Small Sensors, Big Sensors: What’s the Difference? 

Small air sensors are ideal for residents to measure local air quality. They are relatively inexpensive, easy and fast to install, and many of them can be installed in a specific place to gather large amounts of data to provide a detailed look at air quality patterns in a particular community. Small sensors can also be deployed quickly in emergency situations if immediate and short-term air monitoring is needed. However, sensor performance, accuracy, life span, and ability to function in extreme weather conditions, can vary widely from sensor to sensor.

Metro Vancouver operates and maintains instruments to measure ambient air quality that are more sophisticated than small air sensors. These instruments, known as reference monitors, meet strict performance standards for air quality measurements.  


While more expensive and time-consuming to install and configure, the reference monitors housed in Metro Vancouver’s air monitoring stations collect comprehensive data that can be used to track long-term trends in air quality, summarized each year in an air quality monitoring report. Trends and annual snapshots of the region’s air quality help guide new policies to protect and improve our region’s air quality, and evaluate the effectiveness of existing policies.

Small Sensors vs. Reference Monitors

Small Sensors

​Advantages

Disadvantages

  • Small and portable
  • Inexpensive (usually less than $1000)
  • Easy to set up: some are usable “out of the box”, but others could require more time to configure the sensor
  • Can be used as educational or engagement tools
  • Data can be viewed on a smartphone app for some sensors
  • Wide range of options (pollutant measured, data interface, size, etc.) to suit various needs
  • Limited life span depending on the sensor, some could be as short as 2-3 years but the life span of small sensors is not yet well understood
  • Often not possible to be user-calibrated
  • No performance or design standards
  • Measurements of some air contaminants, such as particulate matter, can be affected by extreme temperatures or high humidity
  • Might not be weatherproof
  • Might have difficulty measuring very high or very low concentrations of air pollutants

Reference Monitors

​Advantages

​Disadvantages

Big Sensors
  • Meet strict performance standards to ensure accurate data
  • Can be calibrated if measurements begin to drift
  • Data is validated by trained staff to ensure accuracy, allowing the data to be used for regulatory purposes or policy decisions
  • Can last for 10+ years
  • Weatherproof: housed in temperature controlled buildings with a weatherproof inlet to measure outdoor air
  • Have internal systems to ensure changes in temperature or pressure do not affect the measurements


  • Large and heavy, usually fixed in one location
  • Expensive: tens of thousands of dollars
  • Lengthy set up procedure best suited for trained staff
  • Require regular maintenance by trained staff