Measuring Environmental Impacts – Air
Impacts of Air Emissions from Power Generation:
Smog:
The term "smog" was first coined more than three decades ago to describe a mixture of smoke and fog in the air. Today, "smog" refers to a noxious mixture of air pollutants that can often be seen as a haze in the air. Smog can make breathing more difficult -- even for healthy people -- and it can make us more susceptible to cardio-respiratory diseases. Even healthy young adults breathe less efficiently on days when the air is heavily polluted, especially if exercising outdoors. Particularly vulnerable to smog are people with heart or lung disease, the elderly and small children. The two main ingredients in smog that affect our health are ground-level ozone and fine airborne particles.
Ground-level Ozone:
Ground-level ozone is a colourless and highly irritating gas that forms just above the earth's surface. It is called a "secondary" pollutant because it is produced when two primary pollutants react in sunlight and stagnant air. These two primary pollutants are nitrogen oxides (NOX) and volatile organic compounds (VOC). NOX and VOC come from natural sources as well as human activities. • • NOX are nitrogen-oxygen compounds that include the gases nitric oxide and nitrogen dioxide, and are produced mostly by burning fossil fuels. VOC are carbon-containing gases and vapours such as gasoline fumes and solvents (but excluding carbon dioxide, carbon monoxide, methane, and chlorofluorocarbons).
Health Effects of Ozone: Ozone can irritate lung airways and cause inflammation much like a sunburn. Other symptoms include wheezing, coughing, pain when taking a deep breath, and breathing difficulties during exercise or outdoor activities. People with respiratory problems are most vulnerable, but even healthy people that are active outdoors can be affected when ozone levels are high. Repeated exposure to ozone pollution for several months may cause permanent lung damage. Anyone who spends time outdoors in the summer is at risk, particularly children and other people who are active outdoors. Even at very low levels, ground-level ozone triggers a variety of health problems including aggravated asthma, reduced lung capacity, and increased susceptibility to respiratory illnesses like pneumonia and bronchitis. Ecological Effects of Ozone: Ground-level ozone interferes with the ability of plants to produce and store food, which makes them more susceptible to disease, insects, other pollutants, and harsh weather. Ozone damages the leaves of trees and other plants. Ozone reduces crop and forest yields and increases plant vulnerability to disease, pests, and harsh weather.
Fine Particulates:
Fine particulates are microscopic particles that remain suspended in the air for some time. Fine particulates can be both primary pollutants and secondary pollutants, sent directly into the atmosphere in the form of
Measuring Environmental Impacts - Air
windblown dust and soil, sea salt spray, pollen and spores. Secondary particles are formed through chemical reactions involving NOX, sulphur dioxide (SO X), VOCs and ammonia. Health Effects of Fine Particulates: Many scientific studies have linked breathing fine particulates to a series of significant health problems, including: • aggravated asthma • increases in respiratory symptoms like coughing and difficult or painful breathing • chronic bronchitis • decreased lung function • lung cancer and premature death Ecological Effects of fine Particulates: Fine particulates are the major cause of reduced visibility (haze). Particles can be carried over long distances by wind and then settle on ground or water. The effects of this settling include: • making lakes and streams acidic • changing the nutrient balance in coastal waters and large river basins • depleting the nutrients in soil • damaging sensitive forests and farm crops • affecting the diversity of ecosystems Soot, a type of fine particulates, stains and damages stone and other materials, including culturally important objects such as monuments and statues.
Other Pollutants in Smog:
• • • • Nitrogen Dioxide (NO2 ) is a principal member of the family of nitrogen oxides (NO X ). It is a toxic, irritating gas that results from all combustion processes. Carbon Monoxide (CO) is a colourless, odourless and tasteless gas that comes primarily from automobile emissions. Ammonia is another pollutant in smog. Most fine particulates are either ammonium sulphate or ammonium nitrate. Sulphur dioxide (SO2) is a colourless gas that smells like burnt matches. It can be chemically transformed into acidic pollutants such as sulphuric acid and sulphates (sulphates are a major component of fine particles). Sulphur dioxide is also the main cause of acid rain, which can damage crops, forests and whole ecosystems.
Acid Rain
Rain is naturally slightly acidic (around pH 5) because it contains acids formed when carbon dioxide and chlorine gases react with moisture in the atmosphere. If it has a pH lower than 5, it is considered acid rain. Acid rain is caused primarily by two common air pollutants - sulphur oxides (SO X) and nitrogen oxides (NO X) - that are produced by the burning of fossil fuels. These pollutants can travel thousands of kilometres in the atmosphere, where they mix with water vapour to form a mild solution of sulphuric and nitric acid. Rain, snow, hail, fog and other precipitation wash this solution down to earth as acid rain. Acids can also be transformed chemically into sulphur dioxide gas or sulphur and nitrogen salts that are deposited dry in dust or other particles. The interactions between acid rain, ultraviolet (UV) radiation, climate change and other human-related stresses can magnify their impacts. For example, because acidity reduces the amount of dissolved organic matter in lake water, acidic lakes are clearer and therefore more vulnerable to the effects of increased UV levels. Climate change also affects acid levels in lakes, because hot, dry conditions convert harmless sulphur compounds that have accumulated in wetlands into acid-forming sulphates. When it rains, these sulphates are flushed into surrounding lakes, boosting their acid levels.
SOX:
SOX gases are formed when fuel containing sulphur, such as coal and oil, is burned, and when gasoline is extracted from oil, or metals are extracted from ore. SO2 dissolves in water vapour to form acid, and
2
Measuring Environmental Impacts - Air
interacts with other gases and particles in the air to form sulphates and other products that can be harmful to people and their environment. Health Effects of SOX: SOX in the air can cause temporary breathing difficulty for people with asthma who are active outdoors. Longer-term exposures to high levels of SOX gas and particles cause respiratory illness and aggravate existing heart disease. SO X reacts with other chemicals in the air to form tiny sulphate particles. When these are breathed, they gather in the lungs and are associated with increased respiratory symptoms and disease, difficulty in breathing, and premature death. Ecological Effects of SOX: SO X and NOX react with other substances in the air to form acids, which fall to earth as rain, fog, snow, or dry particles. Some may be carried by the wind for hundreds of miles. Acid rain damages forests and crops, changes the makeup of soil, and makes lakes and streams acidic and unsuitable for fish. Continued exposure over a long time changes the natural variety of plants and animals in an ecosystem. SOX accelerates the decay of building materials and paints, including irreplaceable monuments, statues, and sculptures. Sulphate particles are the major cause of reduced visibility in many areas.
NOX
NOX, is the generic term for a group of highly reactive gases, all of which contain nitrogen and oxygen in varying amounts. Many of the nitrogen oxides are colourless and odourless. However, one common pollutant, nitrogen dioxide (NO2) along with particles in the air can often be seen as a reddish-brown layer over many urban areas. Nitrogen oxides form when fuel is burned at high temperatures, as in a combustion process. Health Effects of NOX: NOX primarily affects breathing and the respiratory system causing damage to lung tissue, and premature death. Small particles penetrate deeply into sensitive parts of the lungs and can cause or worsen respiratory disease such as emphysema and bronchitis, and aggravate existing heart disease. Ecological Effects of NOX: Increased nitrogen loading in water bodies, particularly coastal estuaries, upsets the chemical balance of nutrients used by aquatic plants and animals. Additional nitrogen accelerates "eutrophication," which leads to oxygen depletion and reduces fish and shellfish populations. One member of the NOX, nitrous oxide, is a greenhouse gas. NO X reacts with other substances in the air to form acids, which fall to earth as rain, fog, snow or dry particles. In the air, NO X reacts readily with common organic chemicals and even ozone, to form a wide variety of toxic products, some of which may cause biological mutations. Examples of these chemicals include the nitrate radical, nitroarenes, and nitrosamines. Nitrate particles and nitrogen dioxide can block the transmission of light, reducing visibility
Mercury
Mercury is a liquid heavy metal that can volatize into the air and be carried by the atmosphere all over the world. Mercury is found in many lakes, streams, forests and fields. It can convert to a very toxic and bioaccumulative form known as methylmercury -- a substance that can affect both humans and wildlife. Health Effects of Mercury: Mercury exposure at high levels can harm the brain, heart, kidneys, lungs, and immune system of people of all ages. Research shows that most people's fish consumption does not cause a health concern. However, it has been demonstrated that high levels of methylmercury in the bloodstream of unborn babies and young children may harm the developing nervous system, making the child less able to think and learn. More information Ecological Effects of Mercury: Birds and mammals that eat fish are more exposed to mercury than other animals in water ecosystems. Similarly, predators that eat fish-eating animals may be highly exposed. At high levels of exposure, methylmercury's harmful effects on these animals include death, reduced reproduction, slower growth and development, and abnormal behaviour. More information
3
Measuring Environmental Impacts - Air
Climate Change
Climate change is a shift in the “average weather” that a given region experiences. This is measured by changes in all the features we associate with weather, such as temperature, wind patterns, precipitation, and storms. Global climate change means change in the climate of the Earth as a whole. Global climate change does occur naturally. The ice age is an example. The Earth's natural climate has always been, and still is, constantly changing. The climate change we are seeing today differs from previous climate change in both its rate and its magnitude. The temperature on Earth is regulated by a system known as the “greenhouse effect”. Greenhouse gasses, primarily water vapour, carbon dioxide, methane, and nitrous oxide, trap the heat of the sun, preventing radiation from dissipating into space. Without the effect of these naturally occurring gases, the average temperature on the Earth would be -18° C, instead of the current average of 15°. Life as we know it would be impossible. Over the past 200 years, emissions of these gases due to human activities have accumulated in the atmosphere, where, because of their long life, they stay for anywhere from decades to centuries. As a result, since the Industrial Revolution, concentrations of carbon dioxide have increased by 30 per cent, methane by 145 per cent, and nitrous oxide by 15 per cent. The cause of these increases has been human activities related to our increasingly sophisticated and mechanized lifestyle, in particular the burning of fossil fuels such as coal, oil, and natural gas to generate electricity and in factories and cars. As well, we have cleared more land for human use in the past 100 years than in all of prior human history. This has resulted in the loss of forests and wetlands, which absorb and store greenhouse gases and naturally regulate the atmosphere. In effect, by increasing the amount of these heat-trapping gases, we have “enhanced” the natural greenhouse effect to the point that it has the potential to warm the planet at a rate that has never been experienced in human history. Already, the average global temperature has increased by about 0.5° C in the past 100 years, and temperature increases over the next 100 years are expected to significantly surpass any such change of the past 10,000 years. Raising the global temperature may trigger a series of changes within the overall global climate system. For instance, global sea levels have risen 10-25 cm over the past 100 years, and are expected to continue to rise as the oceans expand due to small increases in temperature. We are also seeing increases in severe weather events. Such impacts of climate change could have far-reaching and/or unpredictable environmental, social, and economic consequences.
4
Measuring Environmental Impacts - Air
Air Emissions Regulation:
Federal
The Canadian Environmental Protection Act (CEPA 1999) is Canada's primary piece of federal pollution prevention and environmental legislation. The Act gives the federal government the tools for protecting the environment and human health, and establishes strict deadlines for controlling toxic substances. Under the Act, a substance may be considered to be toxic if it enters, or may enter, the environment in a quantity or concentration or under conditions that: • have or may have an immediate or long-term harmful effect on the environment or its biological diversity; • constitute or may constitute a danger to the environment on which life depends; or • constitute or may constitute a danger in Canada to human life or health. Eighty-two substances in the 2002 NPRI have been determined to be toxic under CEPA 1999.
Provincial
The Environmental Management Act (the EMA) was brought into force on July 8, 2004. The act replaces the Waste Management Act and the Environment Management Act and brings provisions from both of those acts into one statute. The EMA provides enabling provisions for modern environmental management tools such as area-based planning and administrative monetary penalties. The air emission restrictions of the EMA are similar to those under CEPA.
5
Measuring Environmental Impacts - Air
Generation-specific emissions:
Coal
When coal is burned, carbon dioxide, sulphur dioxide, nitrogen oxides, and mercury compounds are released. The amount of sulphur dioxide and mercury compounds can vary greatly depending on the sulphur and mercury content of the coal that is burned. The average emission rates from coal-fired generation are: 1000 kg/MWh of carbon dioxide, 6 kg/MWh of sulphur dioxide, and 3 kg/MWh of nitrogen oxides. Mining, cleaning, and transporting coal to the power plant generate additional emissions. For example, methane, a potent greenhouse gas that is trapped in the coal, is often vented during these processes to increase safety.
Oil
Burning oil at power plants produces nitrogen oxides, sulphur dioxide, carbon dioxide, methane, and mercury compounds. The amount of sulphur dioxide and mercury compounds can vary greatly depending on the sulphur and mercury content of the oil that is burned. The average emissions rates from oil-fired generation are: 760 kg/MWh of carbon dioxide, 5.5 kg/MWh of sulphur dioxide, and 1.8 kg/MWh of nitrogen oxides.1 In addition, oil wells and oil collection equipment are a source of emissions of methane, a potent greenhouse gas. The large engines that are used in the oil drilling, production, and transportation processes burn natural gas or diesel that also produce emissions.
Natural Gas
At the power plant, the burning of natural gas produces nitrogen oxides and carbon dioxide, but in lower quantities than burning coal or oil. Methane, a primary component of natural gas and a greenhouse gas, can also be emitted into the air when natural gas is not burned completely. Similarly, methane can be emitted as the result of leaks and losses during transportation. Emissions of sulphur dioxide and mercury compounds from burning natural gas are negligible. The average emissions rates from single cycle natural gas-fired generation are: 515 kg/MWh of carbon dioxide, 0.45 kg/MWh of sulphur dioxide, and 0.772 kg/MWh of nitrogen oxides. The average emissions rates from combined cycle natural gas-fired turbine generation are: 360 kg/MWh of carbon dioxide, 0.45 kg/MWh of sulphur dioxide, and 0.350 kg/MWh of nitrogen oxides. In addition, natural gas wells and collection equipment are a source of emissions of methane, a potent greenhouse gas. The large engines that are used in the drilling, production, and transportation processes burn natural gas that also produces emissions.
Hydroelectricity
Hydroelectricity's air emissions are negligible because no fuels are burned and the net greenhouse gas flux in cold deep reservoirs is generally negligible. However, if a large amount of vegetation is growing along the riverbed when a dam is built, it can decay in the lake that is created, causing the build-up and release of methane, a potent greenhouse gas.
6
Measuring Environmental Impacts - Air
Solar
Emissions associated with generating electricity from solar technologies are negligible because no fuels are combusted and no chemical processes are involved.
Geothermal
Emissions associated with generating electricity from geothermal technologies are negligible because no fuels are combusted and no chemical processes are involved.
Biomass
Biomass power plants emit nitrogen oxides, a small amount of sulfur dioxide and potentially dioxins. The amounts emitted depend on the type of biomass that is burned and the type of generator used. Although the burning of biomass also produces carbon dioxide, the primary greenhouse gas, it is considered to be part of the natural carbon cycle of the earth. Plants take up carbon dioxide from the air while they are growing and then return it to the air when they are burned, thereby causing no net increase. Biomass contains much less sulphur and nitrogen than coal; therefore, when biomass is co-fired with coal, sulphur dioxide and nitrogen oxides emissions are lower than when coal is burned alone. When the role of renewable biomass in the carbon cycle is considered, the carbon dioxide emissions that result from co-firing biomass with coal are lower than those from burning coal alone.
Landfill Gas
Burning landfill gas produces nitrogen oxides emissions as well as trace amounts of toxic materials. The amount of these emissions can vary widely, depending on the waste from which the landfill gas was created. The carbon dioxide released from burning landfill gas is considered to be a part of the natural carbon cycle of the earth. Producing electricity from landfill gas avoids the need to use non-renewable resources to produce the same amount of electricity. In addition, burning landfill gas prevents the release of methane, a potent greenhouse gas, into the atmosphere.
Wind
Emissions associated with generating electricity from wind technology are negligible because no fuels are combusted and no chemical processes are involved.
7