Air Quality

The VFA team consists of an unique combination of scientists, technicians and designers, which results in VFA being a source for expert knowledge.

Contact us

Call us at +31 (0) 10 - 4278733 or contact us by email if you want information or if you have questions .


Subscribe to newsletter

Go to our website to subscribe to our newsletter

Indoor Air Quality Definitions/Glossary

Acid Aerosol

Acidic liquid or solid particles that are small enough to become airborne. High concentrations of acid aerosols can be irritating to the lungs and have been associated with some respiratory diseases, such as asthma.


A dispersion in air of liquid droplets or solid particles, which range in size from 0.01 to 100µm and which can remain suspended in air for some period of time.


A substance capable of causing an allergic reaction because of an individual's sensitivity to that substance.

Allergic Rhinitis

Inflammation of the mucous membranes in the nose that is caused by an allergic reaction.

Animal Dander

Tiny scales of animal skin.


Agent that kills microbial growth. See disinfectant, sanitizer, and sterilizer.


One-celled organisms, members of the Protista, a biological classification.

Bio aerosol

An aerosol of biological material, such as microorganisms or body fluids

Breathing zone

Area of the room in which occupants breathe as they stand, sit, or lie down.

Building-Related Illness

A discrete, identifiable disease or illness that can be traced to a specific pollutant or source within a building. (Contrast with "Sick building syndrome").

Chemical Sensitization

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."

Clean Air Delivery Rate (CADR)

The CADR indicates the volume of filtered air delivered by an air cleaner.


One of three groups of antimicrobials registered by EPA for public health uses. EPA considers an antimicrobial to be a disinfectant when it destroys or irreversibly inactivates infectious or other undesirable organisms, but not necessarily their spores. EPA registers three types of disinfectant products based upon submitted efficacy data: limited, general or broad spectrum, and hospital disinfectant

Environmental Tobacco Smoke, or ETS

Mixture of smoke from the burning end of a cigarette, pipe, or cigar and smoke exhaled by the smoker (also second-hand smoke or passive smoking).


Applied science that investigates the impact of people’s physical environment on their health and comfort (e.g., determining the proper chair height for computer operators).


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

Humidifier Fever

A respiratory illness caused by exposure to toxins from microorganisms found in wet or moist areas in humidifiers and air conditioners. Also called air conditioner or ventilation fever.

Hypersensitivity Pneumonitis

A group of respiratory diseases that cause inflammation of the lung (specifically granulomatous cells). Most forms of hypersensitivity pneumonitis are caused by the inhalation of organic dusts, including moulds.


An adjective that describes anything which pertains to Microbiology, which is a branch of biology dealing with microorganisms.


Life forms too small to be viewed by the unaided eye.


Release of gases such as organic vapours, from a building material after the manufacturing process is complete.

Organic Compounds

Chemicals that contain carbon. Volatile organic compounds vaporize at room temperature and pressure. They are found in many indoor sources, including many common household products and building materials.

Picocurie, or pCi

A unit for measuring radioactivity, often expressed as picocuries per liter, or pCi/L, of air.

Pollutant pathway

Route of entry of an airborne contaminant from a source location into the occupant breathing zone through architectural or mechanical connections (e.g., through cracks in walls, vents, open windows.

Pressed Wood Products

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.

Psychosocial factors

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

Radon, or Rn, and Radon Decay Products

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.


One of three groups of antimicrobials registered by EPA for public heath uses. EPA considers an antimicrobial to be a sanitizer when it reduces but does not necessarily eliminate all the microorganisms 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 organism over the parallel control.

Sick Building Syndrome

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 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 organic compounds)


One of three groups of antimicrobials registered by EPA for public health uses. EPA considers an antimicrobial to be a sterilizer when it destroys or eliminates all forms of bacteria, fungi, viruses, and their spores. Because spores are considered the most difficult form of a microorganism to destroy, EPA considers the term sporicide to be synonymous with sterilizer.

Tracer gases

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

Ventilation Rate

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 meter per minute, or "m3/h").


Are considered part of the microbial world, but they are really not organisms because they are not cells. A Virus particle is a piece of genetic material protected by a surrounding protein coat.

Volatile Organic Compounds (VOCs)

Compounds that vaporize (become a gas) at room temperature. Common sources which may emit VOC’s 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. At present, not much is known about what health effects occur at the levels of VOCs typically found in public and commercial buildings.