The Canadian Air and Precipitation Monitoring Network (CAPMoN)

The Canadian Air and Precipitation Monitoring Network (CAPMoN), operated by Environment Canada, is designed to study the regional patterns and trends of atmospheric pollutants such as acid rain, smog, particulate matter and mercury, in both air and precipitation. The network began operating in 1983. CAPMoN updated and replaced two older networks known as the Canadian Network for Sampling Precipitation (CANSAP) and the Air and Precipitation Network (APN). The integration of APN as part of CAPMoN extended the data record as far back as 1978.

The Network was originally designed to make integrated measurements to help Canadians understand the sources and impacts of acid rain. This included integrated measurements of wet deposition (through rain or snow) and (inferential) dry deposition, as well as the ambient concentrations of acid-forming gases and particles. The regionally representative sites required to understand the sources and how long range transport impacts the Canadian environment have proven invaluable for a wide range of atmospheric issues.

As of 2010 there are 33 CAPMoN sites across Canada. The sites are predominantly located in central and eastern Canada but new sites are being developed in the west. There is a special site located at the Pennsylvania State University in the U.S. for comparison between CAPMoN and the United States National Atmospheric Deposition Program/National Trends Network (NADP/NTN). The Egbert site in Ontario fulfills a similar comparison function with two additional US networks: the Interagency Monitoring of Protected Visual Environments (IMPROVE) and Clean Air Status and Trends Network (CASTNET). CAPMoN is the core of the World Meteorological Organization Global Atmospheric Watch program's measurements in Canada.

CAPMoNwas designed as an atmospheric research network and its data must be of the highest possible quality. Quality control protocols are extensive and quality assurance is vigorous. Most data are publicly available but some are sequestered until peer reviewed papers are published or until data quality issues are resolved. Please refer to the Data and Products Section for information on how to access data on-line.


  • To determine spatial patterns and establish temporal trends of pollutants,
  • To provide information for atmospheric model evaluations and effects research (aquatic, terrestrial, building materials and health),
  • To ensure the compatibility of federal, provincial, U.S. and global measurements,
  • To study atmospheric processes,
  • To provide real-time information for air quality forecasts.

Measurements Summary:

More detail on CAPMoN Measurements is available in the Methods section.

  • Wet only precipitation
    24 hour integrated sample collected daily at 08:00 local standard time
    Chemical analyses for major ions
  • Non-size selective filter
    24 hour integrated sample collected daily at 08:00 local standard time
    Three stage filter pack. Analyses for major ions, sulphur dioxide and nitric acid
  • Mercury in precipitation
    7 day integrated sample collected at 08:00 local standard time each Tuesday
  • Continuous ground level ozone
    Hourly averages reported
  • Continuous Total Gaseous Mercury
    Hourly averages reported
  • Reactive Nitrogen
    Hourly averages reported
  • Course and PM2.5 mass
    24 hour integrated samples on a 1 day in 3 schedule