Air Quality Health Index
Air Quality Health Index or AQHI is a scale designed to help understand the impact of air quality on health. It is a health protection tool used to make decisions to reduce short-term exposure to air pollution by adjusting activity levels during increased levels of air pollution. The Air Quality Health Index also provides advice on how to improve air quality by proposing behavioral change to reduce the environmental footprint. This index pays particular attention to people who are sensitive to air pollution. It provides them with advice on how to protect their health during air quality levels associated with low, moderate, high and very high health risks.
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[edit] The AQHI communicates four primary things
- It measures the air quality in relation to your health on a scale from 1 to 10. The higher the number, the greater the health risk associated with the air quality. When the amount of air pollution is very high, the number will be reported as 10+.
- A category that describes the level of health risk associated with the index reading (e.g. Low, Moderate, High, or Very High Health Risk).
- Health messages customized to each category for both the general population and the ‘at risk’ population.
- Current hourly AQHI readings and maximum forecasted values for today, tonight and tomorrow.
[edit] The AQHI
The Air Quality Health Index provides a number from 1 to 10+ to indicate the level of health risk associated with local air quality. Occasionally, when the amount of air pollution is abnormally high, the number may exceed 10. The AQHI provides a local air quality current value as well as a local air quality maximums forecast for today, tonight and tomorrow and provides associated health advice.
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | + |
| Risk: | Low (1-3) | Moderate (4-6) | High (7-10) | Very high (above 10) |
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.
| Health
Risk | Air Quality
Health Index | Health Messages | |||||
|---|---|---|---|---|---|---|---|
| At Risk population | General Population | ||||||
| Low | 1-3 | Enjoy your usual outdoor activities. | Ideal air quality for outdoor activities | ||||
| Moderate | 4-6 | Consider reducing or rescheduling strenuous activities outdoors
if you are experiencing symptoms. | No need to modify your usual outdoor activities unless you experience
symptoms such as coughing and throat irritation. | ||||
| High | 7-10 | Reduce or reschedule strenuous activities outdoors. Children and
the elderly should also take it easy. | Consider reducing or rescheduling strenuous activities outdoors if you
experience symptoms such as coughing and throat irritation. | ||||
| Very high | Above 10 | Avoid strenuous activities outdoors. Children and the elderly
should also avoid outdoor physical exertion. | Reduce or reschedule strenuous activities outdoors, especially if you experience
symptoms such as coughing and throat irritation. | ||||
[edit] How is the AQHI calculated?
The AQHI is calculated based on the relative risks of a combination of common air pollutants which are known to harm human health. These pollutants include:
- Ozone (O3) at ground level,
- Particulate Matter (PM2.5/PM10) and
- Nitrogen Dioxide (NO2).
[edit] Who is at Risk
The AQHI is aimed towards two populations: 1. The “general” population; and 2. The “at-risk” populations. The later consists of children, the elderly and people with existing respiratory or cardiovascular conditions, such as those with asthma, and people suffering from diabetes, heart disease or lung disease.
Children are more vulnerable to air pollution: they have less-developed respiratory and defense systems. Because of their size, they inhale more air per kilogram of body weight than adults. Their elevated metabolic rate and young defense systems make them more susceptible to air pollution.
Seniors are also at a higher risk because of the weakening of the heart, lungs and immune system and increased likelihood of health problems such as heart and lung disease.
Exposure to air pollutants can cause a range of symptoms. People with lung or heart disease may experience increased frequency and/or severity of symptoms, and increased medication requirements. It is recommended that those susceptive should take greater precautions.
[edit] AQHI and Lifestyle
Environment Canada recommends looking for outdoor air quality by checking the AQHI in your community 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. Seniors, parents, those with asthma, and people suffering from diabetes, heart or lung disease, can use the AQHI to assess the immediate risk air pollution poses on their health and take steps to lessen that risk. The AQHI is also recommended for healthy, fit and active people to consult to decide when it is best to exercise or work outdoor.
The best way for someone to use the AQHI is to regularly check the current index value, to pay attention to personal symptoms and self-calibrate to the reported current AQHI value. For example, if symptoms are experienced when the index is a 6, then precaution should be taken when the index is at a 6 or higher by following the corresponding health messages. 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.
