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Published in Fall 2001
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Tracking air pollution
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CEC begins development of trinational air emissions inventory
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Because air pollution flows across borders, air quality planners need to know the sources of pollution over large areas, spanning state, provincial, and national jurisdictions across the continent. As Paul Miller writes, the CEC is helping in the development of a trinational air emissions inventory.
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By Paul Miller
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| Industrial pollution often affects our health and environment far from its point of origin. |
From southern Ontario to Nova Scotia, the summer of 2001 was one of the smoggiest in eastern Canada in recent years, with air pollution from the Midwest and northeast US contributing to the problem. Rural upstate New York, lying downwind of pollution sources in southern Ontario, also experienced higher than usual levels of smog, in some instances exceeding the old, one-hour US health standard—a level rarely seen outside more populated urban areas.
To the south, haze pollution affects even such a seemingly unlikely area as Big Bend National Park, located in a remote desert setting where the US and Mexican states of Texas, Chihuahua and Coahuila meet along the Mexico/US frontier. Small microscopic pollutants called aerosol particles are the major cause of haze, and they typically come from the burning of fossil fuels in power plants, trucks, automobiles and other combustion sources. A shift in wind direction can bring haze pollution to Big Bend, either from sources located far away in Mexico or in the United States.
Health studies show that ground-level ozone and aerosol particles pose a clear and substantial threat to human health at lower ambient levels than previously thought. In order to address these health threats, as well as to improve scenic vistas across North America, air quality planners must know how much air pollution from combustion sources contribute to these problems. They typically begin this effort by creating inventories of air pollution from all known sources. Because pollution problems are regional and transboundary in scope, air quality planners increasingly need to develop inventories for sources located over large areas, often across state, provincial, and national borders in North America. The CEC Council recognized this when it adopted Council Resolution 01-05 "Promoting Comparability of Air Emissions Inventories" at the Council’s June 2001 meeting in Guadalajara, Mexico.
The CEC air program is now in the beginning stages of developing the basis for a trinational air emissions inventory in North America. The pollutants of concern include carbon monoxide (CO), sulfur dioxide (SO2), nitrogen oxides (NOx), volatile organic compounds (VOCs), and aerosol particles. In addition to these traditional air pollutants, the CEC Council also directed the CEC to include greenhouse gases, such as carbon dioxide. Identifying major sources of greenhouse gases in North America is critically important in addressing climate change when we consider, for example, that Canada, Mexico and the United States collectively contribute more than 25 percent of annual global carbon dioxide emissions.
The CEC’s air emissions inventory initiative will build upon earlier efforts by the CEC in reporting annual releases of toxics in North America, which is based on information collected by each country’s respective pollutant release and transfer register (PRTR). The CEC’s annual Taking Stock report analyzes North American PRTR data to identify major trends, while promoting public awareness of the information within the PRTRs and the ways in which they can be used to protect the environment and public health. The CEC air emissions inventory project will expand upon the Taking Stock experience by looking at the traditional air pollutants as well as greenhouse gases where common data exist in all three countries.
There are a number of practical reasons for developing a trinational overview of air emissions inventories in North America. These include:
- domestic regulatory and statutory planning requirements that involve atmospheric modeling of airsheds across international boundaries and
- the need for sufficiently detailed information that allows planners to focus on where effective and practical reduction targets exist, such as knowing whether emissions arise from combustion or process activities within a facility.
Such an inventory must:
- provide transparent data reporting of comparable quality across the three NAFTA countries that can be used for tracking compliance with possible future North American emissions trading programs,
- allow countries and the public to track criteria air and greenhouse gas emission trends, hence monitor the effectiveness of control measures across North America, and
- provide the public with readily accessible information on air pollutants and greenhouse gases emitted in their local communities or across the continent.
While the level of detail for public reporting is probably sufficient when aggregated by annual emissions from sources, in some cases air quality planners will need more detailed emission inventory information to develop clean air programs. The more detailed inventories are critical inputs to atmospheric models that air quality planners use in developing national programs and strategies. While such detailed data reporting may not be necessary on an annual basis, air quality planners will likely choose certain pollution episode periods spanning a few days to a few weeks in order to model control strategy scenarios. During these periods, they will need specific information on the geographic location of sources, the physical characteristics of stationary sources (e.g., smokestack heights), how pollutants emitted from a source vary with the time of day, and other key parameters necessary for informed planning decisions.
At present, governments treat some types of important air pollution information reported by industrial sources as confidential business information. This makes it difficult for air quality planners in adjacent areas to account accurately for air pollutants from these sources that contribute to their cross-border air pollution problem. The good news is that there is increasing momentum to allow greater access to basic air pollution information that will benefit not only air quality planners, but the public as well. The Fox administration in Mexico, for example, plans to propose legislation this year requiring more mandatory reporting of pollutants by industry in Mexico and to make the information publicly available. Canada is developing new regulations for public reporting of air pollutant emissions from industrial sources by 2003.
Designing effective regional control strategies to address ground-level ozone, aerosol particles, and climate change will require close collaboration among the North American countries to devise a common set of comparable data elements that can be shared across borders. By promoting comparability in air emissions inventories in North America, the CEC can assist in finding solutions to these regional and global problems.
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Paul Miller