CASA — Clean Air Strategic Alliance is a multi-stakeholder society sponsored by the Departments of Health, Energy, and Environment which provies a forum to discuss and address issues related to air quality in the province.
CH4 — methane is a colorless, odourless gas, which is the most common hydrocarbon in the earth's atmosphere. It is of significance as a greenhouse gas responsible for global warming. About 20% of the total greenhouse effect is attributed to methane.
Critical Load — the highest deposition load that will not cause chemical changes leading to long-term harmful effects on the most sensitive ecological systems.
NOx — oxides of nitrogen are formed when nitrogen combines with oxygen during the combustion of fossil fuels. Other sources are the natural degradation of vegetation and the use of chemical fertilizers. Oxides of nitrogen affect visibility and lead to ozone formation. For monitoring purposes nitrogen oxides are considered to be the sum of nitric oxide and nitrogen dioxide.
NO — nitric oxide is the major oxide of nitrogen produced by combustion. It is rapidly oxidized to nitrogen dioxide in the atmosphere.
NO2 — nitrogen dioxide is the most abundant of the oxides of nitrogen in the atmosphere. It is a reddish-brown gas. The Alberta guidelines of a 1-hour average concentration of 210 ppb, a 24-hour average concentration of 110 ppb, and an annual average concentration of 30 ppb, are based on the prevention of human effects.
O3 — ozone at ground level is generated from emmisions of NOx and hydrocarbons. At high concentrations it may contribute to crop damage and cause respiratory problems. The Alberta guideline for ozone is 82 ppb for a 1-hour average. In the stratosphere it protects the earth from excessive ultraviolet radiation.
pH — the measurement of the degree of acidity on a scale of 1 to 14. One in very acidic, 7 is neutral and 14 is very alkaline. The natural pH of precipitation in the absence of pollution is thought to be 5.6.
PM10 — particles less than 10 micrometer in diameter, small enough to be inhaled but do not reach the lungs.
PM2.5 — particles less that 2.5 micrometer in diameter, small enough to be inhaled and may reach the lungs. Concentrations greater than 20 µg/m3 are thought to adversely affect pulmonary function.
SO2 — sulphur dioxide is formed during the processing and combustion of fossil fuels containing sulphur. It is a colourless gas with a pungent odour, and can be detected by taste and odour at concentrations as low as 300 ppb. Historically SO2 is the main component of acid rain.
Target Load — the maximum level of acidic atmospheric deposition, that affords long-term protection from adverse ecological consequences, and that is practically and politically achievable.
VOCs — volatile organic compounds can be emitted naturally or as by-products of industrial processes. Examples are terpenes produced by forests, ethylene from industrial and natural sources, and chloroform from industry.
Volume-weighted pH — the average pH of precipitation throughout the year when the volume of rainfall and the H+ concentration of each precipitation sample is considered.
Alberta guideline — concentration value adopted by the Province of Alberta with the intention of preventing deterioration of air quality. Guidelines for SO2, NO2, O3 and several other pollutants are based on the prevention of adverse human health and vegetation effects. Guidelines may be for 1 hour, 24 hours, or 1-year average concentrations.
Ambient air quality — the concetration of pollutants in the ambient air. Generally the concentrations of gases or particles to which the general population would be exposed to, as opposed to the concentration of pollutants emitted by a specific source.
Average annual concentration — the sum of the 1-hour average concentration measurements for the year divided by the number of hours that measurments were made within that year. It can be compared against the recommended guideline for the same period to assess absolute air quality or against other year's data to assess improvement or degredation of air quality in the same air.