Monitoring the environment

Incident air monitoring timeline – description


  1. Incident begins
  2. EPA gets the call
  3. EPA assesses monitoring sites
  4. EPA staff collect IAM (incident air monitoring) equipment
  5. EPA travels to monitoring locations and sets up
  6. Monitors must collect at least 45 minutes of data*
  7. Air quality information is shown on EPA AirWatch web page
  8. EPA continues monitoring until pollution levels drop

From EPA getting the call till the monitors have collected at least 45 minutes of data takes 24 hours or less.

* Air monitors are programmed to calculate average pollution levels over a one-hour period. This is so the data can be compared with relevant air quality standards. We need at least 45 minutes of data to be able to calculate a one-hour average.

** From the time EPA begins collecting air quality data, it can take up to 2.5 hours for the first data to appear publicly on the EPA AirWatch website. This is because:

  • we need at least 45 minutes of data before we can calculate a one-hour average
  • the data for a one-hour period (e.g., 1–2pm) is shown on the website up to 45 minutes later (e.g., 2.45 pm). This lag is necessary to ensure our monitoring instruments have time to send their readings through the network and for EPA to check the instruments are working correctly.

Page last updated on 23 May 2017