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Chapter 1

Overview

Air pollution is a problem and concern for many people who live in Ontario. Average air pollution levels in Ontario during the past 30 years have improved, but smog remains a concern especially in southern Ontario. Air pollution comes from many different sources including stationary sources such as factories, power plants and smelters; smaller area sources such as dry cleaners and degreasing operations; mobile sources such as cars, buses, trucks, planes and trains; and finally, natural sources such as forest fires, windblown dust and biogenic emissions from trees.

Many pollutants, including those that form smog (ozone and fine particles), remain in the atmosphere for long periods of time. These air pollutants can be generated both locally and regionally, and carried hundreds of kilometres by winds from province to province, state to state and country to country, affecting areas far removed from the source of the pollution.

This report tracks two kinds of air pollution trends: air concentrations based on actual measurements of pollutants in the ambient outdoor air, and air emissions based on best available estimates of the total mass of pollutants released into the air each year as provided by source engineers.

The Ontario Ministry of the Environment collects air quality data at 80 continuous monitoring sites across the province. These data are surrogates to determine the state of air quality in Ontario and help develop abatement programs to reduce the burden of air pollutants, address key air issues and assess the efficacy of policy and programs. Ambient air monitoring in Ontario provides information of the actual concentrations of selected pollutants in communities across Ontario. Table 1.1 shows the relationship between the monitored air pollutants and the current air issues.

For the past 30 years, the Ministry of the Environment has been monitoring air quality across Ontario and using this information to:

• inform the public about outdoor ambient air quality;
• provide smog alerts for public health protection;
• assess Ontario's air quality and evaluate trends;
• identify areas where criteria are exceeded and identify the origins of pollutants;
• provide the basis for air policy/program development;
• provide quantitative measurements to enable abatement of specific sources;
• determine the significance of pollutants from US sources and their effects on Ontario;
• provide air quality researchers with data linking environmental and human health effects to air quality.

This report, the 30^th in a series, summarizes the state of ambient air quality in Ontario during 2000. It covers the measured levels of the six traditional contaminants consisting of ozone (O₃), particulate matter (PM₁₀/PM _2.5), sulphur dioxide (SO₂), nitrogen dioxide (NO₂), carbon monoxide (CO) and total reduced sulphur (TRS) compounds. For the first time, the ministry's annual report contains data on ambient mercury (Hg) levels. The report also summarizes the results from the Air Quality Index (AQI) and Smog Alert programs for 2000. In addition, results for a selected number of VOCs are summarized and a perspective on the state of air quality in the Great Lakes Basin area is also presented.

The main focus of the 2000 publication is to report in a timely manner on the state of Ontario's ambient air quality. The data for the source monitoring sites, as in the past will be presented in a separate appendix document, along with the ambient data. Ontario continues to benefit from one of the most comprehensive air monitoring systems in North America. The network is designed to measure air quality at 80 continuous monitoring sites across the province and undergoes ongoing maintenance to ensure a high standard of quality control. With this data we can make informed decisions about what needs to be done to protect and improve our air quality.

Trends in Air Quality and Emissions

Each year the ministry gathers and analyzes air concentration data from ambient monitoring sites across Ontario. During the past 30 years, significant reductions have been achieved in ambient provincial pollution levels.

Ministry programs and policies have led the way to these significant reductions. One of the best examples is the 30-year sulphur dioxide trend (Figure 1.1). Sulphur dioxide is emitted primarily by burning fossil fuels containing sulphur, smelting operations, and in the pulp and paper processes in Ontario.

Figure 1.1: Trend of Sulphur Dioxide Concentrations (1971 – 2000)

Note: Annual composite mean based on 11 sites operated over 30 years.

Ontario Regulations 346 and 350, control orders on major smelting operations and the Countdown Acid Rain program have helped reduce SO₂emissions in the province by 82 per cent since 1971. A similar decrease in ambient SO₂ concentrations (83 per cent) has been recorded over the same 30-year period.

Other examples of air quality improvement: CO levels decreased 81 per cent during the past 30 years; NO₂ levels decreased 23 per cent and oxides of nitrogen (NO_X) 49 per cent over the past 26 years (Figure 1.2). These reductions occurred during significant population and economic growth in Ontario. Since 1971, the provincial population increased 53 per cent and vehicle kilometres travelled were up 87 per cent. Gross domestic product has increased 70 per cent since 1981 (Figure 1.3).

Figure 1.2: Change in Air Pollutant Concentrations (1971 – 2000)

Note: NO_x and NO₂ data from 15 sites beginning in 1975. CO data from 9 sites.

Figure 1.3: Ontario's Population, Vehicle-Kilometres Travelled and Gross Domestic Product (1971 – 2000)

Note: VkmT – vehicle kilometres travelled.

GDP – gross domestic product (1981 – 2000).

Source: Population and GDP – Statistics Canada; VkmT – Environment Canada.

Ground-level ozone and fine particles however, remain a concern in Ontario, especially in the Windsor-to-Ottawa corridor. Ozone and fine particles continue to exceed their respective ambient air quality criteria (AAQC) at the majority of monitoring locations in southern Ontario. The trend of the ozone seasonal means (summer and winter) for 1980 to 2000 is shown in Figure 1.4. It shows that there has been an increasing trend in the composite seasonal ozone means during the 21-year period. Similar findings of an increasing trend for ozone have been noted elsewhere in North America.

Figure 1.4: Trend of Seasonal Ozone Means at Sites Across Ontario (1980 – 2000)

Note: Data from 18 ozone sites; summer (May to Sept.); winter (Dec. to Feb.).

Occurrences of ozone exceeding the criterion, and/or the number of such occurrences covering wide areas, tend to vary substantially from year to year because of the weather. The year 2000 is a good example of how weather can affect air quality and, in particular, ozone levels. In 2000, the second lowest total of ozone exceeedances was recorded since 1980. This is mostly attributed to the 2000 smog season (May to September) being characterized as cooler and wetter than normal.

Significant amounts of ozone and its precursors are carried into Ontario from the United States. During hot summer days it is estimated that more than half of the province's ozone can be attributed to transboundary pollution. Figure 1.5 shows the prevailing winds during days of widespread elevated ozone levels in Ontario.

Figure 1.5: Transboundary Air Flow into Ontario

Throughout the 1990s and more recently from 1996 to 2000, the ministry increased monitoring for inhalable particles due to growing health concerns, and its association with transboundary pollution. Figure 1.6 shows the growth of Ontario's ambient PM program from 1991 to 2000. Results are discussed in Chapter 3.

Figure 1.6: Expansion of Ontario's Ambient PM Monitoring Program (1991 – 2000)

Note: Metals in PM₁₀ and sulphate in PM₁₀ are available from 24- Hour PM₁₀ Samples.

TEOM -Tapered Element Oscillating Microbalance.