Outdoor Air Quality

What is air pollution?

Air pollution is made up of toxic materials from human activities like driving, farming, industries and natural disasters like wildfires.

When levels are high enough it can harm our health and the environment. Some air pollution you can see like smog, and others you cannot see. Air pollution is worsened by the changing climate as it leads to more smog production. Air pollution also contributes to the changing climate by increasing the temperature and reducing the ozone layer.

What is smog?

Smog is a mixture of particles and gases that are toxic to our health. It usually consists of Ground level ozone and particulate matter. Smog is more common in the summer due to higher temperatures and more sunlight.  Smog occurs during the winter months due to more wood burning and vehicle use.

What are the types of air pollutants?

There are many things that pollute the air that we breathe. The more common air pollutants that pose a risk to our health are particulate matter, ground-level ozone, and other pollutants like nitrogen dioxide.

  • Ground level Ozone (O3): is a gas that has no odour or colour. It is made by a reaction between volatile organic compounds (VOCs), nitrogen oxides (NOX) and sunlight. Levels are highest from noon to early evening between the months of May and September. Both VOCs and NOX come from human activities (burning of fuels in vehicles, industries, power plants) and natural sources (hydrocarbons released by plants and soil).
  • Particulate Matter (PM2.5): is a mixture of liquid and solid particles in the air. This includes smoke, fumes, dust, pollen, aerosols, and ash. It may contain different things depending on the location, season and weather conditions. Fine particulate matter (PM2.5) is very small, so it can go much farther into the airways when we breathe making it more dangerous. It is given off directly from vehicles, industries, home wood fires, waste fires and forest fires.
  • Nitrogen Dioxide (NO2): is a reddish-brown gas that has a sour and irritating odour. It changes to nitric acid gas and toxic organic nitrates in the air. It plays a big role in the production of ground level ozone and higher fine particulate matter levels.

Air pollution is hard to avoid as we breathe air to survive.

Air pollution can cause many health problems or make current health problems worse.

How air pollution affects health?

The amount of pollutant in the air, length of time you are around it, your health status and genetics all play a part in how air pollution will affect your health. 

Air pollution may make it harder to breathe, cause throat or lung irritation, or produce new or worsening episodes of your current heart or lung conditions.

Everyone reacts differently to air pollution so it is important to be aware of your symptoms.

Negative health effects increase as air pollution worsens. Even a modest increase in pollution can cause more visits to the emergency department, hospital admissions and deaths. (Government of Canada, 2016).

Who’s at risk?

Air pollution affects us all, but those at a higher risk are:

  • People with current heart, lung or diabetic conditions
  • Infants and young children
  • Older adults/elderly
  • People who spend more time outdoors (for work, physical activity etc.)
  • Pregnant women

Consult your health care provider about your medical problems, and follow their advice to help protect your health.

What is the Air Quality Health Index (AQHI)?

The AQHI is a scale made for the public to help identify how the quality of air around you affects your health. This tool was made by environmental and health professionals to communicate what the health risks are. It provides tips for both at risk and general populations. The higher the score, the more risks there are to your health.

How is AQHI measured?

Ground level ozone, particulate matter and nitrogen dioxide are the more common air pollutants known to cause harm to human health that are used in calculating the AQHI score/risk.

There are two stations within Windsor-Essex County that measure AQHI: Windsor West and Windsor Downtown.

What is the scale for AQHI?

The AQHI is measured on a 1-10+ scale, and divided into four risk groups, as seen below.

Image of AQHI scale, indicating risk groups based on air quality

Government of Canada (2016).

Shown above:
  • Levels 1-3 = Low Risk
  • Levels 4-6 = Moderate Risk
  • Levels 7-10 = High Risk
  • Levels 10+ = Very High Risk

How can you use the AQHI to protect your health?

Health Risk


Health Messages

At Risk Population*

General Population



ENJOY your usual outdoor activities.

IDEAL air quality for outdoor activities.



CONSIDER reducing or rescheduling strenuous activities outdoors if you are experiencing symptoms.

NO NEED TO MODIFY your usual outdoor activities unless your experience symptoms such as coughing and throat irritation.



RESCHEDULE or REDUCE strenuous activities outdoors. Children and the elderly should take it easy.

CONSIDER reducing or rescheduling strenuous activities outdoors if your 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.

Government of Canada (2015).

*Those with heart or lung health problems are at a higher risk of complications. Follow your health care provider’s advice about exercise and how to manage your health problems during these times.

What is a Special Air Quality Statement (SAQS)?

When a high risk (7 or greater) AQHI score is likely to last for 1 or 2 hours, a SAQS is issued for the area. The purpose is to allow the public to take the proper safety measures as it relates to their health.

What is a Smog and Air Health Advisory (SAHA)?

When a high risk (7 or greater) AQHI is likely to last a minimum of 3 hours, a SAHA is issued for the area. The purpose is to alert those with breathing problems to reduce or avoid unnecessary exposure to smog. It also informs industries that are major producers of pollution in the area that they should consider reducing their emissions for a short period of time if possible.

How can you Protect Yourself, Your Family and the Environment?

  • Check the Air Quality Health Index for your area at the start of each day to help make decisions regarding your health.
  • Plan activities for earlier in the day before air pollutants are at a higher level.
  • Keep your medications like rescue inhalers on you.
  • Delay any outdoor activities until the AQHI level is lower.
  • Be aware of any symptoms you experience especially if you have heart or lung conditions, and seek medical attention if they worsen.
  • Avoid areas with heavy pollution like busy streets and industrial areas especially when the AQHI is higher.
  • Take public transportation, carpool, and when air quality is good walk or bike.
  • Reduce air conditioner use in the summer.
  • Avoid using the fireplace or wood-burning stove when possible during the winter.
  • Keep up to date on your vehicles routine care.

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