Air Quality Health Index (AQHI)
The Government of Canada has developed an Air Quality Health Index
(AQHI) and has piloted this index in selected cities across Canada starting in 2008. Daily AQHI readings for Hamilton are being piloted on
Environment Canada’s website. The Government of Canada’s new AQHI is calculated
in a different manner compared to the current Air Quality Index (AQI) that is
reported by the Ontario Ministry of the Environment. The MOE’s AQI currently takes
into account 6 pollutants: fine particulate matter (PM2.5,) nitrogen dioxide (NO2),
sulphur dioxide (SO2), carbon monoxide (CO), total reduced sulphur
(TRS) compounds and ground-level ozone (O3). The AQI value
is calculated based only on one of these six pollutants depending on which
pollutant has the highest value on its scale.
During the summer months when levels of ozone tend to be high, the
hourly AQI value (which is reported by the MOE) will usually be determined by
the concentration of ozone in the air.
In the spring and the fall, the
AQI level is driven by levels of PM2.5.
The AQHI pilot was launched in the
City of Hamilton in June 2011.
To see the AQHI for Hamilton visit: http://www.weatheroffice.gc.ca/airquality/pages/onaq-009_e.html
AQHI is calculated using a formula that combines the concentration and the
relative health impacts of three pollutants: ground-level ozone (O3),
particulate matter (PM2.5/PM10)
and nitrogen dioxide (NO2). According to the Government of Canada, sulphur
dioxide (SO2) and carbon monoxide (CO) were removed from
the formula as they were not associated with additional health risks once the
three pollutants were taken into account. It makes sense to use multiple pollutant contributors in determining
health effects impacts. This latter approach has been used in Clean Air
Hamilton’s health studies.
provincial and municipal governments collaborated in order to develop the AQHI
as a numeric tool that could be used by health professionals and the public to
determine the health risks related to air quality at a given time.
are directed at two
distinct populations – the “at risk” population and the general population.
The “at risk” population includes individuals at increased risk due to age or a
variety of conditions; these include young children, the elderly, people with
existing respiratory conditions (e.g., asthma, chronic obstructive pulmonary
disease (COPD), including bronchitis, emphysema and lung cancer) and people
with existing cardiovascular conditions (e.g., angina, previous heart attack,
congestive heart failure, arrhythmia or irregular heartbeat). The ‘general population’ includes all
other individuals who do not fall under the “at risk” population (Environment Canada, 2010).
in the “at risk” category are encouraged to monitor the AQHI more regularly
since they are more sensitive to air pollution.
These individuals are encouraged to develop their own self-calibration
points on the AQHI scale. Most people
understand how to use temperature, wind chill, UV Index and Humidex
values prior to going outdoors and to make decisions based on these
parameters. The AQHI value is another
factor that individuals will need to calibrate themselves to in the near
For more information on the Air Quality Health Index (AQHI) visit:
Hamilton Public Health
Services - http://www.hamilton.ca/HealthandSocialServices/PublicHealth/AirQualityHealthIndexInfo.htm
Environment Canada - http://www.ec.gc.ca/cas-aqhi/default.asp?lang=En&n=CB0ADB16-1