American Society for Testing and Materials.

The rate at which outside air replaces indoor air in a space. Expressed in one of two ways: the number of changes of outside air per unit of time in air changes per hour (ACH); or the rate at which a volume of outside air enters per unit of time - cubic feet per minute (cfm).

This refers to equipment used to provide conditioned air to a space. The air handler unit generally includes a blower or fan, heating and/or cooling coils, and related equipment such as controls, condensate drain pans, and air filters. Does not include duct work, registers or grilles, or boilers and chillers.

Biological material, including bacteria, viruses, fungi, mold spores, pollens, skin flakes and insect parts are ubiquitous in indoor environments. These particulates range from less than one to several microns in size. When airborne, they are usually attached to dust particulates of various sizes so that all sizes of airborne particulates may include them.

Agent that kills microbial growth.

Agents derived from, or that are, living organisms (e.g., viruses, bacteria, fungi, and mammal and bird antigens) that can be inhaled and can cause many types of health effects including allergic reactions, respiratory disorders, hypersensitivity diseases, and infectious diseases. Also referred to as "microbiologicals" or "microbials."

That area of a room in which occupants breathe as they stand, sit, or lie down.

Space located above the suspended ceiling that accommodates the mechanical and electrical equipment and that is used as part of the air distribution system. The space is kept under negative pressure.

The amount of air, in cubic feet, that flows through a given space in one minute.

Evidence suggests that some people may develop health problems characterized by effects such as dizziness, eye and throat irritation, chest tightness, and nasal congestion that appear whenever they are exposed to certain chemicals. People may react to even trace amounts of chemicals to which they have become "sensitized."

Start-up of a building that includes testing and adjusting HVAC, electrical, plumbing, and other systems to assure proper functioning and adherence to design criteria. Commissioning also includes the instruction of building representatives in the use of the building systems.

Air that has been heated, cooled, humidified, or dehumidified to maintain an interior space within a carefully defined "comfort zone."

Controls that vary airflow through an air outlet, inlet, or duct. A damper position may be immovable, manually adjustable or part of an automated control system.

Components of the ventilation system that distribute and return air to promote air circulation in the occupied space. Generally speaking, supply air enters a space through a diffuser or vent and return air leaves a space through a grille.

A dip in the drain pipe of sinks, toilets, floor drains, etc., which is designed to stay filled with water, thereby preventing sewer gases from escaping into the room.

Dust is comprised of particles in the air that settle on surfaces. Large particles settle quickly and can be trapped by the body's defense mechanisms. Small particles are more likely to be airborne and are capable of passing through the body's defenses and entering the lungs.

Conditions other than indoor air contaminants that cause stress, comfort, and/or health problems (e.g., humidity extremes, drafts, lack of air circulation, noise, and over-crowding).

Mixture of smoke from the burning end of a cigarette, pipe, or cigar and smoke exhaled by the smoker.

The science that investigates the impact of people's physical environment on their health and comfort (e.g., chair design, monitor location, desk configuration or height, etc.)

Mechanical removal of air from a portion of a building (e.g., piece of equipment, room, or general area).

Formaldehyde is a colorless water-soluble gas. Due to its wide use, it is frequently considered separately from other volatile organic compounds (VOCs)

Any of a group of parasitic lower plants that lack chlorophyll, including molds and mildews.

High efficiency participate air (HEPA) filtering equipment that has a 99.97% efficiency at .3 micrometers.

Heating, ventilation, and air-conditioning system.

Diseases characterized by allergic responses to pollutants. The hypersensitivity diseases most clearly associated with indoor air quality are asthma, rhinitis, and hypersensitivity pneumonitis.

A group of respiratory diseases that cause inflammation of the lung. Most forms of hypersensitivity pneumonitis are caused by the inhalation of organic dusts, including molds.

Indoor air quality.

An individual (usually with facility management) who provides leadership and coordination of all IAQ activities.

A set of flexible and specific steps for preventing and resolving IAQ problems in any kind of commercial facility.

Integrated pest management.

Chemical compounds, such as carbon dioxide, whose presence at certain concentrations may be used to estimate certain building conditions (e.g., airflow, presence of sources).

Particles and dust, fibers, mists, bioaerosols, and gases or vapors.

See "Outdoor Air Supply."

See "Biological Contaminants."

A condition in which a person reports sensitivity or intolerance (as distinct from "allergic") to a number of chemicals and other irritants at very low concentrations.

Condition that exists when less air is supplied to a space than is exhausted from the space, so the air pressure within that space is less than that in surrounding areas. Under this condition, if an opening exists, air will flow from surrounding areas into the negatively pressurized space.

The two most prevalent oxides of nitrogen are nitrogen dioxide (NO2) and nitric oxide (NO). Both are toxic gases with NO2 being a highly reactive oxidant, and corrosive. NO gradually reacts with the oxygen in the air to form NO2.

Air brought into a building from the outdoors (often through the ventilation system) that has not been previously circulated through the system. Also known as "Make-Up Air."

Permissible Exposure Limits (standards set by the Occupational, Safety and Health Administration).

Air compartment connected to a duct or ducts.

PM

Avenues for distribution of pollutants in a building. HVAC systems are the primary pathways in most buildings; however all building components interact to affect how air movement distributes pollutants.

Condition that exists when more air is supplied to a space than is exhausted, so the air pressure within that space is greater than that in surrounding areas. Under this condition, if an opening exists, air will flow from the positively pressurized space, outward to surrounding areas.

Parts per million.

A group of materials used in building and furniture construction that are made from wood veneers, particles, or fibers bonded together with an adhesive under heat and pressure.

Primarily done on a building's mechanical systems, this involves a regular and systematic inspection, cleaning, and replacement of worn parts, materials, and systems. Preventive maintenance helps to prevent parts, material, and systems failure by ensuring that parts, materials and systems are in good working order.

Psychological, organizational, and personal stressors that could produce symptoms similar to those caused by poor indoor air quality.

Radon is a radioactive gas formed in the decay of uranium. The radon decay products (also called radon daughters or progeny) can be breathed into the lung where they continue to release radiation as they further decay.

Situation that occurs when the air being exhausted from a building is immediately brought back into the system through the air intake and other openings in the building envelope.

Recommended Exposure Limits (recommendations made by the National Institute for Occupational Safety and Health (NIOSH)).

Situation that occurs when the supply air flows to return or exhaust grilles before entering the breathing zone (area of a room where people are). To avoid short-circuiting, the supply air must be delivered at a temperature and velocity that results in mixing throughout the space.

Term that refers to a set of symptoms that affect some number of building occupants during the time they spend in the building and diminish or go away altogether during periods when they leave the building. (Contrast with Building Related Illness.)

Sources of indoor air pollutants. Indoor air pollutants can originate within the building or be drawn in from outdoors. Common sources include people, fixtures and furnishings, photocopiers, plants, food, etc.

The overall upward movement of air inside a building that results from heated air rising and escaping through openings in the building super structure, thus causing an indoor pressure level lower than that in the soil gas beneath or surrounding the building foundation.

Condition that exists when an equal amount of air is supplied to and exhausted from a space. At static pressure, equilibrium has been reached.

Compounds, such as sulfur hexaflouride, which are used to identify suspected pollutant pathways and to quantify ventilation rates. Trace gases may be detected qualitatively by their odor or quantitatively by air monitoring equipment.

Threshold Limit Values (guidelines recommended by the American Conference of Governmental Industrial Hygienists).

Defined as the total air, which is a combination of the air brought inside from outdoors and the air that is being recirculated within the building.

The rate at which indoor air enters and leaves a building. Expressed in one of two ways: the number of changes of outdoor air per unit of time (air changes per hour, or "ach") or the rate at which a volume of outdoor air enters per unit of time (cubic feet per minute, or "cfm").

Compounds that vaporize (become a gas) at room temperature. Common sources which may emit VOCs into indoor air include housekeeping and maintenance products, and building and furnishing materials. In sufficient quantities, VOCs can cause eye, nose, and throat irritations, headaches, dizziness, visual disorders, memory impairment; some are known to cause cancer in animals; some are suspected of causing, or are known to cause, cancer in humans.