air flow

Active sources

Have a defined gas flow emitted from source.  Example includes a biofilter or aerated pond.  According to VDI3880, an active source is defined by an average flow velocity of 30m/h…

Read more

Diffuse sources

A source having a specified area or volume that does not have a defined air flow.  Examples include waste dumps, compost piles, sedimentation tank.  An example that is not a…

Read more

Dynamic dilution

Mixing of odourous gas and odour-neutral air measured by flow rate. The consistent introduction of odour-free or odour-neutral air to a concentrated amount of an odourous gas allows for an…

Read more

EN 13725 – Forced Choice Mode

The assessor is presented with two or more ports, of which one presents the stimulus and the other(s) neutral gas.The location of the stimulus in consecutive presentation is randomly distributed…

Read more

Exposure

Exposure is a combination of the amount of a pollutant in the air and the amount of time that person stays in the presence of a pollutant. Exposure determines the…

Read more

Fugitive sources

Unintended release of odours that are not based on a fixed time or have a fixed odour concentration.  These sources may be difficult to measure.  Examples include door opening at…

Read more

Hazardous Air Pollutants (HAPs)

Pollutants released into the atmosphere as particles and volatile organic compounds (VOCs) — including the known carcinogens of benzene and toluene — from a variety of sources such as vehicle…

Read more

New Source Review (NSR)

A Clean Air Act requirement that State Implementation Plans must include a permit review,  which applies to the construction and operation of new and modified stationary sources in Non-attainment areas, to…

Read more

Particulate Matter (PM)

Tiny solid or liquid particles that are suspended in air. Particulate matter is produced from a wide variety of sources like natural and human-caused, large and small. They are comprised…

Read more

VOCs

Volatile Organic Compounds or VOCs are organic chemicals that easily vaporize at room temperature. They are called organic because they contain the element carbon in their molecular structures. VOCs include…

Read more