| Made from Recycled Materials | This is a phrase often used when all or part of an item is made from a previously manufactured material or product. |
| Magnahelic Gauge | A type of pressure-measuring device. |
| Make-Up Air | Outdoor air that enters a house to replace air that is exhausted from the house. |
| Manometer | A gauge for measuring air-pressure differences, of which there are several types. |
| Manufactured home | A home that is wider than 8 feet and longer than 40 feet (for an area greater than 320 square feet); built on a permanent chassis and assembled in a manufacturing plant. |
| Masonry | Building construction using materials such as concrete, tile and glass blocks, stone, brick and brick veneer. |
| Mats | Want to stop dirt and dust at the door so it does not damage floors or become airborne? Try a set of these. |
| Mattress | Turn and vacuum twice a year for better sleep — and better health. |
| MCS | Here’s what multiple chemical sensitivity means. |
| MDF | Medium density fiberboard (MDF) is a manufactured wood product widely used in home construction. MDF is produced from fine wood fibers which are bonded with resins or glue. |
| Mechanical Ventilation | The process of supplying air to, and removing air from, a house using a fan. |
| Media Filter | A filter that relies on a fibrous material, usually polyester or fiberglass, to physically strain particulates out of the air. |
| Medium Density Fiberboard | MDF is a manufactured wood product widely used in home construction that is produced from fine wood fibers which are bonded with resins or glue. |
| Medium-Efficiency Filter | A particulate filter, usually in the 30–40% efficiency range when measured using the atmospheric dust spot test. |
| MERV | Stands for Minimum Efficiency Reporting Value. |
| Metal Cabinets | Often overlooked, metal cabinets can be an attractive, low-odor, easy to clean, and durable option. |
| Microban | It’s how advancing technology helps people keep bacteria at bay.
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| Microbes | The scientific name for what many people call germs or bugs. Microbes contribute to bad smelling bathrooms, but also function as natural cleaning agents. |
| Micron | A millionth of a meter. |
| Microwaves | Microwaves are a form of electromagnetic radiation; that is, they are waves of electrical and magnetic energy moving together through space. |
| Mildew | It’s usually another name for mold. |
| Mixed-Gas Sensor | A device that senses oxidizable gases in the air and can be used to control a ventilation system. |
| Modular home | A home that is built in a factory in sections, transported to a site, lifted from the transport by crane, and rested on a prebuilt foundation. |
| Modulating Damper | A motorized damper that can be opened and closed a variable amount. |
| MRSA | Info about drug-resistant staph infections. |
| MSDS | What’s a Material Safety Data Sheet, anyway? |
| MTBE | MTBE (methyl tertiary-butyl ether) is a chemical compound that is manufactured by the chemical reaction of methanol and isobutylene. MTBE is produced in very large quantities (over 200,000 barrels per day in the U.S. in 1999) and is almost exclusively used as a fuel additive in motor gasoline. |
| Multi-Port Ventilator | An exhaust device having several suction connections for running ducts from different rooms. |
| Multiple Chemical Sensitivity (MCS) | A medical condition involving hypersensitivities to a wide variety of common air and food contaminants at very low levels. |
| Mutagen | A substance that causes changes in chromosomes or genes. |
