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HEPA Filter

HEPA stands for High Efficiency Particulate Air filters used in HVAC systems, vacuum cleaners, etc. A HEPA filter removes a minimum of 99.97% of contaminants at 0.3 microns in size. In comparison, a human hair is about 60-75 microns in diameter. Particles less than 35 microns can't be seen with the naked eye. Pollen is in the 10-100 micron range, with dust in the .5-5 micron range. Particles under 5 microns can penetrate deep into the lungs.

Vacuum cleaners with HEPA filters trap a great deal more of airborne particles than other vacuums that simply recirculate them back into the air.

True or absolute HEPA filters must pass a test to be considered HEPA worthy. True HEPA filters will have a serial number assigned to them if they are able to trap at least 99.97 percent of particles of .3 microns. These test results will be printed on the filter. True or absolute HEPA filters may be more expensive than other HEPA filters, but they must perform at a certain standard to receive the distinction of true or absolute HEPA.


Heating, Ventilation and Air Conditioning.

Household Products Database

A database containing health and safety information on various products found around the home.  Material is compiled by the U.S. Department of Health & Human Services.  For an individual product name, you can find information on the brand and manufacturer as well as data from the Material Safety Data Sheets (MSDS) that include: health effects, handling/disposal, and ingredients.  It is part of the National Library of Medicine, and can be found on the Internet at 


Hydrocarbons are chemical compounds consisting entirely of carbon and hydrogen. They are a subset of organic compounds. The carbon atoms form the framework, and the hydrogen atoms attach to them.

Hydrocarbons come in a variety of forms. They may be gases (methane and propane), liquids (hexane and benzene), waxes (paraffin wax), or polymers (polyethylene and polystyrene). Hydrocarbons can be processed to create plastics.

The primary source of hydrocarbons here on Earth is through fossil fuels – coal, petroleum, oil, and natural gas.  These serve as fuels, lubricants, and the raw materials for producing plastics, fibers, rubbers, solvents, explosives, and industrial chemicals.  All burn to carbon dioxide and water if there is enough oxygen, or to carbon monoxide if there is no water. The combustion of hydrocarbons produces smoke and soot, generating pollution, which is responsible for smog and acid rain.


Hypoallergenic refers to anything that helps to decrease the severity of a person’s allergic reactions.  For example, manufacturers produce hypoallergenic products such as pillows, shampoos, perfumes, etc.

Integrated Risk Information System (IRIS)

Integrated Risk Information System (IRIS) is an online hazard identification and dose-response assessment for over 500 chemicals.  It is part of TOXNET.  It contains data in support of human health risk assessment as compiled by the U.S. Environmental Protection Agency (EPA).  IRIS data, focusing on hazard identification and dose-response assessment, is reviewed by work groups of EPA scientists and represents EPA consensus. Among the key data provided in IRIS are EPA carcinogen classifications, unit risks, slope factors, oral reference doses, and inhalation reference concentrations.  It can be found on the Internet at

Lemons, As a Cleaning Agent

See “Citrus Oil”


When an alga and fungus physically intertwine in a very close symbiotic relationship, they actually form an entirely new growth called lichen. Lichen is a kind of primitive plant species that's nothing more than strands of alga linked with roots and branches of a fungus that together absorb minerals from the ground and conduct photosynthesis.  Lichen can grow almost anywhere, from moist bark to recently cooled lava to frozen rocks.


As with Salmonella, listeria is a type of bacteria that is carried in animals. If a food is contaminated, it can be passed onto humans if the food is not cooked thoroughly or if people handling contaminated food touch various surfaces causing cross-contamination. Listeria can potentially be fatal. It can present with many symptoms that can be confused with many other illnesses such as fever, headache and muscle stiffness.

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