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Glossary of Mold Related Terms


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Pascal; unit of pressure measurement.


Polycyclic Aromatic Hydrocarbons.

Particulate Matter

A state of matter in which solid or liquid substances exist in the form of aggregated molecules or particles. Airborne particulate matter is typically in the size range of 0.01 to 100 micrometers.


Fine liquid or solid particles such as dust, smoke, mist, fumes, and fog found in air and emissions.


Capable of causing disease.


Microorganisms that can cause disease in other organisms, humans, animals, or plants.


Polychlorinated biphenyls.


Pico Curies per liter; a measure of radon concentration.


Permissible Exposure Limits (standards set by OSHA).


Awareness of the effects of stimuli.


Any form of animal, plant, or terrestrial life that is injurious to health or the environment.


Substance intended to control, prevent, or kill a pest.


A measure of acidity or alkalinity on a scale of 0 to 14 where 7 is neutral. A pH less than 7 is acid and a pH greater than 7 is alkaline or base.


Alkaline builders used in detergents to soften water.


Something that harms plants


Products of incomplete combustion. All particles and gases that are emitted from an object at the time it is burning.


Perimeter induction unit


Air compartment connected to a duct or ducts.

Plug Flow

A flow regime where the flow is predominately in one direction and contaminants are swept along with the flow.


A visible or measurable discharge of a contaminant body from a given point of origin. Can be a visible body of pollution such as smoke coming from a stack or a measured amount such as heat in water coming from a power plant boiler.


Preventive Maintenance

Pollutant Pathways

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


Unwanted by-product of human activity. the presence of matter or energy whose nature, location, or quantity produces undesired environmental effects.

Positive Pressure

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.


Parts Per Billion


Parts Per Million

Pressure, Total

In flowing air, the sum of the static pressure and the velocity pressure.

Pressure, Velocity

In flowing air, the pressure due to the velocity and density of the air.

Preventive 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.


The efficiency with which a person performing a specific function does a job, or the output of a worker under specific environments and conditions.

Psychological Factors

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