Airborne Pollutant Descriptions

Air issues such as smog and acid rain result from the presence of, and interactions between, a group of pollutants known as Criteria Air Contaminants (CAC) and some related pollutants. CAC are produced from a number of sources, including burning of fossil fuels, and it is because of these shared sources that CAC are grouped together. HAMN continually monitors several of these pollutants at various air monitoring sites located around the Hamilton industrial area. The pollutants monitored include sulphur dioxide (SO2), total reduced sulphur (TRS), nitrogen dioxide (NO2), nitric oxides (NO), oxides of nitrogen (NOx), and inhalable particulate matter (PM10).

Pollutants described on this page:
Sulphur Dioxide (SO₂)
TRS - Total Reduced Sulphur
Nitric Oxides (NO), Nitrogen Dioxide (NO₂), Oxides of Nitrogen (NO_x)
Inhalable Particulates (PM₁₀), Total Suspended Particulates (TSP)

What is sulphur dioxide?
Sulphur dioxide (SO₂) is a colourless gas, belonging to the family of gases called sulphur oxides (SO_x). SO₂ smells like burnt matches. Natural sources of sulphur dioxide include releases from volcanoes, oceans, biological decay and forest fires. The most important man-made sources of sulphur dioxide are fossil fuel combustion, smelting, manufacture of sulphuric acid, conversion of wood pulp to paper, incineration of refuse and production of elemental sulphur. Coal burning is the single largest man-made source of sulphur dioxide.

How do we measure SO₂?
U.V FLUORESCENCE: Absorption of ultraviolet radiation by SO₂ sulphur dioxide is followed by fluorescence at higher wavelengths. Ambient air is drawn through a cell where it is irradiated with ultraviolet light. The resulting fluorescence is detected by a photomultiplier tube. The amount of fluorescence is a measure of the sulphur dioxide concentration. SO₂ is measured continuously at the air monitoring stations.

Air quality standards
MOE: 1- hour AAQC (Ambient Air Quality Criteria) 250 ppb (parts per billion) or 690 µg/m3
MOE: 24- hour AAQC (Ambient Air Quality Criteria) 100 ppb (parts per billion) or 275 µg/m3
MOE: Annual AAQC (Ambient Air Quality Criteria) 20 ppb (parts per billion) or 55 µg/m3
Ontario's Ambient Air Quality Criteria

Links- more information on SO₂
http://www.airqualityontario.com/science/pollutants/sulphur.cfm
http://www.ec.gc.ca/cleanair-airpur/SOx-WSBBB2123F-1_En.htm

What are total reduced sulphur compounds?
The main compounds that make-up TRS are hydrogen sulphide, methyl mercaptan, dimethyl sulphide and dimethyl disulphide. Most studies examine this mixture. These compounds are odourous at low very concentrations and relate to rotten eggs smell.

Industrial sources of TRS include the steel industry, pulp and paper mills, refineries and sewage treatment facilities.

How do we measure TRS?
U.V FLUORESCENCE: Firstly, SO₂ is removed from the sample gas. The sample containing TRS enters a high temperature converter and is converted to SO₂. Absorption of ultraviolet radiation by SO₂ sulphur dioxide is followed by fluorescence at higher wavelengths. Ambient air is drawn through a cell where it is irradiated with ultraviolet light. The resulting fluorescence is detected by a photomultiplier tube. The amount of fluorescence is a measure of the sulphur dioxide concentration. TRS is measured continuously at the air monitoring stations.

Air quality standards
MOE: 1- hour Guideline, 27 ppb (parts per billion)
MOE: 24- hour AAQC (Ambient Air quality Criteria), 5 ppb (parts per billion) or 7 µg/m3
MOE: 1-hour RT (reporting threshold), 10ppb (parts per billion) or 13 µg/m3
Ontario's Ambient Air Quality Criteria

Links - more information on TRS
Ministry of the Environment - Total Reduced Sulphur Compounds

NO₂ is a reddish-brown gas with a pungent and irritating odour. It transforms in the air to form gaseous nitric acid and toxic organic nitrates. NO₂ also plays a major role in atmospheric reactions that produce ground-level ozone, a major component of smog.

Transportation, power generation, primary metal production and incineration are sources contributing to NO_x emissions.

How do we measure NO_x?
CHEMILUMINESCENCE: The analyser uses the principle of chemiluminescence detection. When two specific chemicals reacting together the resulting reaction will create a luminescence. Within the analyser when NO and Ozone react they produce a characteristic luminescence with an intensity proportional to the NO concentration. To measure NO₂, NO₂ must first be converted into NO before it can be measure by chemiluminescence detection method. This is done be using a high temperature (325 degrees C) NO₂ to NO converter. The analyser continuously measures and records NO, NO₂ and NO_x readings.

Air quality standards
MOE: 1- hour NO₂ AAQC (Ambient Air quality Criteria) 200 ppb (parts per billion) or 400 µg/m3
MOE: 24- hour AAQC (Ambient Air quality Criteria), 100 ppb (parts per billion) or 200 µg/m3
Ontario's Ambient Air Quality Criteria

Links- more information on NO_x
http://www.airqualityontario.com/science/pollutants/nitrogen.cfm
http://www.ec.gc.ca/cleanair-airpur/NOx-WS489FEE7D-1_En.htm

What is particulate matter?
Particulate matter (PM) consists of airborne particles in solid or liquid form. It includes aerosols, smoke, fumes, dust, ash and pollen. Particulate matter is characterized according to size - mainly because of the different health effects associated with particles of different diameters. Some particles are emitted directly into the atmosphere. Other particles result from gases that are transformed into particles through physical and chemical processes in the atmosphere.

Total Suspended Particulate (TSP) -airborne particulate matter with an upper size limit of approximately 100 micro metre (µm) in aerodynamic equivalent diameter. Particulate Matter <10 microns (PM₁₀) - also referred to inhalable particulates, are airborne particulate matter with a mass median diameter less than 10 µm. A variety of emission sources and meteorological conditions contribute to ambient PM₁₀. Particulate Matter < 2.5 microns (PM_2.5) – also referred to as respirable particulates are airborne particulate matter with a mass median diameter less than 2.5 µm.

How do we measure particulate matter (PM₁₀)?
TEOM-MASS CONCENTRATION: A TEOM (tapered element oscillating microbalance), is a micro weighing technology that provides true mass real-time measurements of particulate matter. The sampling head is outfitted with a PM₁₀ size selective inlet. A sampling filter is mounted on the microbalance, sample gas deposit particulates on the filter reducing the microbalance frequency. This reduced frequency is directly proportional to the amount of mass on the filter. A mass flow controller maintains the sampling flow to calculate the mass concentration in µg/m3.

BETA RADIATION: At the start of the sampling period, beta ray transmission is measured across a clean section of filter tape. This section of filter tape is then mechanically advanced to the sampling inlet. Particulate matter is then drawn into the sample inlet and deposited on the filter paper. At the completion of the sampling period, the filter tape is returned to its original location and the beta ray transmission is re-measured. The difference between the two measurements is used to determine, with exceptional accuracy, the particulate concentration. The sampling head is outfitted with a PM₁₀ size selective inlet.

Air quality standards
MOE: 24- hour PM10 AAQC (Ambient Air Quality Criteria) 50µg/m3 (micrograms per cubic metre)
Ontario's Ambient Air Quality Criteria

Links- more information on particulate matter
http://www.ec.gc.ca/cleanair-airpur/PM_2.5,10-WS2C68B45C-1_En.htm