State of the Environment Reports
 

AIR

Air quality in Manitoba generally meets or exceeds all federal and provincial objectives.

Emissions from metal smelters especially at Flin Flon in northern Manitoba have adversely affected local air quality. A new zinc smelter in Flin Flon has reduced airborne particulates and cut sulphur dioxide stack emissions by 25%. Local air quality still is affected adversely by sulphur dioxide emissions.

Areas downwind of metal smelters in northern and eastern Manitoba may be at risk from acid rain damage. Long-term monitoring has shown that precipitation at some stations has become slightly more acidic.

Changes were made to the Ozone Depleting Substances Program in 1994. These include adoption of new regulations and the creation of a nonprofit corporation to assist in phasing out the use of ozone depleting substances in Manitoba.

An intensive study conducted in Winnipeg did not show an association between residential radon levels and increased risk of lung cancer. Although rural radon levels are the highest in the country, they are still below allowable limits set by Health and Welfare Canada.

Flin Flon Air Quality Expected to Improve

In September 1993, Hudson Bay Mining and Smelting Co. Limited (HBM&S) completed an extensive environmental improvement project on the zinc processing portion of its Flin Flon smelter. The goal was to ensure the zinc and copper smelting operation conformed to the more stringent requirements of regulations under The Environment Act. Under the regulations, the company had to reduce sulphur dioxide emissions to 220,000 tonnes per year and airborne particulates to 2,500 tonnes per year by January 1, 1994.

The original zinc smelter, built in the 1930s, was replaced by a zinc pressure leach plant. The new plant uses two stages of pressure leaching to recover 98 to 99% of the zinc in concentrated form. The improvements have reduced sulphur dioxide emissions by approximately 25%. Although there were some initial problems reducing particulate emissions, levels are now below those specified in the regulation.

There has been some improvement in local air quality. However, some episodes of elevated sulphur dioxide still occur, with emissions from the smelter's stack spreading over the community. This happens during weather conditions called surface inversions that force the plume from the smelter stack down to the ground instead of allowing the emissions to disperse. Fugitive spill gases can also have an impact on downtown air quality, although the frequency of these events is decreasing.

A public warning information system is still in operation. Warnings about elevated sulphur dioxide levels are broadcast over local radio. Residents can obtain information on elevated pollution conditions by calling a special telephone number.

Figure 2.1 Flin Flon Sulphur dioxide Monitoring

Respiratory study in the Flin Flon Area

A 1992 study of health care use found a higher incidence of doctor visits and hospitalization for respiratory illness in the Flin Flon area compared to the rest of Manitoba. The Manitoba Health study 32 shows the difference is most significant in young people.

The two-year study compared information on visits to Flin Flon hospitals and doctors' offices with medical visits in the rest of the province. It found:

Hospitalization for respiratory diseases was 30% higher in Flin Flon than in other areas of Manitoba. On average, 39 out of 1,000 people were hospitalized for respiratory disease in Flin Flon, compared with 30 out of 1,000 in the rest of Manitoba.

Differences in rates of hospitalization from other causes were not as large as that for respiratory disease.

In all age groups, the number of patients who visited a clinic for respiratory disease was higher in Flin Flon than in the rest of Manitoba.

The greatest difference in numbers of medical visits was in the five to 29-year-old age group. This group had a 15 to 17% higher rate of medical visits for respiratory diseases than did their counterparts in northern Manitoba. There were approximately 464 doctor visits for every 1,000 people in this age group in Flin Flon, compared to 399 visits per 1,000 in northern Manitoba.

The study indicates a disproportionate amount of respiratory illness among Flin Flon's young people. No higher incidence of cardiovascular disease was found in the Flin Flon population, so the study suggests that smoking alone could not be responsible.

Most Flin Flon residents live within a five-kilometre radius of the HBM&S smelter's stack. Stack emissions contain sulphur dioxide and a fine dust of heavy metals and other chemicals.52 With the recent commissioning of the new zinc plant, stack emissions have been reduced significantly. Monitoring of local air quality continues.

Figure 2.2 Sulphur dioxide Emissions in Manitoba

Reducing Sulphur Dioxide in Thompson

In 1994 sulphur dioxide emissions from Inco Limited in Thompson were 194 kilotonnes, well below the 1994 limit of 220 kilotonnes per year. The company reduced its emissions by rejecting a higher quantity of the iron sulphide mineral (pyrrhotite) from the nickel ore.

Pyrrhotite is a major contributor to the production of sulphur dioxide. However, rejecting more pyrrhotite means losing more nickel to tailings. Higher levels of pyrrhotite in tailings increases the loss of nickel and precious metals while increasing the potential for acid generation. Currently, rejected pyrrhotite is blended with the whole tailings stream. Inco Limited is researching ways of storing the pyrrhotite separately, which could then be recovered from the tailings. If economic markets for sulphur products improve, this may be a valuable product in the future.

To remain viable, the smelting process must target a maximum sulphur-to-nickel ratio. This targeting demands accurate forecasting from the mines and exact metals accounting from the mill and smelter. Options to improve the process and reduce wastage of nickel are being considered. These include:

improving nickel pyrrhotite separation in the mill

reducing sulphur feed to the smelter by shipping copper by-products to other facilities

reducing the quantity of materials that go back to the smelter for reprocessing

researching the production of elemental sulphur from sulphur dioxide

monitoring of sulphur product markets with a view toward providing sulphur products to new customers.

Figure 2.4 Thompson Sulphur dioxide Monitoring, Annual 1-hr. Exceedances

Manitoba Network for Precipitation Collection

Manitoba has been collecting and monitoring precipitation quality since 1980. The Manitoba Network for Precipitation Collection operates three collection sites at Brochet, Island Lake and Pointe du Bois. (see maps (figures 2.8 and 2.9)

The two metallurgical smelters in Flin Flon and Thompson still account for almost 97% of the province's human-caused emissions of sulphur dioxide in the atmosphere. Sulphur dioxide is a pungent, colourless gas formed by the burning of sulphur compounds. It contributes to acid rain, damages vegetation and can raise the incidence of coughs, asthma, bronchitis, emphysema and some non-respiratory diseases. 50

Sensitive Areas in Manitoba

Dust in the atmosphere can have an impact on the chemistry of precipitation. The degree of impact depends on the source of the dust and its alkalinity. Prairie dust is alkaline, with a pH level above the neutral value of 7.0. The alkaline ions of prairie dust neutralize background acidity in precipitation, giving precipitation in most of Manitoba a higher pH level.

However, soil in the area east of Lake Winnipeg and in the northwest corner of the province (which represents approximately 30% of Manitoba) has been identified as being sensitive to acidic inputs. Lakes in the northwest corner of the province are also highly sensitive, while lakes to the east of Lake Winnipeg are moderately sensitive. These areas do not enjoy the buffering benefits of alkaline prairie dust.

Figure 2.5 pH Scale (15K)

Figure 2.6 Volume-Weighted Average pH of Precipitation

Figure 2.7 Acidifying Potential

Brochet is far removed and upwind from the metal smelters located in Flin Flon and Thompson. The average annual pH of the precipitation collected there has ranged from 4.74 to 4.85. Trend analysis through to the end of 1993 indicates that the precipitation at this site is becoming more acidic. From a value of 4.77 in 1991, the average pH was constant at 4.78 for 1993.

Island Lake is downwind of the metal smelters in Flin Flon and Thompson. The average annual pH of precipitation has ranged from 4.42 to 5.09. Trend analysis to the end of 1993 indicates that the pH is gradually rising (becoming less acidic). From a value of 4.72 in 1991, the average pH increased to 5.01 in 1992 and then decreased to 4.94 in 1993.

At Pointe du Bois precipitation with pH levels from 4.87 to 5.28 has been recorded over the past 10 years. Trend analysis through to the end of 1993 indicates that the precipitation is becoming more acidic. In the mid-80s, the yearly averaged pH levels ranged from 5.09 to 5.30. In 1993, the average level was 4.99.

In the Brochet area, the acidifying potential, a relationship between the concentrations of sulphate, calcium and magnesium ions, increased in 1992 and 1993. Sensitive soils and surface waters in the area may be at risk to acidification if these trends for pH and acidifying potential continue in the future.

Over time, the acidifying potential at Island Lake has fluctuated from mildly acidifying to strongly buffering. The years where the net effect was buffering negated some past and future acidifying effects. Due to these periods of buffering, the soils and surface waters are at little to no risk of acidification.

Over time, the acidifying potential at Pointe du Bois has fluctuated from acidifying to buffering. However, the acidifying potential has increased from 1991 to 1993. If precipitation continues to have net positive acidifying potential, then surface waters and soils may be at risk in this area.33 - 36

Figure 2.8: Acidic Input - Lakes

Figure 2.9: Acidic Input - Soils

Climate Change Update

Canada was signatory to the international Framework Convention on Climate Change at the United Nations Conference on Environment and Development held in Rio de Janeiro, Brazil, in June 1992. In December 1992, Canada ratified the Convention on Climate Change, which came into force March 21, 1994. Canadian governments have been working on a national plan to meet the country's international and national obligations. Canada agreed to stabilize greenhouse gas emissions at 1990 levels by the year 2000 and to develop sustainable options to achieve further reductions later.

The development of Canada's plan started in November 1993 when Canadian environment and energy ministers agreed to develop options for greenhouse gas reductions through consultations with interested groups. These options were reviewed by ministers in 1994 and a plan was adopted in early 1995. The National Action Plan on Climate Change was tabled in Berlin at the first meeting of the Conference of the Parties which oversees the framework convention.

Canada's plan sets strategic directions and builds on many initiatives already under way across Canada. The plan will be reviewed regularly to assess progress and adjustments will be made, as required. A voluntary challenge and registry program are important elements of the Plan. Canadian industry, institutions and governments are being asked to take measures that will reduce or offset greenhouse gas emissions.

As part of its continuing effort to consume energy wisely, Manitoba plans to build on its existing programs to improve the efficiency of energy use in the province and to expand the use of renewable energy. Both of these steps will help to reduce greenhouse gas emissions.

Figures 2.10a and 2.10b (12K each) Projected Changes in Ecoclimatic Zones Resulting from a scenario of doubled CO2 climate

Disappearing Down the Sink?

A finite amount of carbon exists on Earth and in the surrounding atmosphere. Carbon is found in the air, vegetation, the oceans, sedimentary rocks and fossil fuels. Anything that stores carbon naturally is referred to as a carbon reservoir. A reservoir that absorbs carbon is known as a carbon "sink". However, at different stages in the carbon cycle, carbon dioxide is released from these reservoirs. When this happens carbon "sinks" become carbon "sources". A balance between carbon storage and carbon dioxide release is essential to the maintenance of a habitable environment for most organisms.

Plants act as carbon sinks because they normally use more carbon dioxide in the photosynthetic process than they release when they respire. Respiration occurs when plants and animals die and decay, releasing carbon dioxide. More carbon dioxide is tied up in sedimentary rocks, fossil fuels and water than in vegetation.

Human modifications of the earth's ecosystems, such as deforestation, have reduced their ability to act as carbon sinks. Deforestation can turn a forest from a carbon sink into a carbon source. 21

Emissions of carbon dioxide and methane from human activities are increasing the concentrations of these gases in the atmosphere and contributing to an enhanced greenhouse effect.

Figure 2.11 Carbon Dioxide Emissions and Sinks

Protecting the Ozone Layer

The Ozone Depleting Substances Act (1990) governs all aspects of sale, use, recovery, storage and disposal of ozone depleting substances.

Nonprofit Industry Association Created

In 1994, a new nonprofit Manitoba corporation known as the Manitoba Ozone Protection Industry Association (MOPIA) was created.

MOPIA's mandate is "to provide information and assistance including leadership, administrative and technical support to all stakeholders in an effort to uniformly phase-out and eliminate the use of ozone depleting substances in the province of Manitoba". 59

MOPIA makes recommendations on certification of technicians and on training programs. It also keeps the service records of the approximately 5,000 certified technicians in Manitoba as well as the sales records of the ODS wholesalers who supply them. These functions were formerly handled by government.

Volunteers from industry, government, educational institutions and the environmental community comprise its membership.

Conforming to the Montreal Protocol

The "Montreal Protocol" is an international agreement to reduce greenhouse gases. The protocol requires that consumption of methyl chloroform cease by January 1, 1996. Consumption is defined as production, import and export.

In keeping with the protocol, Manitoba passed new regulations in 1994 prohibiting the use of all Class One substances, including chlorofluorocarbons (CFCs) and methyl chloroform, after January 1, 1996. Class One substances include 21 different chemicals and chemical groups most harmful to the ozone layer.

The Montreal Protocol also required the use of halons in fire extinguishing equipment to end by January 1, 1994. Two provisions in the new Manitoba regulations relate to the phase out of halons. They prohibit the recharging of hand-held fire extinguishers with ozone depleting substances and the sale of any fire extinguishing equipment containing halons, except for essential uses.

The regulations also require technicians to test for leaks before recharging or top- ping-up air conditioning equipment. This includes automotive air conditioning units. If a leak is revealed, it must be repaired before recharging or topping up.

OZONE DEPLETING SUBSTANCES

Chlorofluorocarbons (CFCs) were first developed in the 1920s . Besides their use as refrigerants in refrigerators and car air conditioners, they were used as propellants in aerosols, in packaging, insulation and other foams; as solvents in degreasers and cleaners; and as blowing agents to produce foams.

When CFCs were identified as an ozone depleting substance in the late 1970s, aerosols became the main target of public action. In 1990, Canada prohibited the use of CFCs in most aerosol applications.

Halons are used mostly in fire extinguishers. Although halons do not present a direct hazard to people, they have a very high potential for ozone depletion.

Carbon Tetrachloride has been used in fire extinguishers, as a dry cleaning agent and as an ingredient in pesticides, pharmaceuticals, paints and solvents. Because of its toxicity, virtually all of these uses have stopped.

Methyl Chloroform, also known as 1,1,1-trichloroethane, is used as a solvent in cleaners, degreasers and adhesives. It first appeared as a substitute for carbon tetrachloride in the mid-50s and by the 1980s was widely used by manufacturing industries. Consumption of this chemical is dropping rapidly.

Hydrochlorofluorocarbons (HCFCs) have a much lower ozone depleting potential than CFCs. They are a transitional chemical, used to replace CFCs. However, they are still considered ozone depleting substances and will also be phased out of consumption.

Methyl bromide was recognized as an ozone depleting substance in 1992. It is a pesticide not manufactured in Canada, but registered for use here. Methyl bromide is used for soil fumigation and space fumigation of some food production facilities. It is also used in some transportation and quarantine applications related to the import and export of agricultural products.

Figure 2.12 How Ozone Depleting Substances Destroy Stratospheric Ozone

INDICATORS OF AIR QUALITY

The province has monitored key pollutants at several urban locations since 1970. Levels of ground-level ozone, nitrogen dioxide and suspended particulates provide a good indication of the quality of air in urban centres. Cool damp summers in southern Manitoba in 1992 and 1993 may be responsible for reduced levels of ground level ozone and suspended particulates. The ban on the sale of leaded gasoline in 1990 has resulted in reduced lead levels in urban air. Only two monitoring stations monitoring in southern Manitoba are still collecting data on this pollutant.

Figure 2.13 Lead

Figure 2.14 Ground-Level Ozone

Figure 2.15 Nitrogen Dioxide

Figure 2.16 Suspended Particulates

Winnipeg Radon Study Shows No Increased Cancer Risk

After Winnipeg was identified as having the highest indoor radon levels of 18 Canadian cities,66 researchers launched a large-scale study of lung cancer in relation to radon exposure in Winnipeg homes. Following seven years of case-control research, Health and Welfare Canada could find no association between residential radon and risk of lung cancer.37

Radon is an odourless, colourless gas that is formed by the radioactive decay of radium and uranium. Uranium miners exposed to exceptionally high levels of radon gas are subject to increased lung cancer risk. The International Agency for Research on Cancer has confirmed radon as a human carcinogen.

Radon Gas: A Natural By-product

Since radium and uranium are present in groundwater, rocks and soil (especially the clay soils of Manitoba), radon gas occurs naturally. It seeps into buildings through cracks in the foundations or through drainage systems. Health and Welfare Canada suggests remedial action if average annual levels exceed 800 bequerels per cubic metre. A bequerel is a standard unit for measuring radiation intensity.

In the Winnipeg homes monitored for the case-control study, the average radon level was about 120 bequerels per cubic metre in the bedroom and 200 bequerels per cubic metre in the basement.

Case-Control Methodology

Cases of lung cancer in Winnipeg residents aged 35 to 80 years were identified through the provincial cancer registry. For each case, a "control" (someone of the same age and gender, but cancer-free) was selected at random from the Winnipeg telephone directory.

In total, 738 case-control pairs were studied from 1983 to 1990. The protocol for the study called for the monitoring of radon in all Winnipeg homes the study subjects had lived in for at least one year.

Research Results Reassuring

Because cigarette smoking and occupational hazards are strong risk factors for lung cancer, it was necessary to adjust for both when estimating odds ratios for lung cancer and radon. After doing so, no association between residential exposure to radon and risk for lung cancer was detected in the findings.

The study was one of the first to attempt the monitoring of radon levels in as many of the homes previously occupied by the study subjects as possible. Other case-control studies restricted radon measurement to one home per subject. The study results are encouraging, given the high indoor radon levels in Winnipeg.

Record Radon Levels in Rural Homes

However, radon levels measured during a province-wide survey conducted by Manitoba Environment in 1990 were three times higher than those observed in the Winnipeg study in 1980.92 The highest concentrations were found in Dauphin where basements averaged 611 bequerels per cubic metre.

It is not difficult or expensive to reduce residential radon levels. Check valves for drains can reduce radon by about 30%. The basement walls and floor can be sealed. A fan can be installed to draw radon-laden air from under the slab and exhaust it outdoors. To reduce indoor radon levels in the future, changes have been made to the Manitoba Building Code to incorporate radon control measures in new homes.

TRENDS

Flin Flon air quality_______Same

Sulphur dioxide emissions from the HBM&S operation have been reduced by about 25% as of September 1993 when the new zinc pressure leaching plant was commissioned. There has been some slight improvement in air quality, primarily in the number of times the one-hour Maximum Acceptable Level of sulphur dioxide has been exceeded.

Global climate change programs_______Same

Manitoba is participating in the development and implementation of a national plan to stabilize greenhouse gas emissions at 1990 levels by the year 2000.

Ozone layer protection_______Same

Manitoba continues to enforce legislation to control the release of ozone depleting substances. Amendments to the Ozone Depleting Substances Regulation were made in 1994, which closed loopholes or clarified certain areas. An industry support association, the Manitoba Ozone Protection Industry Association Inc. (MOPIA), was created to provide training, education and technical assistance.

Acid rain_______Same

Unlike portions of eastern Canada where acid rain continues to be a problem, Manitoba is not experiencing these conditions. Although averaged annual pH levels are acidic, net deposition varies between being slightly acidic to alkaline.

Ground-level ozone concentrations_______Same

Manitoba continues to be an attainment area within Canada-which means levels of ozone seldom exceed provincial air quality objectives. Ground-level ozone has been measured for about 20 years. Levels have fluctuated, except for recent years where an improving trend seems to be developing. This might be associated with recent cool and damp summers.