Air Quality Monitoring Programs

SESAA began data collection with a passive monitoring program in June of 2006. The program will monitor nitrogen dioxide, sulphur dioxide, hydrogen sulphide, ground level ozone, and fine particulate levels throughout southeast Saskatchewan. A continuous monitoring program was added in the spring of 2010. Continuous monitoring equipment provides nearly instantaneous measurements of ambient concentrations for several pollutants. Continuous sampling involves drawing air through a commercial analyzer calibrated to produce an output that is proportional to the ambient pollutant concentration.

What We Monitor

Ambient air is a complex mix of substances in the gaseous, liquid, and particulate (solid) phases. These substances may occur naturally, originate from anthropogenic (human-related) activities, or result from interactions between substances released from one or both of these sources.

SESAA currently measures nitrogen dioxide, sulphur dioxide, hydrogen sulphide, ground level ozone and fine particulate levels in the ambient air.



Nitrogen dioxide

Nitrogen dioxide (NO2) is formed when nitric oxide (NO) reacts with ozone in ambient air. NO is released during high temperature combustion processes when nitrogen present in hydrocarbon fuel and combustion air reacts with oxygen in combustion air. Collectively, NO and NO2 are referred to as oxides of nitrogen (NOx). Like SO2, NO2 may also react with water vapour in the air to form acidic compounds. NO2 and its acid products can cause adverse respiratory effects in people and animals, contribute to acid rain, and damage vegetation and buildings. The major emission sources of NOx in Canada are transportation, fossil-fuelled electric power plants, and the upstream oil and gas industry.

The Saskatchewan Ministry of Environment regulates ambient air concentration for nitrogen dioxide. Saskatchewan’s Ambient Air Quality Standards for nitrogen dioxide NO2 are:

1-hour Average

212 ppb

Annual Average

53 ppb



Sulphur Dioxide

Sulphur dioxide (SO2) is formed from burning of materials such as coal, fuel oils, and metallic ores. SO2 in the air may also react with water vapour to form acidic compounds and particulates. SO2 may cause or aggravate respiratory conditions in people and wildlife, contribute to acid rain formation, contribute to urban smog, and damage vegetation. In Canada, the major sources of SO2 are metal smelters, fossil fuel-fired power plants, transportation, upstream oil and gas, and other industrial facilities.

Saskatchewan’s Ambient Air Quality Standards for sulphur dioxide SO2 are:

1-hour Average

172 ppb

24-hour Average

57 ppb

Annual Average

11 ppb (annual arithmetic average)



Hydrogen Sulphide

Hydrogen sulphide is a colourless gas with a characteristic “rotten egg” odour. It occurs naturally in crude oil, natural gas, volcanic gases, and hot springs. It is produced in industrial activities such as natural gas and petroleum production, tanneries, wastewater treatment, kraft paper mills, rayon textile manufacturing, and tar and asphalt manufacturing. Hydrogen sulphide is an acutely toxic gas at high levels. Exposure to hydrogen sulphide can irritate the eyes, nose, throat, and lungs and can cause serious health effects, including death.

Saskatchewan’s Ambient Air Quality Standards for hydrogen sulphide H2S are:

1-hour Average

10.8 ppb

24-hour Average

3.6 ppb



Ground Level Ozone

Ground-level ozone (O3) is a secondary pollutant (i.e., it is not directly emitted by sources). It is formed through a series of photochemical reactions between NOx and volatile organic compounds (VOCs). O3 has been linked with aggravation of respiratory illnesses, contributing to urban smog, and damaging vegetation. The major emission sources of NOx in Canada are transportation, fossil-fuelled electric power plants, and the upstream oil and gas industry. Major sources of VOCs can be natural (vegetation) and human-related (motor vehicles, petroleum and chemical industries, other combustion processes, and evaporation of solvents and fuels). Ground-level ozone may also occur naturally from movement of stratospheric ozone downward into the troposphere (ground-level layer of the atmosphere).

Saskatchewan’s Ambient Air Quality Standards for ozone O3 are:

1-hour Average

82 ppb

8-hour Average

65 ppb (Canada-Wide Standard – the achievement statistics is based on the fourth highest measurement annually averaged over three consecutive years)



Fine Particulate

Ambient particulate matter consists of a mixture of particles of varying size and chemical composition. Particles that are less than 2.5 micrometers in diameter (PM2.5) can be trapped in the airways and lungs and is believed to cause adverse health effects. Fine particles (PM2.5) also reduce visibility and can contribute to acidification of soils.

PM2.5 size particles are formed from gases released to the atmosphere by combustion processes such as from motor vehicles, power plants, gas processing plants, compressor stations, household heating, and forest fires.


Influence of Meteorology

Air quality depends on the rate that pollutants are emitted to the atmosphere and the rate at which these pollutants are dispersed away from the sources. Air pollution transport and dispersion are influenced by wind speed and direction, the temperature structure of the atmosphere and changes in these elements induced by local topography.

Precipitation may remove pollutants from the atmosphere, depositing them on soils and vegetation. Rates of deposition of pollutant gases are highest when vegetation and soils are wet. Vegetation is more susceptible to damage during periods of highest growth.

Monitoring Program

Meteorlogical parameters measured in support of the air quality monitoring program are:

  • wind speed and direction
  • temperature
  • relative humidity
  • air pressure