye. There are many different types and thousands and thousands of species of microbes. The ones that are important to indoor air quality are bacteria, fungus (mold and mildew). Bacteria are usually 1 µm or less in size. Mold spores are usually about 2 to 10 µm in size and can cause allergy in sensitive individuals when breathed in. Mildew is a common name for fungus that is growing on plants, fabrics, and other objects.
- Gases, Odors, and VOCs – All odors are gases, but not all gases are odors. That means that if you can smell a chemical in the air, it is a gas. One cannot smell a solid or a liquid until a portion of it enters the air. An important term for this is volatility. This simply refers to how easily a chemical can vaporize and become a gas. VOCs are volatile organic compounds and are very important to the study of indoor air quality. Studies have shown that more than 350 VOCs have been found at levels exceeding 1 ppb (part per billion). Some of the common sources for VOCs are building materials and furnishings, household and personal care products, automotive products, hobby supplies, and tobacco smoke. Tobacco smoke alone can contain thousands of compounds including, gases, particulates, and VOCs.
Indoor Air Pollution Sources
This chart lists some of the most common pollutants and their sources found in homes and buildings today.
Category Pollutants Sources Particulate Dust Humans, fabrics, outdoor air Particulate Pollen Outdoor air, plants, transferred from clothing Particulate Tobacco Smoke, Smokers Particulate Animal Dander Animals Microbial Fungi - Mold Spores Mold in HVAC ducts, carpets, plants, outdoor air Microbial Bacteria Humans, pets, outdoor air, waste containers, toilets, HVAC ducts Gas Methyl mercaptan Plastic, natural gas and propane additive Gas Butyl acetate Lacquer, industrial chemicals Gas Methyl methacrylate Plastic, paint, solvents Gas d-limonene Cleaners, fresheners Gas Styrene Plastic Gas Toluene Solvents Gas Hydrogen sulfide Toilet vents (water)
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