Environmental Indicators
1 Air Quality

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Regulations designed to improve air quality trends target six main pollutants: sulphur dioxide (SO2), nitrogen dioxide (NO2), ground level ozone (O3), carbon monoxide (CO), total suspended particulates (TSPs), and lead (Pb).1 The primary synthetic sources of these pollutants are automobiles and industrial activity such as mining, smelting, production of fossil fuels, pulp and paper and chemicals, and manufacturing. These pollutants are also created by natural sources.

To measure air quality, two types of data are used: ambient concentrations and emissions estimates. Ambient concentrations are the actual amount of a pollutant in the air. They are usually reported in parts per million (ppm), parts per billion (ppb), or micrograms per cubic metre (mg/m3). In Canada, the National Air Pollution Surveillance (NAPS) network traces common air contaminants with 461 monitoring instruments located in 198 cities and towns across the country (Shelton 1999).2 This program commenced in January 1970 with only 43 monitoring instruments in 14 urban centres (Furmanczyk 1987: 2).

Emissions estimates are calculations of the amounts and types of pollutants emitted by various sources over a given period. These calculations are based on many factors, including the level of industrial activity, changes in technology, fuel-consumption rates, vehicle miles travelled, and other activities that cause air pollution. They do not include releases of the pollutants from natural sources. Although emission statistics provide some useful information regarding air-quality trends, they are less reliable indicators than ambient concentrations because they are estimates generated by models rather than actual measures. In addition, frequent revisions in the calculation methods used to estimate emissions make comparisons between years less meaningful than comparisons of annual ambient levels.

In this section, each pollutant is described and then compared to Canada's National Ambient Air Quality Objectives (NAAQOs) for the protection of human health and the environment. Canada has a three-tiered system of objectives that defines maximum desirable, acceptable, and tolerable levels of air pollution for periods of one year, 24 hours, 8 hours or one hour, depending on the pollutant.3 According to Environment Canada:

the maximum desirable level defines the long-term goal for air quality and provides a basis for an anti-degradation policy in unpolluted areas of the country. The maximum acceptable level is intended to provide adequate protection against adverse effects on humans, animals, vegetation, soil, water, materials, and visibility. The maximum tolerable level is determined by time-based concentrations of air contaminants. When air pollutants reach this level of concentration appropriate action is required without delay to protect the health of the general population. (Environment Canada 1999b)

Table 1.1 lists Canada's NAAQOs alongside the guidelines of the World Health Organization (WHO). The table also includes a description of the effects on human health and the environment the correspond to each category. When the strictest standard (desirable) is met, there are no effects on human health and the environment.

Sources: Canada guidelines: Environment Canada 1999b; WHO guidelines: USEPA 1995c: 7-4;
Environment Canada 1991c.

For each pollutant discussed in the section, we provide a graph showing the average of the stations' annual means. The strictest annual health standard is included so the reader can see instantly whether there are any health concerns associated with that level of pollution. To provide a better illustration of the number of stations meeting the annual standards of Canada's NAAQOs, the tenth, fiftieth, and ninetieth percentiles (the box around each point) of stations meeting the standards are included. The top of the box illustrates the ninetieth percentile for the calculation. This indicates that 90 percent of the stations have an annual mean equivalent to, or below, this level. Similarly, the line in the middle represents the fiftieth percentile and the line at the bottom of the box represents the tenth percentile. They illustrate the levels for which 50 percent and 10 percent of the stations have an annual mean equivalent or below. It is important to note that the number of stations monitoring each pollutant has changed over the years.

The percentage of stations with readings above the NAAQOs short-term standards is also examined (see tables 1.2-1.6). This is calculated by dividing the number of stations with at least one reading above the NAAQOs by the total number of stations. In reading this data, it is important to note that one reading above the standard may not be critical, considering that some stations have several thousand readings in a year. Also a single day's exceedence can be influenced by meteorological factors such as temperature, sunlight, air pressure, humidity, wind, rain, and so on. Despite these limitations, the data provides a good complement to the annual data, illustrating changes in the number of stations meeting short-term concentration objectives.

Sulphur dioxide

Sulphur dioxide (SO2) is a colourless gas that, in sufficient concentrations, has a pungent odour. There is concern about levels of SO2 since it is a precursor to acid rain. Acid rain in sufficient concentrations can cause the acidification of lakes and streams, accelerate the corrosion of buildings and monuments, and impair visibility. As a result, in 1985 Manitoba, Ontario, Quebec, New Brunswick, Nova Scotia, Prince Edward Island, and Newfoundland created the Canadian Acid Rain Control Program, agreeing to cut total annual SO2 emissions to 2.3 million tones by 1994 (Statistics Canada 1998: 44). They surpassed this target by 1993. In 1991, Canada signed the Canada/United States Air Quality Agreement for the reduction of SO2 and NOx emissions. Canada's obligations under this agreement include the establishment of a permanent national limit on SO2 of 3.2 million tonnes by the year 2000 (USEPA 1995d: ES-1). Canada has met this objective since 1992.

Although acid rain remains a topical concern, there is a debate among scientists whether acid rain does indeed damage forests and crops as well as endanger wildlife and human health. After ten years of study, the United States National Acid Precipitation Assessment Program (NAPAP) concluded that acid rain has had little or no effect on wildlife, forests, crops, or human health (Bast, Hill, and Rue 1994: 74-81). In fact, it cites cases in which acid rain has had a positive effect on soil and lakes as it can enhance vital nutrients and reduce pH levels where alkalinity is a problem. There is also uncertainty about the natural acidic levels for different lakes. A chemist named Edward Krug argues that some lakes are becoming more acidic because of less human influence. Whereas slash-and-burn timbering practices in the early 1900s resulted in uncontrolled erosion and, consequently, in large deposits of alkaline topsoil in nearby lakes, more sustainable forestry practices have reduced erosion and have allowed the lakes to return to their natural acidic levels (Easterbrook 1995: 169).

Some Canadian scientists, however, estimate that even with full implementation of the Canada/United States Air Quality Agreement, close to 800,000 km2 in south-eastern Canada will receive levels of acid rain that could have a negative effect on the environment. They have estimated that a further 75-percent emission reduction in parts of eastern Canada and the United States is necessary to protect sensitive ecosystems in the area (Statistics Canada 1998: 45).

Trends for sulphur dioxide

Figure 1.1 shows that the ambient level (the average of the monitoring stations' annual means) for SO2 decreased by 60.6 percent in Canada between 1974 and 1997. Since 1990, over 90 percent of the individual stations have reported annual means meeting Canada's strictest annual health standard. Figure 1.2 shows the downward trend in annual mean concentrations of SO2 for three cities across Canada.

Figure 1.1 Ambient Levels of Sulphur Dioxide (ppb)

Source: data provided by Shelton 1999; calculations by authors.

Figure 1.2 Ambient Levels of Sulphur Dioxide in Montreal, Hamilton and Vancouver

Source: OECD 1999: 55. (This figure includes the three cities for which data are available from the OECD.)
Note that this figure shows annual mean concentrations presented as values relative to the base-year 1988. The1988 base-year levels are 14.0 mg/m3 for Montreal, 25 mg/m3 for Hamilton, and 16 mg/m3 for Vancouver./p>

During the period from 1977 to 1997, there were also significant reductions in the number of stations with readings exceeding the 1-hour and 24-hour objectives (table 1.2). In 1997, only 20.7 percent of stations failed to meet 1-hour desirable objectives, compared to 42.2 percent in 1977. Similarly, in 1977, 10.3 percent of stations had readings exceeding the 1-hour acceptable level, down from 19.3 percent in 1977.4 In 1997, 17.2 percent of stations had readings exceeding the 24-hour desirable level and 3.4 percent of stations exceeded the 24-hour acceptable level. No stations have exceeded the 24-hour tolerable level in the past decade.

Emissions of sulphur dioxide (SO2) in Canada fell 59.7 percent between 1970 and 1997 (figure 1.3). The increased use of control devices by industry has contributed to the decline in emissions. Improvements in the processes used, smelter closures, acid-plant adoption, the use of low-sulphur coal, the adoption of coal blending and washing procedures, and the conversion to cleaner fuels (e.g., natural gas and light oil) have also contributed to the decline (USEPA 1996a: 29). Emissions by industrial sources decreased by 37.6 percent between 1980 and 1995. The greatest decline, however, was in combustion and incineration sources where emissions decreased 59.1 percent and 58.4 percent, respectively, over the same period. Figure 1.4 illustrates the sources of SOx for 1995. The main contributor to SOx emissions is industrial sources, particularly, the non-ferrous mining and smelting industry.

Source: data provided by Shelton 1999; calculations by authors.

Figure 1.3 Sulphur Dioxide (SO2) Emission Estimates

Source: OECD 1999.

Figure 1.4 Sulphur Oxide (SOx) Emissions by Source, 1995

Source: Environment Canada 1998a; note that data does not include natural sources.

Nitrogen dioxide

Nitrogen dioxide (NO2) is a highly reactive gas that is readily formed through the combination of nitric oxide (NO) with oxygen. This reaction is typically a natural process, occurring through lightning, volcanic activity, bacterial action in soil, and forest fires. Most of the nitrogen oxide compounds needed for this reaction however, originate from human activities. Nitrogen oxides (NOx) are the sum total of NO, NO2, and other oxides of nitrogen. The combustion of fossil fuels by automobiles, power plants, industry, and household activities all contribute to their concentrations in the environment.

Levels of NOx in the environment are of concern since they combine with volatile organic compounds (VOCs) in the presence of sunlight to form ground-level ozone. This process contributes to the formation of urban smog. Nitrogen oxides also play a major role in atmospheric photochemical reactions that contribute to acid rain. Although the ambient levels of all nitrogen oxides are a concern, environmental agencies generally track NO2 since NO is so readily converted to NO2 in the environment. NO2 is also the easiest to detect because of its presence in higher concentrations.

Trends for nitrogen dioxide

From 1974 to 1997, the Canadian annual mean decreased 21.6 percent, from 21.3 to 16.7 ppb. Figure 1.5 illustrates that throughout this period the composite annual mean has remained below the strictest health standard (the "desirable" level). Figure 1.5 also illustrates that 90 percent of the stations have, throughout this period, been below the maximum acceptable level and, since 1990, have been below the desirable level. All stations have met the desirable level since 1992, with the exception of one exceedence in 1996. Cities across Canada have shown a marked decline since the earliest available data in 1986 (see figure 1.6).

Figure 1.5 Ambient Levels of Nitrogen Dioxide (ppb)

Source: data provided by Shelton 1999; calculations by authors.

Figure 1.6 Ambient Levels of Nitrogen Dioxide (ppb) in Montreal, Hamilton, Ottawa, and Vancouver

Source: OECD 1999: 58. (This figure includes the four cities for which data are available from the OECD.)
Note that 1988 base-year levels are 48.0 mg/m3 for Montreal, 46 mg/m3 for Hamilton,
45 mg/m3 for Ottawa, and 51 mg/m3 for Vancouver.

Trends in short-term concentrations similarly illustrate improvements in the concentration of nitrogen dioxide (table 1.3). In 1977, 13.6 percent of monitoring stations reported readings that exceeded the 1-hour maximum acceptable level standard, and 15.9 percent had readings exceeding the 24-hour maximum acceptable level. By 1997, all readings at all stations met both the 1-hour and 24-hour maximum acceptable levels.

Source: data provided by Shelton 1999; calculations by authors.

Emissions data for NOx show a trend opposite to that of ambient levels. Canadian emissions increased 51.3 percent from 1970 to 1996 (figure 1.7). This increase in the emissions of NOx is puzzling in light of the reduction in ambient NO2. In considering this discrepancy, it is important to recall that emissions data are estimates and ambient data are more reliable as they are actual measurements from the air.

Figure 1.7 Nitrogen Oxide Emission Estimates

Source: OECD 1999

Figure 1.8 illustrates the breakdown of sources of NOx emissions for 1995. Transportation accounts for over one-half of the total level of emissions.

Figure 1.8 Nitrogen Oxide Emissions by Source, 1995

Source: Environment Canada 1998a; note that data does not include natural sources.

Ground-level ozone

Ground-level ozone (O3) is a colourless and highly irritating gas. It is formed just above the earth's surface through the reaction of NOx and volatile organic compounds (VOCs). Since this chemical reaction is facilitated by the presence of heat and sunlight, ozone is typically more of a concern during the summer months.

Since ozone is the main contributor to urban smog, regulators target emissions of VOCs to combat the problem. VOCs are a subgroup of hydrocarbons (HCs); they enter the atmosphere through evaporation of automotive fuel (from the fuel tanks of automobiles), paints, coatings, solvents, and consumer products, such as lighter fluid and perfume. VOCs also occur naturally as a result of photosynthesis.

Increasing levels of ozone have led regulators to develop more stringent standards. In 1998, 12 Canadian Ministers of the Environment endorsed the Canada-Wide Agreement on Environmental Harmonization. This agreement included a commitment to develop Canada-wide standards for both ground-level ozone and particulate matter. These new standards were accepted in November, 1999 for endorsement in May, 2000. Much of the concern about ozone levels stems from the Canadian study of NOx and VOC (Environment Canada 1997a) that states that the current 1-hour maximum acceptable level for ozone does not fully protect human health. It also reports that there is "no discernible human health threshold for ground-level ozone," meaning that any improvement in ambient ozone levels is expected to have public health benefits (Environment Canada 1997a: 3).

Trends for ground-level ozone

The level of ambient ozone increased from 14.7 ppb to 21.7 ppb (47.6 percent) between 1974 and 1997 (figure 1.9). During this period the Canadian mean (the average of the annual means measured at all stations) has consistently been above the maximum acceptable level. One can also see from figure 1.9 that less than 50 percent of individual stations across the country have reported annual means below the maximum acceptable level.

Figure 1.9 Ambient Levels of Ground Level Ozone (ppb)

Source: data provided by Shelton 1999; calculations by authors.

Data on the percentage of stations with readings exceeding short-term concentration objectives also suggests that ozone is increasingly becoming a concern (table 1.4). Although the number of stations reporting readings above 1-hour maximum acceptable and tolerable levels has decreased, the number of stations reporting readings above the 1-hour desirable level has increased. In 1977, 95 percent of stations reported readings above the desirable level. This percentage increased to 97.9 percent in 1997.5 For 22 stations, more than 5 percent of their total readings are above the desirable level.6

Source: data provided by Shelton 1999; calculations by authors.

VOC emissions, which contribute to the formation of ground-level ozone, increased 27.1 percent between 1980 and 1997. However, as illustrated in figure 1.10, emissions have remained relatively constant since 1985. This trend illustrates that ambient ozone levels do not directly or predictably reflect VOC emissions. Yet, it is interesting to examine the source of VOC emissions since it provides a guideline for targeting ozone levels. Figure 1.11 demonstrates that the main sources of VOCs are industry and open sources. In particular, the oil and gas industry accounts for 19.3 percent of emissions and forest fires contribute 25.2 percent.

Figure 1.10 Volatile Organic Compounds Emissions Estimates

Source: OECD 1999

Figure 1.11 Volatile Organic Compound Emissions by Source, 1995

Source: Environment Canada 1998a; note that data does not include natural sources.

Carbon monoxide

When fuel and other substances containing carbon burn without sufficient oxygen, carbon monoxide (CO), a colourless, odourless gas is produced. Trace amounts of CO occur naturally in the atmosphere but most emissions come from automobiles. Levels of CO are of particular concern to monitoring organizations because of their effect upon human health: CO reduces the capacity of red blood cells to carry oxygen to body tissues. Since CO poisoning occurs as a result of short-term exposure, health guidelines do not include annual recommendations for ambient CO levels. However, 8-hour and 1-hour guidelines are available.

Trends for carbon monoxide

Annual ambient levels of CO have improved significantly in Canada over the past two decades. Between 1974 and 1997, levels declined from 2.3 to 0.6 ppm, a 73.9 percent reduction. As illustrated in figure 1.12, this decline can be seen in all stations. In 1974, the highest annual mean measured at an individual station was 5.1 ppm whereas in 1997 it was 1.3 ppm. Ninety percent of stations have reported annual means below 1.1 ppm since 1991.

Figure 1.12 Ambient Levels of Carbon Monoxide (ppm)

Source: data provided by Shelton 1999; calculations by authors.

Table 1.5 displays the percentage of stations with readings exceeding NAAQOs levels. Whereas, in 1977 68.8 percent of stations had readings above the 1-hour desirable level, in 1997 the percentage of stations with exceedences fell to only 4.3 percent.7 The number of stations with readings exceeding the 8-hour desirable level declined from 85.4 percent to 17.4 percent. All stations have kept readings below 1-hour and 8-hour maximum acceptable levels since 1992.

Source: data provided by Shelton 1999; calculations by authors.

Carbon monoxide emissions declined 12.4 percent between 1970 and 1997 (figure 1.13). These reductions can partially be attributed to cleaner automobiles and more fuel-efficient industrial processes. To meet strict motor-vehicle regulations adopted in the early 1970s, exhaust-gas recycling systems (EGRS) were installed and some older vehicles were retired. This has led to vastly reduced emissions per vehicle. For example, North American cars built in 1993 emitted 90 percent less NOx, 97 percent less hydrocarbon, and 96 percent less CO than cars built two decades earlier (Bast, Hill, and Rue 1994: 111). There has also been an 87.5 percent reduction in CO emissions from incinerators between 1980 and 1995. Figure 1.14 illustrates the composition of CO emissions for 1995. The two main sources are transportation (39.2 percent) and open sources (mainly forest fires).

Figure 1.13 Carbon Monoxide Emission Estimates

Source: OECD 1999

Figure 1.14 Carbon Monoxide Emissions by Source, 1995

Source: Environment Canada 1998a; note that data does not include natural sources.

Total suspended particulates

Suspended particulates are small pieces of dust, soot, dirt, ash, smoke, liquid vapour, or other matter in the atmosphere. Sources may include forest fires and volcanic ash as well as emissions from power plants, motor vehicles, and waste incineration, and dust from mining.

Particulates are an irritant to lung tissue and may aggravate existing respiratory problems and cardiovascular diseases. Once lodged in the lungs, certain particulates may contribute to the development of lung cancer. The smallest particulates pose the greatest threat to human health because they are able to reach the tiniest passages of the lungs. Yet, Canada's National Ambient Air Quality Objectives (NAAQOs) focus only on total suspended particulates. In 1998, 12 Canadian Ministers of the Environment endorsed the Canada-Wide Agreement on Environmental Harmonization. This agreement included a commitment to develop Canada-wide standards for both particulate matter and ground-level ozone. These new standards were accepted in November, 1999 for endorsement in May, 2000.

Trends for total suspended particulates

Data from 1975 to 1997 show a 52.6 percent reduction in the ambient levels of total suspended particulates in Canada. Ninety percent of stations have reported annual means below the maximum acceptable level since 1983 (figure 1.15). Since 1990, 90 percent of stations have also met maximum desirable levels. Although the maximum station reading has decreased by 56.2 percent since 1974, some stations continue to report annual means above the maximum acceptable level.

Figure 1.15 Ambient Levels of Total Suspended Particulates (mg/m3)

Source: data provided by Shelton 1999; calculations by authors.

The number of stations with readings above the short-term concentration standards also has decreased over the past two decades (table 1.6). In 1977, 81.7 percent of stations had readings exceeding the 24-hour maximum acceptable level. This number decreased to 37.8 percent in 1997. Similarly, in 1977, almost ten percent of stations had readings above the tolerable level whereas only 2.7 percent did in 1997.8 Levels of total suspended particulates have been decreasing steadily in cities across Canada since 1986, the earliest year for which data are available (see figure 1.16).

Source: data provided by Shelton 1999; calculations by authors.

Figure 1.16 Ambient Levels of Total Suspended Particulates (mg/m3) in Montreal, Hamilton, and Vancouver

Source: OECD 1999: 61. (This figure includes the three cities for which data are available from the OECD.)
Note that 1988 base-year levels are 48.0 mg/m3 for Montreal, 81 mg/m3 for Hamilton, and 35 mg/m3 for Vancouver.

Despite decreases in ambient levels of total suspended particulates, emissions estimates have increased since 1985 (figure 1.17). However, 1996 levels are 9.0 percent lower than estimated 1980 levels. Figure 1.18 shows that most of the emissions of total suspended particulates are from transportation (59.8 percent of total suspended particulates originate from dust on roads).

Figure 1.17 Total Suspended Particulate Emission Estimates

Source: OECD 1999

Figure 1.18 Total Suspended Particulate Emissions by Source, 1995

Source: Environment Canada 1998a; note that data does not include natural sources.

Lead

Lead is a soft, dense, bluish-grey metal. Its high density, softness, low melting point, and resistance to corrosion make it of value in the production of piping, batteries, weights, gunshot, and crystal. Until recently, automobiles were the source of most lead emissions although small quantities of lead are naturally present in the environment. Lead is the most toxic of the main air pollutants. When it is ingested, it accumulates in the body's tissues. In high concentrations, it can cause damage to the nervous system and the brain, seizures, and behavioural disorders. In addition, recent evidence suggests that exposure to lead may be associated with hypertension and heart disease (USEPA 1995c: 2-6). Since lead is the most toxic of the main air pollutants, environmental and health guidelines for lead are stricter than those for other air pollutants. Canada is committed to reducing levels as low as technologically feasible, although no explicit objectives have been set. The maximum set by the World Health Organization (WHO) for the protection of human health is 1.0 mg/m3.

Trends for lead

The decline in ambient lead concentration is the greatest success story in the efforts to reduce air pollution. Ambient lead concentration fell 88.2 percent in Canada between 1974 and 1997 (figure 1.19). Although the Canadian average has been below the WHO's standard throughout this period, it was not until 1982 that all individual stations reported means below the health standard. By 1990, all stations had reduced their annual means to less than one-tenth of WHO's standard (0.1 mg/m3).

Figure 1.19 Ambient Levels of Lead (mg/m3)

Source: data provided by Shelton 1999; calculations by authors.

In Canada, emissions fell 73.9 percent from 1978 to 1995 and automobile emissions fell 87.8 percent from 1973 to 1988 (figure 1.20). Note the dramatic decrease in concentrations of lead between 1988 and 1990 in cities across Canada (see figure 1.21). Most of this reduction was due to the introduction of unleaded gasoline and the elimination of lead compounds in paints and coatings.

Figure 1.20 Lead Emission Estimates

Source: OECD 1999

Figure 1.21 Ambient Levels of Lead in Montreal, Hamilton, and Vancouver

Source: OECD 1999: 65. (This figure includes the three cities for which data are available from the OECD.)
Note that 1988 base-year levels are 0.07 mg/m3 for Montreal, 0.09 mg/m3 for Hamilton,
and 0.14 mg/m3 for Vancouver.

Air quality in selected cities

To assess overall air quality in urban areas, Environment Canada uses the Index of the Quality of Air (IQUA). This index converts individual pollutant concentrations to a scale ranging from 1 to 125. On this scale, 0 to 25 is "good," 25 to 50 is "fair," 50 to 100 is "poor," and 100 to 125 is "very poor." These intervals match the NAAQOs, with the desirable, acceptable and tolerable levels defining the limit of each section. The advantage of using the IQUA scale is that it converts all the air pollutant data to a common scale so that an average can be obtained. This average is a good measure of overall ambient air quality.

Table 1.7 shows the number of good, fair, and poor days in each major urban centre from 1990 to 1995. Data show that the number of poor days for half of the cities are low but variable: St John's, Halifax, Montreal, Quebec City, Ottawa, and Vancouver have consistently had less than ten poor days throughout the year. Regina and Winnipeg have reported fewer than 10 days of poor air quality since 1993. Some cities have even reported no poor quality days during this period. For example, Vancouver, Regina, and St John's did not have any poor air quality days in 1995.

Source: Statistics Canada 1998: 59-60.

Although the time period for this data is too short to determine trends, the variation among years is interesting to note. Over this period, there was little change in the number of poor days in most of the urban areas, although some cities have had decreases in the number of good days. Toronto reported 268 good days in 1992 but only 169 in 1995. Similarly, Hamilton had 236 good days in 1992 but only 184 in 1995. Most cities reported at least 200 good days in any year.

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