What Causes Poor Visibility?
British Columbia is defined by the natural beauty of its mountains and coastlines, which are highly valued by residents and visitors alike. However, our view of these scenic vistas can be impaired by
tiny particles (particulate matter) and gases in the air. These appear as haze that reduces the clarity and color of what we see. These particles come from a variety of natural sources such as forest
fires and dust, and human sources such as vehicles and industrial processes.
Reduced visibility is not just an aesthetic issue, as the public often gauges the quality of the air by how good or poor it looks outside. Visibility impairment can affect tourism, air travel, quality
of life, property values, general well being and our wilderness experience. One study estimates that a single poor-visibility event in the Lower Fraser Valley can result in a loss in future tourism revenue
of 9 million dollars. See The Impact of Visual Air Quality on Tourism Revenues in Greater Vancouver
and the Lower Fraser Valley (Environment Canada).
In addition, the very fine particulate matter (PM) that is most effective in reducing visibility (PM2.5) is in the size
range that penetrates deepest into the lungs. Therefore, poor visibility is associated with an increased risk to human health.
Because visibility degradation is the result of many contributing factors, it is not a simple issue to address. Responding
effectively to improve visibility will require research and careful thought. Contributing factors include a wide variety of natural and human-caused sources of particles and gases, particle composition,
chemical transformations, size, concentration, sun angle and relative humidity.
Generally speaking, although measures to reduce emissions have shown an overall air-quality improvement in the Lower Fraser Valley, anecdotal reports from the eastern Lower Fraser Valley and the
Okanagan region indicate the persistent occurrence of poor visibility that is due to air pollution. This illustrates the difficulty of addressing all concerns adequately within even a carefully
designed air-quality-management plan.
In May 2010, the British Columbia Visibility Coordinating Committee held a visibility workshop for representatives of agencies involved in air quality management and assessment. The workshop's goals were to update attendees on the work conducted by the BC Visibility Coordinating Committee and formulate an action plan to bring visibility management into reality. A report on the outcomes of the workshop has been released, entitled Action Plan Priorities Workshop: Summary Report (PDF: 1.14 MB/21 pages).
The New Clear Air BC Initiative
Air quality agencies in British Columbia have launched Clear Air BC, an initiative aimed at improving visibility across the province. It includes:
- Scientific studies on causes of impaired visibility in the Lower Fraser Valley.
- A new website with information about air quality and visibility.
- A pilot project that will test several strategies to improve visibility.
The partners in Clear Air BC are the Ministry of Environment, Metro Vancouver, Environment Canada and the Fraser Valley Regional District. For more information visit the Clear Air BC website.
The importance of visibility is also emphasized in Metro
Vancouver's Integrated Air Quality and Greenhouse Gas Management Plan: the second of the plan's three primary goals
is to "improve
visual air quality".