Tailings
Residue of raw material or waste separated out during the processing of crops or mineral ores.

TEF
Toxic Equivalent Factor.

TEOM
Tapered Element Oscillating Microbalance.

Thermal Treatment
Use of elevated temperatures to treat hazardous wastes.

Threshold
The lowest dose of a chemical at which a specified measurable effect is observed and below which it is not observed.

Threshold Level
Time-weighted average pollutant concentration values, exposure beyond which is likely to adversely affect human health.

Time-weighted Average (TWA)
In air sampling, the average air concentration of contaminants during a given period.

Total Dissolved Solids (TDS)
All material that passes the standard glass river filter; now called total filterable residue. Term is used to reflect salinity.

Total Suspended Solids (TSS)
A measure of the suspended solids in wastewater, effluent, or water bodies.

Toxic Substance
A chemical or mixture that may present an unreasonable risk of injury to health or the environment.

Toxic Waste
A waste that can produce injury if inhaled, swallowed, or absorbed through the skin.

Transboundary Pollutants
Air pollution that travels from one jurisdiction to another, often crossing international boundaries.

Trial Burn
An incinerator test in which emissions are monitored for the presence of specific organic compounds, particulates, and hydrogen chloride.

Trichloroethylene (TCE)
A stable, low boiling-point colourless liquid, toxic if inhaled. Used as a solvent or metal degreasing agent, and in other industrial applications.

Troposphere
The layer of the atmosphere closest to the earth's surface.

Turbidity
The cloudy appearance of water caused by the presence of suspended and colloidal matter. In the waterworks field, a turbidity measurement is used to indicate the clarity of water. Technically, turbidity is an optical property of the water based on the amount of light reflected by suspended particles. Turbidity cannot be directly equated to suspended solids because white particles reflect more light than dark-coloured particles and many small particles will reflect more light than an equivalent large particle.