the ending, reduction, or lessening of harmful materials or substances.
ACH– Air changes per hour. One ACH means a volume of outdoor air equal to the volume of the space being ventilated has entered that space in one hour.
Action Level – Level of exposure to a harmful substance or other hazard (present in a work environment or situation) at which an employer or individual must take the required precautions to protect the buildings inhabitants.
Allergies – An allergy is a hypersensitivity disorder of the immune system. Symptoms include red eyes, itchiness, and runny nose, eczema, hives, or an asthma attack.
Allergic Reaction – Reactions that occur when a person’s immune system reacts to normally harmless substances in the environment.
Alpha Particles – Alpha particles (symbol α ) are a type of ionizing radiation ejected by the nuclei of some unstable atoms. They are large subatomic fragments consisting of two protons and two neutrons.
Asbestos Cement – Building material made from a watered mixture of cement and asbestos.

Backflow Preventer – A check valve installed on a building drain to prevent backup should the drain line receive floodwaters from outside the building, such as due to area flooding or a septic or sewer line backup.
Bacteria – Micro-organisms that have no true nucleus, a single chromosome, and no mitochondria, capable of causing adverse health effects.
Bio-aerosols – Tiny airborne particles that are alive, were once alive, or are a part of something that is or once was alive.
Biocide – A physical or chemical agent that is capable of killing micro-organisms.
Biofilm – A surface layer of micro-organisms.
Boroscope – An instrument used to inspect the inside of a structure through a small hole.
Breathing Zone – Area of a room in which occupants breathe as they stand, sit, or lie down.
BRI – See Building-Related illness
Building-Related Illness – A discrete, identifiable disease or illness that can be traced to a specific pollutant or source within a building. (e.g., Legionnaires’ disease, hypersensitivity pneumonitis) (Contrast with sick building

Carcenogen – A carcinogen is any substance, radionuclide, or radiation that is an agent directly involved in causing cancer.
Central Air Handling Unit (Central AHU)- This is the same as an Air Handling Unit, but serves more than one area.
CFM – Cubic feet per minute.
Chemical Sensitivity – Health problems characterized by effects such as dizziness, eye and throat irritation, chest tightness, and nasal congestion that appear whenever individuals are exposed to certain chemicals. People may react to even trace amounts of chemicals to which they have become sensitized.
Chronic effects – Those occurring after repeated long-term exposure and are seen months or years after initiation of exposure.
Circulation – air moved through the furnace heat exchanger and then through the house to provide heating or cooling. This may not have any outside air
CO – Carbon monoxide.
CO2 – Carbon dioxide.
Coil – Component of HVAC system that acts as a heat exchanger, either adding heat or taking heat away from the air stream.
Combustion – additional air brought into the house to allow furnaces, boilers, clothes dryers, ranges and domestic hot water heaters to burn. If the appliance has “sealed” combustion this air will not affect the air within the house.
Condensation – The process of changing a vapour to a liquid by extracting heat from the vapour.
Conditioned Air – Air that has been heated, cooled, humidified, or dehumidified to maintain an interior space within the comfort zone. (Sometimes referred to as tempered air.)
Constant Air Volume (CAY) System – Refers to a type of HVAC system where air volume is constant and air-stream is either heated or cooled so as to maintain a constant temperature.
Containment Barrier – Containment Barriers help isolate and contain dust, airborne contaminants, odors and mold spores when performing indoor building construction, mold remediation and day-to-day maintenance activities. Containment barriers provide a durable floor to ceiling protective barrier that minimizes the chance of dirt and particle migration from the work zone and allows the remainder of the building to be used normally without
Convection – Movement of molecules (gases) from a region of higher air pressure to a region of lower air pressure. Airflow can also be induced by a temperature gradient (e.g., stack effect).
Criteria Air Pollutants – Include sulphur dioxide, particulates, lead, ozone, nitrogen oxides, and carbon monoxide, all designated by the EPA and which have national standards under the National Ambient Air Quality Standards (NAAQS).

Designated Substance Survey-
The Ontario Occupational Health and Safety Act requires that a list of all designated substances at a project site be provided to all bidders at the tendering stage.  A Designated Substance Survey (DSS) identifies the designated substances present, their locations and concentrations.  This information allows contractors involved in demolition or renovation activities to take appropriate steps to control exposure of workers and the general public to the designated substances that are present.
Developmental Toxin – A chemical that acts as a poison by means of causing adverse effects on the developing organism, including death, structural abnormality, altered growth, and functional deficiency.

E coli – A species of bacterium normally present in intestinal tract of humans and other animals; sometimes pathogenic; can be a threat to food safety.
Encapsulant- A material or substance used for enclosing or sealing contaminated or harmful material.
Endotoxins – Bacterial by-products excreted into the environment.
Environmental Agents – 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 overcrowding).
Epidemiology – The study of the incidence, distribution, and control of disease in a population.
Exhaust Ventilation – Mechanical removal of air from a portion of a building (e.g., piece of equipment, room, or general area).
Exposure Assessment – Analysis of a set of exposure profiles which address for each pollutant, the size of the exposed population, and the routes, duration, frequencies, and intensities of exposure.

False negative
– Test or investigation results that indicate a particular condition does not exist when it actually does.
False positive – Test or investigation results that incorrectly indicate the existence of a particular condition.
Fungi – Any of a group of parasitic lower plants, including moulds and mildews, that lack chlorophyll.

– High efficiency particulate arrestance (filters).
Humidifier – A device to add moisture to air.
HVAC – Acronym for heating, ventilating, and air conditioning system.
Hypersensitivity Diseases – Diseases characterized by allergic responses to animal antigens. The hypersensitivity diseases most clearly associated with indoor air are asthma, rhinitis, and hypersensitivity pneumonitis. Hypersensitivity pneumonitis is a rare but serious disease that involves progressive lung damage as long as there is exposure to the causative agent.
Hypokinesis – abnormally decreased mobility; abnormally decreased motor function or activity.

– Indoor air quality.
IAQ Coordinator – An individual at the school and/or school district level who provides leadership and coordination of IAQ activities.
IAQ Management Plan – A component of the IAQ Tools for Schools Kit, specifically, a set of flexible and specific steps for preventing and resolving IAQ problems.
Immunocompromised – when the body’s natural defences to infection are below normal.
Indicator Compounds – 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).
Irritants – Substances which inflame living tissue by chemical action at the site of contact, causing pain or swelling.

Legionnaires’ disease
– An illness which is sometimes fatal and whose symptoms mimic pneumonia. It is caused by a bacterium (Legionnella pneumophila) and primarily attacks Immunocompromised individuals.

Make-up Air
– Air brought into a building from the outdoors through the ventilation system, which has not been previously circulated through the system.
mg/L (ppm) – milligrams per litre (parts per million). For practical purposes mg/L is assumed to be equal to ppm.
Microbiological Contamination – Infection or pollution by microscopic organisms.
Mold – Growth produced by any of a large group of fungi which has a cottony or furry appearance.
Mold Spores – Reproductive body, produced by active or non active mold , that can develop into a new individual mold growths.
Multiple Chemical Sensitivity (MCS) – A term used by some people to refer to a condition in which a person is considered to be sensitive to a number of chemicals at very low concentrations. There are a number of views about the existence, potential causes, and possible remedial actions regarding this phenomenon.
Mycotoxins – Metabolites produced by fungi that have a broad spectrum of toxic effects ranging from mild acute toxicity to potent carcinogenicity.

Natural Ventilation
– Occurs when outdoor air enters through open windows and doors and through cracks and leaks in the home.
Negative Pressure – 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.

Occupational Standards
– Maximum pollutant concentration levels, usually set by the Occupational Safety and Health Administration (OSHA).
Off-gassing – The production of gases from the chemical deterioration of a substance over time.
Organic compounds – Chemicals that contain carbon. Volatile organic compounds vaporize at room temperature and pressure and are found in many indoor sources including many common household products and building materials.
OSHA – Acronym for the Occupational Safety and Health Administration, a part of the U.S. Department of Labour responsible for determining whether employers are providing working conditions that are safe for employees.

Paint Chips
– A piece of paint that has come loose from a painted surface.
Pathogens – Disease-producing micro-organisms or materials.
PELs – Permissible Exposure Limits (standards set by OSHA), workplace exposure limits established to protect on-the-job workers.
Personal Protective Equipment – Commonly referred to as “PPE”, is equipment worn to minimize exposure to serious workplace injuries and illnesses. These injuries and illnesses may result from contact with chemical, radiological, physical, electrical, mechanical, or other workplace hazards.
PICOCURIE (pCi) – A unit for measuring radioactivity, often expressed as picocuries per liter (pCi/L) of air.
Pollutant pathways – The routes followed by a pollutant from its emission (source) as it travels through a ducts, air streams, etc.
Positive Pressure – Condition that exists when more air is supplied to a space than is exhausted, so that air pressure within that space is greater than that found in surrounding areas.
Post Clearance Testing– Post-remediation verification testing (also called clearance testing) is the inspection and retesting of areas in a building that have undergone remediation work to ensure that the remediation was successful.
Preventative Maintenance – 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.
Psychogenic Illness – This syndrome has been defined as a group of symptoms that develop in an individual (or a group of individuals in the same indoor environment) who are under some type of physical or emotional stress. This does not mean that individuals have a psychiatric disorder or that they are imagining symptoms.
Pschyosocial Factors – Psychological, organizational, and personal stressors that could produce symptoms similar to those caused by poor indoor air quality.
Pulmonary Toxins – Substances that affect the respiratory tract.

– Quality Assurance/Quality Control procedures are used to assess method performance, accuracy, and precision.

Radiant Heat Transfer – Radiant heat transfer occurs when there is a large difference the temperatures of two No surfaces that are exposed to each other, but are not touching.
Radon – A radioactive gas formed by the decay of uranium.
Radioactivity– The property possessed by some elements (as uranium) or isotopes (as carbon 14) of spontaneously emitting energetic particles (as electrons or alpha particles) by the disintegration of their atomic nuclei.
Radon Progeny – Radon particles that can be breathed into the lung, where they continue to release radiation as they further decay. Also known as radon decay products or radon daughters.
RELs – Recommended Exposure Limits (recommendations made by NIOSH)
Remediation – The action of remedying contamination, esp the reversal or stopping of damage to the environment or building in which contamination exists.
Remediation Plan – A remediation plan is a plan which is formulated to address a case of environmental contamination. The goal of a remediation plan is to identify and treat the contamination so that the contaminated area will be usable again.
Reproductive Toxin – A chemical acting as a poison by means of causing adverse effects on the male or female reproductive system (e.g. fertility, pregnancy outcomes).
Risk Assessment – Broadly defined as the scientific activity of evaluating the toxic properties of a substance and its potentials for human exposure, to determine the probability of exposed humans being adversely affected.

– One of three groups of antimicrobials registered by EPA for public health uses.’ EPA considers an antimicrobial to be a sanitizer when it reduces, but does not necessarily eliminate, all the micro-organisms on a treated surface. To be a registered sanitizer, the test results for a product must show a reduction of at least 99.9% in the number of each test micro-organisms over the parallel control.
Saprophytic – Depending at least in part on dead organic matter as a food source.
Sick Building Syndrome – Term that refers to a set of symptoms affecting a number of building occupants during the time they spend in the building and diminish or go away during periods when they leave the building. Cannot be traced to specific pollutants or sources within the building. (Contrast with Building-Related Illness.)
Soil Gases – Gases that enter a building from the surrounding ground (e.g., radon, volatile organics, pesticides)
Source Emissions – Emissions generated at the origin of a pollutant.
Stack Effect – Occurs when a house acts like a chimney. The warm air in the home is lighter than the cold air outside and rises in the building and escapes out the top. The cool air is drawn into the building as the warm air escapes.
Staged Approach – A systematic, step-wise approach to investigation providing built-in decision points at which progress is assessed, and the investigation is redirected as necessary.
STEL – Short-term exposure limit
Syncope – faint; loss of consciousness.
Systemic Toxins – Substances that affect entire organ systems, often operating far from the original site of entry.

Toxic Air Pollutants – Aggregate emissions of the following are determined by the EPA to be toxic -Benzene, 1,3 Butadiene, Polycyclic Organic Matter, Acetaldehyde, Formaldehyde.
TVOCs – Total volatile organic compounds.
TWA – Time-weighted average. The average exposure an individual would experience over the period of an entire shift (usually 8 hours), measured at the breathing zone.

– The chemical element of atomic number 92, a gray, dense radioactive metal used as a fuel in nuclear reactors.

Ventilation Rate
– The rate at which outside air replaces indoor air (also referred to as air exchange rate), expressed in one of two ways-the number of changes of outside air per hour (ACH), or the rate at which a volume of outside air enters per unit of time (cubic feet per minute, or cfm).
Vermiculite – A silver-gold to gray-brown mineral that is flat and shiny in its natural state. When heated to around 1000 degrees C, it pops (or puffs up) which creates pockets of air. This expanded form, and the fact that vermiculite does not burn, made the material suitable for use as insulation.
Viruses – The smallest of all life forms containing either RNA or DNA. Viruses are responsible for a variety of human infections.
VOCs – See Volatile Organic Compounds.
Volatile Organic Compounds (VOCs) – Compounds that evaporate from housekeeping, maintenance, and building products made with organic chemicals. These compounds are released from product that are being used and are in storage. 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. At present, not much is know about what health effects occur at the levels of VOCs typically found in public and commercial buildings.