Understanding Complex Data: Ambient Air Quality


We are all responsible for taking care of our air. Nova Scotia Environment (NSE) strives to monitor and protect our outdoor air quality through regulations and programs to reduce pollutants that lead to issues like smog, acid rain, climate change, and the thinning ozone layer. Poor air quality can affect our health, lead to increased health care costs and also affect natural resources.

About the Ambient Air Quality Unit

Nova Scotia Environment’s (NSE) Air Quality Unit supports and promotes the Protection, Enhancement and Prudent use of Nova Scotia’s air resources. The Unit's functions are to
  • Monitor, analyze and report on ambient air quality a via network of stations
  • Regulate air emissions, ambient air quality, and the use of ozone depleting substances (ODS) through Air Quality and Ozone Layer Protection regulations
  • Develop and implement policies and educational tools to promote and protect good air quality
  • Manage the industrial air emissions fees program

Monitoring and Measuring Air Quality

Nova Scotia Environment monitors for a variety of air pollutants at numerous ambient air quality stations, in four air zones across the Province. The Province’s air quality network is part of a larger Canada-wide air pollution monitoring program called the National Air Pollution Surveillance (NAPS) Program. There are currently seven NAPS monitoring sites using 33 instruments in communities across Nova Scotia, including Aylesford Mountain, Halifax, Kentville, Lake Major, Pictou, Port Hawkesbury, and Sydney.
A wide range of air monitoring equipment and techniques are used to accurately assess outdoor or “ambient” air quality conditions in Nova Scotia communities. NSE uses continuous gas analyzers to monitor Carbon Monoxide, Nitrogen Oxides, Ozone, Sulfur Dioxide, and Total Reduced Sulphur Compounds, and particulate samplers to monitor particulate matter less than 2.5 microns in size, each hour. Real-time, unvalidated data is continuously uploaded to NSE’s Air Data Website and is shared with Environment and Climate Change Canada (ECCC) to inform the Air Quality Health Index. The air quality analyzers are continuously operated, unless a monitor is removed for maintenance, repair, or calibration. Monitors are checked and calibrated and data is reviewed and validated on a regular basis. NSE also collects filter samples of particulate matter in downtown Halifax once every 3-days over a 24-hr period which are analyzed at the ECCC lab in Ottawa for a variety of chemical compounds.  Volatile Organic Compounds (VOCs) are measured at the same location once every 6 days over a 24-hr period. The filter sample and VOC data can be found on ECCC's NAPS Data Products website.
The Government of Nova Scotia has committed to participating in and to adhere to the national Air Quality Management System (AQMS). This commitment includes a requirement to report how the Province’s air pollution levels in four air zones compare to the Canadian Ambient Air Quality Standards (CAAQS) each calendar year. This comparison is illustrated in the form of annual air zone reports. Each report outlines the Province’s CAAQS achievement results over a three-year period. The most recent Provincial air zone report is available to view and download.
Long-term data from NSE’s ambient air quality monitoring network can help illustrate pollutant trends and the effectiveness of air regulations. The data from this network also supports many Provincial, National, and International programs, such as:
  • Environmental Goals and Sustainable Prosperity Act
  • NAPS Canada-Wide Air Quality Database
  • Canadian Ambient Air Quality Standards
  • Air Quality Health Index (AQHI)
  • Canada-United States Air Quality Agreement

Nova Scotia's  Four Air Zones

Nova Scotia is divided into four air zones that have shared terrain, meteorology and other natural factors that interact with air pollutant emissions to influence ambient air quality in the area.
Data are collected from ambient air monitoring stations in each air zone.
NSE’s air quality program administrators use an air zone management framework to help determine what management actions may be best suited to each air zone
  1. Western Air Zone - Annapolis, Digby, Kings, Lunenburg, Queens, Shelburne and Yarmouth Counties
  2. Central - Halifax and Hants Counties
  3. Northern Air Zone - Antigonish, Colchester, Cumberland, Guysborough and Pictou Counties
  4. Eastern Air Zone - Cape Breton, Inverness, Richmond and Victoria Counties
Air Quality Stations are located around the province in the following areas:
  • Aylesford
  • Dartmouth
  • Halifax
  • Kentville
  • Pictou
  • Port Hawkesbury
  • Sydney

The Air Quality Team monitors and analyzes several pollutants including:
  • Carbon Monoxide (CO): A poisonous, colourless, odourless, and tasteless gas, generated through combustion processes. CO is very toxic to humans at high concentrations.
  • Nitrogen Oxides (NOx): Nitrogen oxides include the gases nitric oxide (NO) and nitrogen dioxide (NO2). NOx emissions come from vehicle and ship transportation, as well as coal fired electric power generation. NOx combines with atmospheric water to form Nitric Acid - which results in acid precipitation. In the presence of sunlight, NOx reacts with volatile organic compounds to form ground-level ozone, a component of smog
  • Ozone (O3): An invisible and odourless gas. While ozone in the upper atmosphere helps to protects us from the sun's harmful ultraviolet rays, ground level ozone is harmful. Ground level ozone is the main component of smog and is formed by chemical reactions in the presence of sunlight and heat
  • Particulate Matter (PM2.5): Fine particles (PM2.5) of solid or liquid material are smaller than 2.5 micrometers in diameter and can be inhaled deeper into the lungs and have many known health impacts.
  • Sulphur Dioxide (SO2): Sulphur dioxide is a noxious gas released from burning coal and other fuels that contributes to the formation of acid rain and particulate matter pollution.
  • Total Reduced Sulphur (TRS): A gaseous mixture of sulphur compounds, in a reduced form that produce odours similar to rotten eggs. TRS includes H2S, mercaptans, dimethyl sulphide and other sulphur compounds (with the exception of SO2). TRS comes from industrial sources such as refineries, natural gas plants, sewage treatment facilities, pulp and paper plants, and natural sources such as swamps and lakes.
Measurements of PM2.5, O3, and NO2 are used to report the Air Quality Health Index (AQHI) which is available on Environment Canada's Air Quality Health Index website and on the Weather Network. Environment Canada updates the current AQHI each hour and provides forecasted maximum values twice daily. The AQHI is a public information tool available to assist individuals in making short-term decisions about adjusting their activities to limit exposure to air pollution. The AQHI is based on raw data which has not been validated, so it is not used to determine trends or for other detailed analysis of ambient air quality.
Met One BAM (PM2.5) monitor (left), Thermo Dichotomous Samplers (back and right) and a Met One Speciation Sampler (front) on the roof of the Johnston building in downtown Halifax.
Particulate and gas monitors or analyzers in a typical NSE air quality station. From left to right: Teledyne-API O3 analyzer, Teledyne-API NO, NO2, NOx analyzer, Met One BAM (PM2.5) 1020, Teledyne-API SO2 analyzer.

Ambient Air Quality Data on the Nova Scotia Open Data Portal

Nova Scotia Environment has released several ambient air quality datasets on the portal. The table below contains data recorded for Ambient Fine Particulate Matter (PM2.5) for Pictou and is just one one example of the data released by Nova Scotia Environment on the Open Data Portal. The charts below depict monthly averages and maximums for Fine Particulate Matter (PM2.5) for Pictou and Port Hawkesbury and monthly averages and maximums for Ozone for Aylesford and Halifax. 
Nova Scotia Provincial Ambient Fine Particulate Matter (PM2.5) Hourly Data Pictou BAM
Nova Scotia Provincial Ambient Fine Particulate Matter (PM2.5) Pictou BAM Recorded Monthly Average
Nova Scotia Provincial Ambient Port Hawkesbury Fine Particulate Matter (PM2.5) BAM Recorded Monthly Average
Nova Scotia Provincial Ambient Fine Particulate Matter (PM2.5) Pictou BAM Monthly Recorded Maximum Average
Nova Scotia Provincial Ambient Fine Particulate Matter (PM2.5) Port Hawkesbury BAM Monthly Recorded Maximum Average
Nova Scotia Provincial Ambient Ground-level Ozone (O3) Aylesford Recorded Monthly Average
Nova Scotia Provincial Ambient Ground-level Ozone (O3) Halifax Recorded Monthly Average      
Nova Scotia Provincial Ambient Ground-level Ozone (O3) Aylesford Monthly Recorded Maximum Average
Nova Scotia Provincial Ambient Ground-level Ozone (O3) Halifax Monthly Recorded Maximum Average

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