Location: Ministry Home > Air > Air Quality > Air Quality Report 2000

This is a HTML version of the original PDF document. The HTML version is being provided for reading purposes only and is not the official version of the document.

Chapter 5

Air Quality Index (AQI) and Smog Alert Program

Air Quality Indices (AQI)

The Ministry of the Environment operates an extensive network of air quality monitoring sites across the province. In 2000, thirty-four of these sites in 24 urban centres and six rural areas form the basis of the Air Quality Index (AQI) network. The Air Quality Office at the Environmental Monitoring and Reporting Branch continually obtains data for several criteria pollutants from the 34 sites. In 2000, for the first time since the inception of the AQI program in 1988, rural AQI values were reported during the smog season (May 1 - September 30).

The AQI network provides the public with real-time air quality information across the province. The AQI is based on pollutants that have adverse effects on human health and the environment. The pollutants are sulphur dioxide (SO₂), ozone (O₃), nitrogen dioxide (NO₂), total reduced sulphur (TRS) compounds, carbon monoxide (CO) and suspended particles (SP) measured as the coefficient of haze (COH). At the end of each hour, the concentration of each pollutant measured at a particular site is converted into a number that ranges from zero upwards using a common scale or index. The calculated number for each pollutant is called a sub-index.

At a given site the highest sub-index for any given hour becomes the AQI. The lower the index, the better the air quality. The index values, corresponding categories and potential health and environmental effects are shown in Table 5.1.

If the AQI value is below 32, the air quality is considered good. For AQI values in the 32-49 range (moderate category) there may be some adverse affects on very sensitive people. For index values in the 50-99 range (poor category) the air quality may have some short term adverse effects on the human or animal populations, or may cause significant damage to vegetation and property. With an AQI value of& 100 or more (very poor category) the air quality may cause adverse effects for a large proportion of those exposed.

Computed air quality indices and air quality forecasts are released to the public and news media at set intervals each day. The public can access the index values by calling the ministry's automatic telephone answering device (ATAD), English recording: 1-800-387-7768 or in Toronto 416-246-0411, and French recording: 1-800-221-8852. The AQI values can also be obtained from the ministry's Web site: www.airqualityontario.com.

Table 5.1: Air Quality Index Pollutants and Their Impact
Index	Category	Carbon Monoxide (CO)	Nitrogen Dioxide (NO 2)	Ozone (O3)	Sulphur Dioxide (SO2)	Suspended Particles (SP)	SO2 + SP As measured by the API)	Total Reduced Sulphur (TRS) Compounds
0-15	Very good	No known harmful effects	No known harmful effects	No known harmful effects	No known harmful effects	No known harmful effects	No known harmful effects	No known harmful effects
16-31	Good	No known harmful effects	Slight odour	No known harmful effects	Damages some vegetation in combination with ozone	No known harmful effects	No known harmful effects	Slight odour
32-49	Moderate	Blood chemistry changes , but no noticeable impairment	Odour	Respiratory irritation in sensitive people during vigorous exercise; people with heart/lung disorders at some risk; damages very sensitive plants	Damages some vegetation	Some decrease in visibility	Damages vegetation (i.e. tomatoes, white beans due to sulphur dioxide)	Odour
50-99	poor	Increased symptoms in smokers with heart disease	Air smells and looks brown. Some increase in bronchial reactivity in people with asthma	Sensitive people may experience irritation when breathing and possible lung damage when physically active; people with heart/lung disorders at greater risk; damages some plants	Odourous; increasing vegetation damage	Decreased visibility; soiling evident	Increased symptoms for people with chronic lung disease	Strong odour
100-over	verypoor	Increasing symptoms in non- smokers with heart diseases; blurred vision; some clumsiness	Increasing sensitivity for people with asthma and bronchitis	Serious respiratory effects, even during light physical activity; people with heart/lung disorders at high risk; more vegetation damage	Increasing sensitivity for people with asthma and bronchitis	Increasing sensitivity for people with asthma and bronchitis	Significant effects for people with asthma and bronchitis	Severe odour; some people may experience nausea and headaches

Air quality forecasts are provided daily based on meteorological conditions and short-term pollution levels in Ontario and bordering U.S. states. These forecasts are provided with the AQI report on the ATAD and can also be accessed via the ministry's Web site.

Summary AQI levels (2000)

Table 5.2 shows the number of hourly AQI values for the 34 monitoring locations, according to the descriptive category and the pollutant responsible for the AQI above 31. Air quality was most often in the "good to very good" categories at all AQI sites across the province. Based on the cumulative total number of monitoring hours (288,351) at the 34 sites, on average, good to very good air quality was reported 95.6 per cent of the time, moderate and poor air quality 4.2 percent and 0.2 percent of the time, respectively. Three sites, Ottawa, Cornwall and North Bay, did not record any hours of poor air quality. A total of 696 hours of poor air quality were recorded in 2000, based on data from the 34 sites. The six rural AQI sites were responsible for approximately 50 per cent of the poor air quality hours recorded. This means that the 28 urban sites reported only 350 hours of poor air quality.

Figure 5.1 shows composite pie diagrams of the percentages of very good, good, moderate and poor air quality recorded at sites across the province. The pie diagram on the left shows category percentages and that on the right breaks down the poor air quality slice into percentages of pollutants associated with the AQI above 49. Poor air quality at the majority of the AQI sites was due only to ozone. This pollutant accounted for approximately 97 per cent of the number of poor air quality hours recorded during 2000 at the AQI sites. TRS accounted for approximately 3 per cent of the poor AQI values and was recorded primarily at Windsor West.

The geographical distribution of the number of days of AQI greater than 49 is shown in Figure 5.2. The highest number of poor days was recorded at Long Point (20 days), a rural AQI site. For urban sites, the Windsor West site recorded 14 days. Ten of these days, however, were due to high levels of TRS and this reflects the influence of the nearby emission sources in Michigan. In contrast, the Windsor Downtown site recorded nine days all due to high levels of ozone.

Table 5.2: Air Quality Index Summary (2000)
Number of Hours in AQI Range								# of hours Pollutant Responsible for AQI > 31
		V-Good	Good	Mod.	Poor	V-Poor								# of days	# of days
Stn.ID	City/Town	0-15	16-31	32-49	50-99	100+	Valid hours	SP	O3	TRS	SO2	CO	NO2	1h >31	1h >49
12008	Windsor Downtown	5915	2473	374	22	0	8784	0	396	X	0	0	0	69	9
12016	Windsor West	5948	2353	442	39	0	8782	0	358	123	0	X	0	94	14
13021	Merlin	4459	3749	504	33	0	8745	X	537	X	X	X	X	84	9
14064	Sarnia	4226	4008	433	15	0	8682	0	444	4	0	0	0	80	7
15020	Grand Bend	2461	5404	813	76	0	8754	X	889	X	X	X	X	113	17
15025	London	5200	3079	295	20	0	8594	0	315	X	0	0	0	58	5
18007	Tiverton	1917	6176	574	36	0	8703	X	610	X	X	X	X	77	8
22071	Simcoe	3509	4261	795	79	0	8644	X	874	X	0	X	0	111	14
22901	Long Point	2974	4676	961	105	0	8716	X	1066	X	0	X	0	122	20
26060	Kitchener	4581	3785	393	25	0	8784	2	416	X	0	0	0	74	6
27067	Niagara Region	5662	2753	265	14	0	8694	0	279	X	0	0	0	55	3
28028	Guelph*	2218	1714	223	11	0	4166	X	234	X	X	X	X	42	4
29000	Hamilton Downtown	5778	2721	266	13	0	8778	8	252	19	0	0	0	58	5
29114	Hamilton Mountain	4958	3364	428	22	0	8772	0	449	1	0	X	0	79	5
29118	Hamilton West	6014	2555	206	8	0	8783	0	212	2	0	0	0	41	2
31103	Toronto Downtown	5701	2595	290	12	0	8598	X	302	X	0	0	0	56	4
33003	Toronto East	5651	2703	295	11	0	8660	X	306	X	X	X	0	58	3
34020	Toronto North	5238	3265	231	8	0	8742	X	239	X	X	X	0	50	2
35003	Toronto West	5569	2811	361	24	0	8765	X	385	X	0	0	0	71	4
44008	Burlington	4783	3526	452	14	0	8775	X	466	X	0	0	0	89	2
44015	Oakville	5035	3297	333	14	0	8679	22	325	0	0	0	0	74	5
45025	Oshawa	4939	3615	186	6	0	8746	X	192	X	X	X	0	45	2
46089	Brampton*	3272	1591	199	10	0	5072	X	209	X	0	0	0	38	3
46110	Mississauga	5186	3135	424	21	0	8766	17	427	X	1	0	0	88	4
48002	York Region	3236	5031	412	15	0	8694	X	427	X	X	X	0	75	3
49010	Haliburton	2874	5290	488	13	0	8665	X	501	X	X	X	0	74	4
51001	Ottawa	5495	3194	70	0	0	8759	0	70	X	0	0	0	20	0
52020	Kingston	5416	3066	204	8	0	8694	X	212	X	X	X	X	44	2
56051	Cornwall	4209	4351	176	0	0	8736	0	169	7	0	0	0	38	0
59006	Peterborough	3154	5054	454	17	0	8679	X	471	X	0	0	0	76	4
63200	Thunder Bay	4253	4444	83	1	0	8781	0	65	19	0	0	0	22	1
71068	Sault Ste.Marie	3925	4605	221	1	0	8752	10	208	4	0	X	0	46	1
75010	North Bay	4521	4001	101	0	0	8623	0	101	X	X	X	X	20	0
77203	Sudbury	3787	4781	213	3	0	8784	0	211	0	5	0	0	49	3
X - Pollutant not measured
* - Station started up in summer 2000

Figure 5.1: Air Quality Index Summary (2000)

Figure 5.3 shows the number of poor air quality days recorded at selected cities in Ontario for the period 1996 to 2000.

The figure shows the highest number of poor air quality days was recorded in cities in the southwestern portion of the province. These cities are in closer proximity to the Ohio Valley region and the U.S. mid-west, regions from which ozone and its precursors are transported into southern Ontario.

However, in all of the selected cities except Thunder Bay, the number of poor air quality days recorded in 2000 was lower than the number of poor days recorded in 1998 and 1999. At some of the cities, the number of poor air quality days in 2000 was even lower than the number of poor days recorded over the entire five-year period. Cool and wet conditions prevailed during the summer of 2000, and these conditions were not conducive to the production of high levels of ozone.

AIR POLLUTION INDEX (API)

The air pollution index continues to be the basis of an alert and control system to warn of deteriorating air quality. It is derived from 24-hour running averages of sulphur dioxide (SO₂) and suspended particles (SP) as defined by a measurement known as the coefficient of haze (COH). Research studies have linked respiratory illness to high concentrations of SO₂ and SP.

Figure 5.2: Geographical Distribution of the Number of Days AQI > 49 Across Ontario (2000)

The Ontario Environmental Protection Act (1971) authorizes the Minister of the Environment to order any point source not essential to public health or safety to curtail or cease its operations when air pollution levels which may be injurious to health occur.

If the API reaches a value of 32 (Advisory Level) and, the duty meteorologist predicts a continuation of adverse atmospheric conditions for at least six hours, an Air Pollution Advisory may be issued. Owners of significant sources of pollution are advised to prepare for possible curtailment of operation.

The First Alert Level is reached if the index reaches 50. If at least six hours of adverse atmospheric conditions are forecast, owners of major sources may be ordered to curtail operations. A second alert is issued at an API of 75 and further curtailment may be ordered.

The Air Pollution Episode Level occurs at an API of 100 and owners of all sources not essential to public safety may be ordered to cease operations if atmospheric conditions are not expected to improve for at least six hours.

API summary (1996-2000)

In 1996, Hamilton Downtown was the only API site that reached the advisory level of 32 and this API level occurred on only one occasion. Windsor West, the only site in 1997 that reached an API above the Advisory threshold of 32, recorded an API of 34.

For the years of 1998 to 2000 the Advisory level of 32 was not reached at any of the API sites.

Smog Alert Program

Initiated in the late spring of 1993 as a joint effort between the Ontario Ministry of the Environment (MOE) and Environment Canada (EC), smog advisories, initially called air quality advisories, are issued to the public when widespread elevated air pollution levels due to ground-level ozone (AQI in the poor category) are forecast to occur within the next 24 hours. The smog advisory program covers southern and northeastern Ontario where ozone levels typically exceed the one-hour ambient air quality criterion (AAQC) of 80 ppb.

Figure 5.3: Number of Days with at Least One-Hour of AQI > 49 at Selected Cities Across Ontario (1996 - 2000)

Air Quality Initiative and Enhanced Smog Alert Program

On May 1st, 2000, Ontario's enhanced Smog Alert and Air Quality Index (AQI) program was implemented. This enhanced program provides Ontarians with improved reporting through comprehensive and timely air quality readings and forecasts.

The new Air Quality Ontario Initiative includes:

• a two-level air quality forecast that provides a three-day outlook, a smog watch, in addition to the current 24 hour smog advisory;
• A Smog Watch is called when there is a 50 per cent chance that a smog day is coming within the next three days.
• A Smog Advisory is called when there is a strong likelihood that a smog day is coming within the next 24 hours.
• If a smog day has happened without warning and weather conditions conducive to high smog are forecast to continue for at least six hours, then a smog advisory will be issued immediately.
• the public Web site, www.airqualityontario.com, where current AQI readings, smog forecasts and other air quality information are available;
• direct e-mail smog alerts for anyone who subscribes to the ministry's new smog alert network at the above website;
• increasing the number of air quality index updates from three up to six times a day, Monday to Friday, and four times per day on weekends;
• adding nine communities to the number of municipalities that report air quality data, totaling 34 air quality reporting stations in 28 communities;
• providing 1-800 numbers at which anyone at anytime can get updated information on the air quality (1-800-387-7768 in English and 1-800-221-8852 in French);
• selecting the Windsor, Essex, Chatham-Kent area as a priority area for the initial component of the plan, since up to 90 per cent of smog over this region originates from transboundary emissions.

Figure 5.4 Summary of Smog Advisories Called
(1993 - 2000)

Six of the ten communities added to the reporting system are summer rural AQI sites (i.e., AQI values are reported from these sites only during the smog season) that provide valuable information on smog levels, particularly the role of transboundary pollution and downwind urban impacts. These rural AQI sites are Merlin, Long Point, Simcoe, Grand Bend, Tiverton and Haliburton. They are often exposed to significant transboundary pollution and elevated levels of ground-level ozone. The other four AQI sites, Brampton, York Region, Guelph and Peterborough, allow for better air quality coverage of growing populated areas of the Greater Toronto Area and surroundings.

For the 2000 smog season, Ontarians experienced the least number of smog advisory days since 1993. In 2000, nine smog watches were issued and three advisories covering four smog days. The weather in the summer of 2000 played a dominant role in the air quality. A lack of hot days (temperatures above 30°C) and steady, but near normal, amounts of precipitation resulted in a relatively low occurrence of smog days. In contrast, the hot and dry summers of the previous two years led to the issuance of eight smog advisory days in 1998, and nine such days in 1999. Figure 5.4 summarizes the number of smog advisories issued and number of smog advisory days since the inception of the program in 1993.