SMOG

• What is smog?
• What causes smog?
• Is smog bad for me?
• Who is most at risk?
• How can I protect myself?
• What can I do to help?
• How can I tell if it’s smoggy?
• What is the Ministry of the Environment doing about smog?
• Where can I get more information?
• If you are a business, industry or emitter, please check our Resources for Business section for important information that pertains to you.

What is smog?

Smog is a form of air pollution. It is a complex mixture of air pollutants that is sometimes visible in the air. So when we hear the word smog, many of us picture the chemical "soup" that often appears as a brownish-yellow haze over cities. But smog isn't always visible. It's a mixture of air pollutants, including gases and particles that are too small to see. Smog is a mixture of many pollutants, but the two main ingredients of smog are ground-level ozone (O₃) and particulate matter(PM).

Smog can form in almost any climate where industries or cities release large amounts of air pollution. However, it is worse during periods of warmer, sunnier weather.

Return to top

What causes smog?

The contaminants that create smog are released during the burning of fossil fuels in our vehicles, power plants, factory boilers and homes. They are also released by industrial processes, the evaporation of liquid fuels and the use of solvents and other volatile products such as oil-based paints.  Pollutants like nitrogen oxides, sulphur dioxide and volatile organic compounds mix with sunlight to form ground-level ozone. 

Most of Ontario's smog problems are caused by a combination of local emissions and pollutants carried by the wind from pollution sources in the United States. More than half of our smog problem comes from south of the border.

Return to top

Is smog bad for me?

Smog is a problem in a number of Ontario cities and poses a threat to human health. Since smog travels with the wind, both urban and rural areas can experience smoggy days. Overall, smog is harmful to both the respiratory (lungs) and cardiovascular (heart) systems. It aggravates heart problems, bronchitis, asthma, and other lung problems. Smog reduces lung function even in healthy people. Even at low levels, ground level ozone and fine particulate matter are harmful. There are no "safe" levels of smog.

Ground-level ozone is especially harmful for senior citizens, children, and people with heart and lung conditions such as emphysema, bronchitis, and asthma. It can inflame breathing passages, decreasing the lung's working capacity, and causing shortness of breath, pain when inhaling deeply, wheezing, and coughing. It can cause eye and nose irritation and it dries out the protective membranes of the nose and throat and interferes with the body's ability to fight infection, increasing susceptibility to illness.

When the amount of ground-level ozone increases, so do then number of emergency room visits and hospital admissions. It can even cause premature death.

Particulate matter (PM) is a fine dust that is created when we burn fossil fuels to run our vehicles and create electricity.  Quarries that mine gravel to make concrete and cement also produce PM.

The smaller the particle, the deeper it can be inhaled. Larger particles usually settle in the mouth and nose, while fine particles can penetrate into the lungs. Once in the lungs PM can decrease the lungs' working capacity and aggravate respiratory symptoms such as wheezing, coughing and shortness of breath.

When there is more particulate matter in the air, death rates are higher.

Return to top

Who is most at risk?

Although smog affects each and every one of us, it is especially harmful to:

Children: Children's lungs are still developing. Children have smaller airways and breathe more rapidly than adults. They also tend to spend more time outdoors in the summer. All these factors increase their risk of inhaling more polluted air.

Asthma sufferers: People with asthma already have poor lung function to begin with. Ground-level ozone and particulates can cause additional inflammation in the lungs that can aggravate symptoms or trigger an asthma attack.

Seniors: Seniors are at higher risk not only because they are more likely to have a pre-existing health condition. Smog is particularly dangerous for seniors who suffer from asthma, chronic obstructive pulmonary disease, emphysema, bronchitis, heart disease, or hardened arteries. Seniors who smoke or are especially active outdoors need to exercise special caution.

People who work or exercise outdoors: While exercising, you breathe harder and mostly through the mouth, so the air doesn't get the filtering provided by the nose, which means more polluted air gets through. You might feel you are doing your body good by jogging down a congested urban street, but you are actually putting your lungs at a greater risk.

Other people who need to be careful on smoggy days include people with allergies, pregnant women, smokers, and people with lung and heart disease.

Return to top

How can I protect myself?

• Be aware. Listen to smog forecasts and consider ways to modify daily activities accordingly (e.g., car pool, take transit, work from home, group errands together).
• Limit your exposure. On days when ozone levels are high, you have a greater likelihood of being harmed by smog if you stay outdoors for longer periods and if you perform strenuous activity.
• Stay hydrated. Hot temperature and high humidity often correspond with high smog levels. This makes it important to stay in the shade and drink lots of fluids to stay hydrated, especially before, during, and after exercise.
• Consider exercising indoors in an air-conditioned environment. Avoid exercise outdoors, especially from mid-morning to early evening, when smog levels are higher.
• Protect those at higher risk of health problems. Pay special attention to children, seniors, asthmatics, those with heart problems and those who work outdoors.

Return to top

What can I do to help?

Smog-causing pollutants come from many sources including the burning of fossil fuels to run our vehicles and produce energy.  The easiest ways to reduce our contribution to smog are to use reduce our use of gas-powered vehicles and conserve our energy use.    

• When possible, use public transportation instead of your car. You could also walk or ride your bicycle, as long as smog levels are not too high.
• Look for alternatives to gas-powered machines and vehicles. Try a rowboat or sailboat instead of a motorboat or a push-type lawnmower instead of one that runs on gasoline.
• Consider fuel efficiency when you buy a vehicle. Keep all vehicles well maintained and tired properly inflated.
• Reduce energy use in your home. Learn more about alternative energy resources.
• Do not burn leaves, branches or other yard wastes.
• Consider joining a citizens' committee to advocate for cleaner air in your community.
• Spend time talking with your children about the importance of a sustainable lifestyle.

Saving Energy at Home: Did You Know…?

• A 15-watt energy-saving compact fluorescent light bulb produces about the same amount of light as a 60-watt incandescent bulb.
• If a household replaced just one incandescent 60-watt bulb with an energy saving bulb, over one year at eight hours a day it would save 130 kilowatt-hours (kWh) of electricity and reduce air emissions by up to 120 kg.
• An average 15-year-old refrigerator consumes more than twice as much energy (1067 kWh) as a modern Energy Star certified model (426 kWh) each year. Your old, inefficient refrigerator running in the basement for occasional refreshments costs the environment and could cost you $150 or more per year in electricity.
• An average Energy Star qualified front-loading washing machine consumes less than a third the energy (275 kWh per year) of an average top-loading washing machine (876 kWh per year).
• A standard clothes dryer consumes 900 kWh of energy per year, creating up to 840 kg of air pollution and greenhouse gases. If you were to hang-dry one-quarter of your laundry loads, you would reduce air pollution and greenhouse gases by up to 210 kg.
• The Ministry of Energy estimates that the average detached house with central air conditioning and electric water heating uses 1500 kWh/month. This means that the emissions from an average household’s monthly electricity consumption could weigh more than a compact car.
• If the average household cut its energy consumption by just six per cent, it would reduce annual greenhouse gas emissions by just over one tonne.
• Setting air conditioners up two degrees Celsius can save 100 kWh, which equals up to 100 kg of air pollution and greenhouse gases. During heating season, set a lower temperature for overnight or when you are away. A set-back of six degrees Celsius for eight hours daily could reduce your heating bill by 10 per cent, which means savings of $120 a year for the average Ontario family.

On the Road: Did You Know…?

• One poorly tuned vehicle can emit as much pollution as 20 properly tuned cars.
• The average total cost of driving one kilometre in Canada is 46 cents per person. On public transit, this cost drops to 12 cents.
• A well-maintained car runs better and pollutes less. Shut the engine off, even for short stops. One minute of idling uses more fuel than restarting your engine.
• Speeding is not only illegal, it also increases your car’s fuel consumption. At 120 km/h, your fuel consumption could be as much as 20 per cent higher than at 100 km/h.

Return to top

How can I tell if it’s smoggy?

The Air Quality Index, or AQI, is a rating of how clean the air is. It is issued by the Ministry of the Environment, which monitors our air quality every day. The AQI captures the following air pollutants:

1. carbon monoxide
2. nitrogen dioxide
3. ozone
4. respirable particulate matters (particles that can be inhaled)
5. sulphur dioxide
6. total reduced sulphur compounds

The AQI scale ranges from 0 to 100. Higher numbers mean higher health risks. A Smog Watch is issued when there is a 50% chance of a smog day within the next 3 days. When the AQI is expected to get higher than 50 in the next 24 hours, a Smog Alert (or Smog Advisory) is issued. To learn about AQI levels in your community, contact your provincial ministry of health.

Return to top

What is the Ministry of the Environment doing about smog?

• Ontario’s Plan for Clean Air
• Sector Compliance Branch
• Environmental Compliance Reports
• 24-hour Public Hotline
• Smog Alert - A Municipal Response Guide
• Sulphur-in-Gasoline
• Emissions Trading Registry
• Drive Clean

Return to top

Where can I get more information?

• Smog and Your Health
• Smog Advisory Today: Why should I care? Even healthy kids are vulnerable.
• Outdoor Activities: Smog Matters - Physical exercise and smog don’t mix. Protect your health when air quality is poor.
• Smog Advisory Today: Are seniors at risk? Protect yourself from the harmful effects of smog.
• Green Facts: Smog and Your Health 
• Green Facts: Ontario’s Air Quality Index   
• Green Facts: Ways to Reduce Your Contribution to Smog
• Ministry of the Environment – Air Quality Ontario
  

Return to top