The Clean Air Picture
Canadians are becoming increasingly aware of the issues surrounding climate change, air pollution and the quality of air in their communities. Poor air quality can affect our health, our ecosystem and the livelihoods of many in the Fraser Valley, especially in the areas of tourism and agriculture.
Air Pollution and Human Health
Numerous studies show a strong link between inhalable particulate matter (PM<10 micrometres in size) and aggravated cardiac and respiratory diseases such as asthma, bronchitis and emphysema, and various forms of heart disease. A strong correlation exists between high levels of airborne PM10 and increases in emergency room visits, hospital admissions and even death. Children, the elderly and people with respiratory disorders are particularly susceptible.
A report commissioned by the Medical Health Officers of the Lower Mainland health regions concluded that current levels of air pollution in the Lower Mainland affect human health. Although air quality here is better than in many other cities in western North America, there is evidence that air pollution causes illness and death in Lower Mainland residents. The report estimates that air pollution may cause between 15 and 150 premature deaths per year in the Lower Mainland.
In 2002, the BC Lung Association convened a panel of experts, who concluded that current levels of fine particulate matter and ozone can cause adverse health effects in the Lower Mainland. They also concluded that increased exposure to particulate matter along roadways and in high traffic areas, which have been shown in European studies to aggravate health concerns, may be significant.
Air Pollution and our Ecosystem
Air pollutants affect both plants and animals. Plants that absorb pollutants from the air or precipitation (rain and/or snow) often struggle to survive. Airborne chemicals can cause direct damage to vegetation, interfering with plant function and growth. Particulate deposition on vegetation causes physical smothering of leaves, which leads to increased susceptibility to disease, reduced light transmission and decreased photosynthesis.
To calculate deposition, scientists have measured sulphur, nitrogen and heavy metals in vulnerable mosses and lichens, as well as the levels of these substances in the air and precipitation. They are also studying deposition in arctic and alpine areas, which appear particularly susceptible to this problem. Snowflakes take up pollutants as they form and travel; pollutants then accumulate in the snow pack over winter, and are released to streams, soil and the air when the snow melts.
Other contaminants, known as persistent organic pollutants (POPs), are complex substances that do not break down readily and accumulate in the fatty tissues of fish, wildlife and humans. As gases, they can travel very long distances through the air. To address concerns about these impacts, Canada was the first country to ratify the Stockholm Convention on POPs, a global agreement that will reduce or eliminate twelve toxic substances, including PCBs, DDT and dioxins and furans.
Air Pollution and Agriculture
Air pollution can damage plants and produce negative economic impacts to the agricultural sector. These impacts are important in the Fraser Valley, where agriculture is an important industry. Depending on its toxicity, air pollution can also contaminate soil and water. Furthermore, agricultural crops can also be damaged by ground-level ozone; a study of strawberry plants in the Lower Fraser Valley revealed that ozone reduces the number and weight of fruit, resulting in fruit losses as high as 15%. Another study conducted by the University of British Columbia found that ground-level ozone also affects broccoli yields by compromising leaf growth. The severity of damage to broccoli plant leaves was directly related to ozone levels.
Air Pollution and Tourism
Environment Canada surveyed tourists about poor visibility in the Lower Mainland and found that there are significant economic impacts from increased air pollution and reduced visibility. For a single extreme visibility event, the model predicts a future loss of tourist revenue of $7.45 million in the Greater Vancouver area and $1.32 million in the Fraser Valley. These losses are due to poor visibility episodes and can seriously threaten our regional economy, which benefits greatly from tourism.
How Are We Doing?
As we consider the issues affecting our own region, it is and Canada. Research helps to establish various standards helpful to draw comparisons between the Lower Fraser and reference levels so that we can compare regions and Valley airshed and other airsheds across British Columbia measure the effectiveness of our efforts.
Canada-wide Standards for Particulate Matter and Ozone
In 2000, federal and provincial ministers of the environment established Canada-wide Standards (CWSs) for fine particulate matter and ozone to protect human and ecosystem health. This was important for the long-term goal of minimizing the risks that these contaminants pose to human health and the environment. The standards represent a balance between achieving the best possible health and environmental protection, and the feasibility and costs of reduced air pollution that degrades our air quality.
In most areas of Canada, air quality is better than the CWS for particulate matter and ozone, and in the Lower Fraser Valley, we see improvements in summer-time ozone levels.
Particulate Matter in British Columbia
Inhalable particulate matter was formally declared a toxic substance because of its adverse effects on human health. In addition to our efforts to reduce particulate matter, we also work toward an increased understanding of the complicated science that governs such pollutants. There are many variables that influence air pollution, including the type of land use, the local emissions sources, the physical geography of the locale and regional area, and weather and climate influences.
Data collected to the end of 2000 shows that in the Lower Fraser Valley, concentrations of particulate matter are highest in the late summer. Overall, the levels are lower than in the BC Interior. Sometimes weather conditions can influence the length of high particulate matter episodes, but these occur rarely in the Lower Fraser Valley.
While PM levels do appear to be decreasing in parts of BC, they continue to be high enough to warrant concerns about the effect on human health. This is why the development of the particulate matter indicator–which reflects air quality trends of particulate matter–and the planned update of this indicator during 2004, is an important step toward regular monitoring of levels in the Georgia Basin–Puget Sound area.
Health Reference Levels
Usually, air quality is assessed by comparing observed average levels in a region to some guideline or standard, such as the Canada-Wide Standards. Current research shows that there is no safe level (threshold level below which there are no effects) for either ground-level ozone or particulate matter. This means that there are always health impacts from air quality, even in very clean air-sheds. Despite this, reference levels are established for measurement and comparison purposes.
For more information on current scientific information on safe levels of air pollution, see the Environment Canada website.
Managing Our Air Quality
An important part of managing our air quality is taking regular measurements and comparing the results to existing standards and Health Reference Levels.
This work includes keeping track of how many times each year that ground-level ozone and particulate matter exceed Health Reference Levels. These numbers can be used as indicators of how often people may be exposed to air that poses a risk to health. In 2002, smog levels exceeded the Reference Level in the Fraser Valley about 42% of the time for the ground-level ozone pollutant and about 5% of the time for fine airborne particles (PM10).
As shown on the map and the bar graph below, the percent of time Health Reference Levels were exceeded in the Lower was also lower when compared to other regions in Canada, including the Prairies and the Windsor-Montreal corridor.
Yet while the air in the Lower Fraser Valley has improved, there is much work to be done in the future to simply maintain, let alone reduce, pollution levels in the region.
Despite our successes in improving the quality of our air during a period of unprecedented population growth, we must continue our efforts. Health research shows that significant impacts to human health occur even with our relatively clean air. Environment Canada, along with our partners who also manage air quality, continue to work towards improving the quality of the air that we all breathe.
Comparison of the average percent of time smog pollutant Reference show the 10 ecoprovinces of British Columbia, based on Ecoregions of Levels were exceeded in selected Canadian cities and the Fraser Valley. British Columbia, 1993. (Source: BC Ministry of Environment, Lands and Parks, (Source: Environment Canada, 2001) 1999. Air Data and Monitoring System Database)
