Sky Watchers' Guide
Air Quality Supplement
Download Air Quality Supplement (PDF; 595 KB)
In this chapter
- What is Smog?
- Smog Behaviour
- Effects Of Pollution
- Air Quality Prediction
- What Can We Do To Reduce Pollution?
Air Pollution, Smog and Our Air Quality
Every living thing on earth needs air: plants, trees, animals, birds, humans and everything in between. The air we breathe is made up of different gases (78 percent nitrogen, 21 percent oxygen, 0.9 percent argon, 0.03 percent carbon dioxide and the remaining 0.07 percent a mixture of hydrogen, water, ozone, neon, helium, krypton, xenon and other trace components). In order for us to survive, we require oxygen (O2). In order for plants to survive, they need a different gas, called carbon dioxide (CO2). When we breathe, our lungs take in all the gases in the air around us. Thus it is important for the future of our planet, and the health of all living things, that we do what we can to reduce air pollution.
As you know, the air around you is invisible. You can't see yourself take in these gases. Most of the pollution in the air is also invisible. Sometimes, especially if you live in a large city, pollution concentrations can be high enough that you can actually see the pollution in the air. Pollution, whether visible or invisible, is also known as smog.
To illustrate to your students the difference between visible and invisible pollution, try Activity number 1
The term smog originally described a mixture of smoke and fog in the air. Now it is used to describe a mixture of pollutants. This mixture can often be seen as a brownish-yellow or greyish-white haze in the air. The two key components of smog are particulate matter (PM), also known as airborne particles, and ground-level ozone (O3). Other pollutants include sulfur dioxide (SO2), nitrogen oxides (NOx), carbon monoxide (CO), and hydrogen sulphide (H2S).
Fast Fact: Motor vehicle exhaust contains five of the components of smog: carbon monoxide, particulate matter, lead, nitrogen oxides, and volatile organic compounds.
Particulate matter (PM) is made up of very tiny solid or liquid particles that are small enough to remain suspended in the air. Scientists separate the particles into two categories, depending on their size. Coarse particles, referred to as PM10, are under 10 micrometres in size. A micrometre is 1 millionth of a metre. Coarse particles are 1/8th the size of a human hair. The fine particles, which are less than 2.5 micrometres in size, are in the category referred to as PM2.5. These particles are smaller than a single particle of flour.
Image 21. The relative size of beach sand, a grain of flour, and a fine particle less than 2.5 microns.
Particulate matter includes dust, dirt, soot, smoke and tiny particles of chemical pollutants. The major sources of particulate pollution are factories, power plants, trash incinerators, motor vehicles, construction activity, fires and natural dust blown around by the wind. The amount of particulate matter in the air can be worse in winter because we burn wood and other fuel to heat our houses, releasing tiny particles of pollutants. In big cities, where there are lots of cars, particulate matter can be worse than in rural areas where there are fewer cars. The amount of particulate matter can also be greater in places where there are lots of factories and industries that release pollutants into the air.
Activity: Particulate matter in the air can be collected. Have your students cover the outside of a small jar, or a small square of plastic, with petroleum jelly and place it outside. Leave it for 24 hours and then observe the dirt particles that were collected. It may be helpful to place a piece of white paper behind and/or use a magnifying glass. Several of these set-ups can be placed in different areas around the school or at home to see which area will collect the most particles.
Fast Fact: 20 percent of homes in Canada use wood as a secondary heating source. That number is higher in Atlantic Canada.
Ozone is the same gas, whether it is high up in the atmosphere or near the ground. In the stratosphere, ozone forms a protective barrier for harmful radiation from the sun (Refer to pages 12 and 44 in the Sky Watchers: Guide to Weather for more information). Near the ground, ozone is considered a pollutant and can be harmful to people, animals, plants and other materials.
Image 21. Oxygen, O2 is two oxygen atoms bonded together. The formula for ozone is 03, which is three oxygen atoms.
Unlike particulate matter, ozone is generally a colourless gas and cannot be seen in the air. However, at very high concentrations, ozone can have a bluish tinge. Ground-level ozone is referred to as a secondary pollutant. This means it is formed from other pollutants already present in the air. The other pollutants, mainly nitrogen oxides (NOx) and volatile organic compounds (VOCs), react with oxygen and energy from the sun to produce ground-level ozone. Because sunlight is required to form ozone, the concentrations in the air are normally higher in the summer, when temperatures are warmer and the sun's rays are stronger.
Tips: To help your students better understand the role of the sun in forming ozone, you may want to use a comparison with making Rice Krispie squares. Without heat to melt the marshmallows, you have no squares. The other pollutants will not form ozone without the energy from the sun to start the reaction.
You may want to revisit Activity 1 in the Sky Watchers: Guide to Weather about the sun's rays relative to the earth's rotation to illustrate the difference in the strength of the sun during different seasons.
The pollutants that are "cooked" to make ozone are formed by both man-made and natural sources. Nitrogen oxides are produced whenever natural gas, gasoline, diesel fuel, kerosene and oil are combusted; the sources include cars, trucks, power plants and factories. They are also released into the air by nature during forest fires and by volcanoes. VOCs are produced whenever the fuels above evaporate into the air. VOCs are also released directly to the atmosphere by trees.
Activity: To demonstrate the pollution from burning, light a candle and pass the bottom of a white glass plate through the flame. There should be a dark mark on the bottom of the plate where the flame touched. This is the pollution released from the burning of the wax.
To monitor the ground-level ozone concentrations in your area, try Activity 2
Image 22. Smog Trapped in Fraser Valley: Classical smog behaviour in the Fraser Valley.
Local weather conditions play a major role in the movement of air pollution. The severity of air pollution can be increased when local wind conditions and/or the unique topography of a region cause the pollutants to become trapped in a layer of relatively still air. Ground-level ozone is usually formed when there is a slow-moving high pressure system influencing the area providing stronger
sunlight and warmer temperatures. Typically, the warmer air will rise and the pollution will be dispersed by the wind. However, pollution can be trapped near the ground when a temperature inversion occurs. What is a temperature inversion? Well, normally the temperature decreases in the troposphere with height. A temperature inversion will form when the temperature increases with height resulting in a stable layer of air. This stable layer acts as a "lid" on the lower atmosphere, resulting in an environment more susceptible to higher pollution concentrations. When this occurs, the winds are light, and the pollution becomes trapped. In southern British Columbia, the delicate interaction between the local topography and the Pacific Ocean is especially important. These features, coupled with a strong temperature inversion, frequently result in atmospheric conditions favorable for elevated ground-level ozone episodes. For example, several cities, including the greater Vancouver region, lie within the Fraser Valley where the mountain walls trap the air. These unique geographical features, along with sea-to-shore breezes off the Strait of Georgia, promote the formation of a temperature inversion. As a result, air-flow patterns become restricted and help to contribute to the area's ozone problem. The air is often polluted by automobile exhaust and other sources and is trapped close to the ground where we breathe it in.
In Chapter 2 of the Sky Watchers Guide to Weather, you learned about the global wind patterns that travel around the earth. Pollution may be carried around the earth by these winds. The pollution that is generated in one place is transported by the wind and can affect people in other areas. Ground-level ozone and other pollutants can travel long distances, from hundreds to a few thousand kilometres in a single day. During this travel, pollutants can be deposited on the ground or on buildings, and undergo chemical changes. These chemical changes can result in an entirely different pollutant being formed. Volatile organic compounds and nitrogen oxides, for instance, may react with oxygen and energy from the sun to form ground-level ozone that will ultimately affect another area. There is always someone downstream of where pollution is released.
Have your students try Activity 3, The Clean Air Game, in the Activities section. It will help them to remember the concepts and vocabulary covered so far.
Our lungs inhale all the things in the air around us, including particulate matter and ground-level ozone. Elderly people and those with heart or lung disease - such as asthma, emphysema and chronic bronchitis - are particularly sensitive to air pollutants. When pollution levels are high, sensitive people may experience symptoms after only one or two hours outdoors. Children and active adults are also at a greater risk because they typically spend more time outside and engage in physical activities that increase their heart rate. Also, children tend to be more sensitive than adults because they require more air and thus breathe faster than adults - twice as much air per pound of body weight compared to adults (Journal of Environmental Health Perspectives).
Principal Ozone Problem Areas in Canada
Fast Fact: According to the Canadian Lung Association, one in five Canadians now has some form of respiratory problem and 5 to 10 percent of Canadian children have childhood asthma.
Exposure to ozone can irritate the nose and throat and cause chest tightness, coughing and wheezing. Increases in ozone levels in Canada have been linked to increased mortality, emergency hospital visits and admissions for respiratory problems. In sensitive people, the stress of ozone exposure can be particularly damaging. There is also evidence that ozone heightens the sensitivity of asthmatics to allergens. Other studies on animals have indicated that ozone exposure decreases the lungs' ability to ward off disease. The effects also include decreased lung capacity, which can impair performance in athletes.
Students can simulate the experience of those with asthma and other respiratory problems with Activity 4 in the Activities section.
Many of the adverse health effects resulting from exposure to particulate matter are similar to those for ozone, and are specific to the cardio-respiratory (heart-lung) system. When we inhale particulate matter, the particles can penetrate deep into the lungs. The smaller the particle, the deeper into the lungs it can penetrate. Recent studies have identified strong links between high levels of airborne particles and increased hospital admissions for heart and respiratory problems, as well as higher death rates from these ailments.
Fast Fact: According to a report commissioned by the Ontario Medial Association (OMA), air pollution costs Ontario citizens more than $1 billion a year in hospital admissions, emergency room visits and absenteeism. Approximately 1900 premature deaths occur per year in Ontario as a result of air pollution.
Plants also require air to grow. Ozone interferes with the ability of plants to produce and store food. That means that growth and reproduction are threatened along with weakening the overall health of the plant so they may be more susceptible to disease and pests. Some estimate that the provinces of British Columbia and Ontario each lose millions of dollars per year because of lower crop productivity due to high levels of ground-level ozone. Ozone damage can be seen on the foliage of some potato varieties in Atlantic Canada. Beans, tomatoes, potatoes, soya beans and wheat are all crops which are sensitive to ozone. Trees, which live longer than the plants above, are exposed to ozone year after year. If the effects of exposure add up over many years, which is believed to happen, entire forests can be affected. This means that other things, like the plants and animals that depend on the trees to provide shelter, are also affected by prolonged exposure to ground-level ozone.
Fast Fact: Rural pollution can be just as bad as urban pollution, depending on a combination of local weather conditions, topography, or the amount of pollution due to long-range transport.
Other materials you use in everyday life can be weakened by exposure to high levels of ozone. Rubber, textile dyes and fabrics, and certain types of paints and other coatings are either damaged or weakened by ozone exposure. Synthetic elastic materials can become brittle and crack, while the textiles and dyes fade faster than usual.
To demonstrate the effect of pollution on rubber, try Activity 5 in the Activities section.
As Sky Watchers, you have learned how Environment Canada meteorologists predict what the weather is going to be like where you live. You also know they predict how strong the UV radiation is going to be for the day. This is done so Canadians can be better prepared for any kind of weather, and can wear sunscreen and protective clothing to prevent sunburns. Environment Canada and your provincial, regional and local governments are also concerned about the air you breathe and the quality of that air. They want people to be able to make informed decisions and plan their activities around the quality of the air. In some cities, like Vancouver and Montreal, the local municipal governments are responsible for issuing the smog information for the local area. Just like you wouldn't plan to have a picnic in the rain, or fly a kite in the middle of a thunder and lightning storm, it is better to avoid strenuous outdoor activities when pollution levels are high. Generally, the highest levels of ozone are in the mid-to-late afternoon. If you want to have a game of soccer, where you will be running around a lot and breathing in a lot more air, depending on the specific conditions for the day, you should try and play in the morning, when the air quality is generally better. The forecast tells you when the air quality will be good or bad, so you can plan your outdoor activities around it.
Tips: For more information on Air Quality Forecasts and Services in your area, login to our website at Air Quality Health Index and select your region from the map.
Federal, provincial, regional and local governments are working together to keep Canadians informed about the level of air pollution in their communities, and to educate them about how to reduce smog and limit their exposure. Listen for the following:
To reduce your exposure to smog, listen for Smog Advisories and other air quality information. Avoid vigorous outdoor exercise when levels of ground-level ozone and airborne particles are high. People with heart and lung disease, especially asthma, should stay indoors if possible.
The categories for the smog forecasts range from good to very poor. In Atlantic Canada and the greater Vancouver area for instance, the categories are good, fair, poor and very poor. In Ontario, the lower categories are further divided into very good, good and moderate. When the forecast is fair, health officials recommend that people who are sensitive to pollution should try to restrict their activity and stay indoors.
Fast Fact: Saint John, NB was the first city in Canada to have a daily smog forecast. The forecast has been operating since 1997.
Most smog forecast programs operate between May and October. The concentrations of ground-level ozone are usually higher during this period due to warmer weather conditions. The number of times each summer that the higher levels are reached depends on where you live, weather conditions and can vary from year to year. If the summer is cool and wet, there will be fewer days with high smog levels. On the other hand, a hot and dry summer can result in additional days with high concentrations.
Try combining the weather forecasts your class can attempt in Chapter 5 of the Sky Watchers: Guide to Weather with a smog forecast. Activity 6 in the Activities section lists some helpful questions, and answers, along with an answer chart.
The Smog Advisory Program, developed in 1993 by Environment Canada, alerts citizens when ground-level ozone concentrations (smog) are expected to exceed the national standard. Smog Advisories are similar to weather warnings, in that they are only issued when conditions are expected to meet specific criteria. In Atlantic Canada, Health Advisories are also issued along with Smog Advisories, recommending that people with sensitivities to pollution consult their physicians. The key difference between Smog Forecasts and Smog Advisories is that the latter are only issued when smog levels threaten to become detrimental to the health of the general population. This occurs when levels are expected to reach the poor category.
It is important for the future of our planet, and the health of all living things, that we do what we can to reduce air pollution. Some simple solutions are using a fan instead of air conditioning whenever possible and not letting your car idle unnecessarily. However, by attempting to find alternatives, such as using public transportation or car-pooling, we can lessen our impact on the environment. In the future, it may be that we will be able to utilize other methods to provide us with energy. Solar energy and wind energy are both in use at present and may become more widely used as the technology improves. On the following page, there are some simple tips that you can copy to send home with the students. Encourage them to talk to their parents about trying to work for cleaner air.
Tips: Ask your students to think about all the things they do in a day that contribute to smog formation. Encourage them to keep track of environmentally-friendly choices so they can see the difference they are making.
Activity: Ask your students about what can be done to improve the impact we are having on the environment. Have them do research on alternative energy sources such as solar and wind energy.
Tips for Reducing Air Pollution
Many of the choices that we make every day have a direct impact on the amount of pollution that goes into our air from the way we get to work and school in the morning to the way we heat and cool our homes. Since burning fuel is an important part of smog formation, reducing energy use and making wise decisions about the products we use are important steps toward cleaner air. Learn as much as possible about alternative energy sources, and talk about your concerns about smog with other people-including your parents. The following are some simple tips to pass along.
Tight is right. Save fuel by upgrading and maintaining your home heating system, insulation and windows.
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