Significantly, AQI values reflect air quality management objectives, which are based on the lowest achievable emissions rate, and not exclusively concern for human health.
The AQHI was created with a different goal - to report on the specific health risks posed by air pollution.
From air quality monitoring to health risk communication and community engagement, local partners are responsible for the vast majority of work related to AQHI implementation.
The AQHI has been rolled out across Canada and has replaced the AQI as the public face of air quality information.
Originally launched as a pilot project in the British Columbia Interior in 2005 followed by Nova Scotia in 2006 and Toronto in 2007,[2] as of 2016 it was implemented in 122 locations across Canada.
As it is now known that even low levels of air pollution can trigger discomfort for the sensitive population, the index has been developed as a continuum: The higher the number, the greater the health risk and need to take precautions.
The index describes the level of health risk associated with this number as 'low', 'moderate', 'high' or 'very high', and suggests steps that can be taken to reduce exposure.
[4] The formulation of the national AQHI is based on the observed relationship of nitrogen dioxide (NO2), ground-level ozone (O3) and fine particulate matter (PM2.5) with mortality from an analysis of several Canadian cities.
[6] When developing the AQHI, Health Canada's original analysis of health effects included five major air pollutants: airborne particulate matter, ozone, and nitrogen dioxide (NO2), as well as sulphur dioxide (SO2), and carbon monoxide (CO).
The measurement is based on the observed relationship of nitrogen dioxide (NO2), ground-level ozone (O3) and particulates (PM2.5) with mortality, from an analysis of several Canadian cities.
The national AQHI is based on three-hour average concentrations of ground-level ozone (O3), nitrogen dioxide (NO2), and fine particulate matter (PM2.5).
In order to meet these needs, the individual pollutant concentrations are compared to Alberta's Ambient Air Quality Objectives (AAQOs).
Their elevated metabolic rate and young defense systems make them more susceptible to air pollution.
[9] Environment Canada recommends looking for outdoor air quality by checking the AQHI before heading off to work or play as well as to use the forecasts to plan activities, whether over the next hour or the next day.
The AQHI is also recommended for healthy, fit and active people to consult to decide when it is best to exercise or work outdoor.
Then, when an individual knows what number triggers health symptoms, to get in the habit of checking the maximum forecast to plan activities ahead of time.