Ambient Air Monitoring

There is a monitor set up in the Town of Pictou that is owned and operated by the Nova Scotia Environment to test the ambient air. This means the outdoor air.  Ambient air quality reflects the releases of impurities from both human activity and natural sources, as well as the effects of factors such as temperature, sunlight, air pressure, humidity, wind, rain, and landscape.

Contaminants are often measured in extremely small concentrations, in "parts per million" (ppm) - think of one drop in a bathtub - or even in "parts per billion" (ppb).  Not surprisingly, the monitoring unit needs regular maintenance and calibration or adjustment to produce the accurate results needed. The units themselves are costly to purchase and maintain.

There is an accessible Link to the Nova Scotia Environment Ambient Air Quality Data website (  The Town of Pictou air station can be found in the Northern air zone.

Objectives for the measured parameters can be found in the following link to the Nova Scotia Air Quality Regulations (N.S. Reg. 28/2005).

Monitored Pollutants


Ground-level Ozone

What is ozone?

O3 is a colourless, odourless gas at ambient concentrations and is a major component of smog.

What are the sources of ozone?

Ground-level ozone is not emitted directly into the atmosphere.  It results from photochemical reactions between oxides of nitrogen (NOx) and volatile organic compounds (VOCs) in the presence of sunlight.  Most of Nova Scotia’s ozone is carried here by air masses originating in the United States and central Canada.

 Fine Particulate Matter

What is fine particulate matter?

Particulate matter is characterized according to size - mainly because of the different health effects associated with particles of different diameters. Fine particulate matter are tiny (invisible) airborne specks of solid or liquid material (e.g., dust & soot). It is generated by natural sources (e.g. wind-blown dust and forest fires), and through fuel burning (especially fossil fuels and wood). Fine particulate matter is particulate matter that is 2.5 microns in diameter and less. It is also known as PM2.5 or respirable particles because it penetrates the respiratory system further than larger particles.

What are the sources of fine particulate matter?

PM2.5 material is emitted directly to air from cars, trucks, home firewood-burning, industry, forest fires, wind-blown dust and waste burning. Significant amounts of PM2.5 are carried into Nova Scotia from the U.S.

Oxides of Nitrogen (NO2, NO and NOx)

What are Oxides of Nitrogen (NO2, NO and NOx)?

Oxides of nitrogen (NOx) are the total of nitrogen dioxide (NO2) and nitric oxide (NO). During high temperature combustion, as in the burning of natural gas, coal, oil and gasoline, atmospheric nitrogen may combine with molecular oxygen to form NO. NO is colourless and odourless. Most NO in the ambient air will react with O3 to form NO2. NO2 is a reddish-brown gas with a pungent odour and is partially responsible for the brown haze observed near large cities.

What are the sources?

All combustion in air produces oxides of nitrogen (NOx), of which NO2 is a major product. NOx is generated through combustion, especially motor vehicle exhaust and fossil fuel burning electrical power generation. Smaller sources of NOx include natural gas combustion, heating fuel combustion, and forest fires.

 Sulphur Dioxide (SO2)

What is sulphur dioxide?

SO2 is a colourless gas. It smells like burnt matches. It can be oxidized to sulphur trioxide, which in the presence of water vapour is readily transformed to sulphuric acid mist. High concentrations of SO2 can damage plants, and corrode metals. It can irritate the eyes, throat, and lungs. It also contributes to acid rain, which impacts sensitive lakes and rivers.

What are the sources of SO2?

It is formed from the sulphur contained in raw materials such as coal, oil and metal-containing ores during combustion and refining processes.

Total Reduced Sulphur Compounds (TRS)

What are total reduced sulphur compounds?

TRS compounds produce offensive odours similar to rotten eggs or cabbage.

What are the sources of TRS?

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

Wind Direction

What is it?

Wind direction indicates the direction from which the wind is originating. It uses a 360° (compass) scale wherein 0° (or 360°) indicates a north to south wind direction, 90° indicates east to west, etc.). Wind direction is a meteorological (weather) parameter that allows us to better understand the behavior and impacts of air pollutants.

What does it do?

Collecting wind direction information allows us to infer the sources of pollutants associated with the ambient levels that are detected using other monitors. This can be helpful when trying to discern between impacts from industrial sources versus natural pollution sources, or to identify one source of impacts from several candidates.

Northern Pulp Ambient Air Stations

Northern Pulp operates two ambient air station located in Greenhill and Pictou Landing.  These two stations measure Total Suspended Particulates (TSP) . The TSP monitoring is conducted according to the Environment Canada National Air Pollutant Survey (NAPS) schedule with samples collected once every six days.   The NPNS TSP data for 2017 year-to-date is shown graphically below:



Total Suspended Particulates (TSP)

What are Total Suspended Particulates (TSP)?

Tiny particles of solid material or liquid aerosols, defined collectively as particulates, are present in the air, and at high concentrations, may become an air pollution concern. TSP range in size from 0.001 to 500 micrometres (for reference, a human hair is about 70 micrometres in diameter) and, depending on their size and other properties, may remain suspended in the air for a few seconds or indefinitely.

Suspended particles may result from a variety of natural and human sources. These sources include vehicle exhaust emissions, industrial emission sources, soil, road dust, dust resulting from other human activities (i.e. agriculture), smoke from forest fires and smoke from recreational sources (e.g. campfires and fireplaces).

Monitoring Method

TSP are measured by the high volume sampler. The sampler consists of a vacuum system and filter housed in a shelter and operates on the same principle as a vacuum cleaner. The particulate matter in the atmosphere is collected by drawing a known volume of air through a pre-weighed filter for a 24-hour period every sixth day according to the NAPS monitoring schedule. The filter is then re-weighed to determine the mass of the particles collected.


Objectives for TSP are: