Chemical emissions are gases or particulates that have been released into the air.

Carbon monoxide is a highly toxic gas that is colorless, odorless and tasteless. It is created by the incomplete burning of natural gas or any other material containing carbon, including gasoline, kerosene oil, propane, coal and wood.

Combustion pollutants are byproducts of the combustion or burning process. Burning fuels such as coal, oil, gas, and wood produces many pollutants, such as sulfur dioxide, nitrogen oxides and particulates. Combustion also produces airborne emissions and solid waste such as ash and sludge.

Household dust is composed of a wide variety of particles including dead skin from humans and pets, finely ground plant and insect parts, minute particles of sand and soil, and fabric fibers. Daily activities can stir up dust into the air. Dust can trigger allergic reactions in sensitive people, and can cause sneezing, runny nose and itchy/watering eyes.

Dust mites are tiny microscopic creatures related to ticks and spiders. Dust mites feed on skin flakes and can be found throughout the home, in mattresses, pillows, carpets and furniture. They produce airborne particles that can trigger allergic reactions or asthma episodes when inhaled by people who are sensitive to them.

Dust mite debris is made up of the excrement and fragments of dust mites.

The electrostatic charge of Filtrete air filters acts like a magnet to attract and capture particles that can pass through fiberglass filters or other non-charged pleated filters. A Filtrete filter with electrostatically charged fibers performs better than non-electrostatic filters. The actual effectiveness of an air filter in allergen reduction depends on a variety of factors including the amount of air that the filter processes, the nature of the allergens and the rate at which the allergens are being introduced into the home. Electrostatic filters are most effective when new and clean.

A forced air system is a heating and cooling system in which air is blown by a fan through air channels or ducts to rooms.

Formaldehyde is a volatile organic compound (VOC). Potential sources in the home include pressed wood products such as particleboard or fiberboard, smoking, and glues and adhesives.

HEPA stands for High Efficiency Particulate Air. This is a rating system used by the Department of Energy to denote an air cleaner or filter that is 99.97% efficient or better at removing 0.3 micron-sized particles from the air passing through it.

An irritant is a substance that, when breathed in, irritates the airways and can trigger asthma symptoms. Common examples include strong perfumes, cigarette smoke, and fumes from harsh cleaning fluids.

One micron is one millionth of a meter or approximately 1/25,000 of an inch. For comparison, a human hair is 50-70 microns thick.

The 3M MPR (Microparticle Performance Rating) reports a filter's ability to capture tiny particles between 0.3 and 1 micron in size.

Microparticles are tiny airborne particles measuring between 0.3 and 1.0 micron. These include fine dust, smoke, smog, bacteria and some pet dander and pollen particles.

Mold spores are generated from mold, which is a fungus that grows in humid conditions. These spores can produce allergic reactions.

Non-electrostatic filters include 3-month pleated, washable and fiberglass filters that do not have electrostatically charged fibers. Filtrete 1" and 4" residential filters with electrostatically charged fibers have been proven to perform better than 1" and 4" residential non-electrostatic filters.