Air Quality

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Background

Air quality emissions inventories and studies completed on behalf of the BC Ministry of Environment and Climate Change and Cowichan Valley Regional District show that particulate matter less than 2.5 microns (PM2.5) is the main contaminant of concern for the Cowichan Region. PM2.5 is one of the only Criteria Air Contaminants that has historically exceeded provincial air quality guidelines and has human health, environmental, and economic impacts. Table 1 and Figures 1 and 2 below display PM2.5 data in comparison to the provincial air quality objectives.

Table 1 – Provincial air quality objectives for PM2.5.

Air Quality Objectives

Annual Average

Daily Average

Provincial Air Quality Objective

8 ug/m3

25 ug/m3

Figure 1 – A summary of the PM2.5 data from each of the air quality monitoring stations within or adjacent to North Cowichan municipal boundaries.

Note:The substantial increase in wildfire smoke in recent years has increased the overall levels of PM2.5 in the Cowichan Valley.  Prior to 2017, these wildfires did not have a substantial effect on local air quality.  Data from the Crofton and Quamichan monitoring stations prior to 2014 was witheld from this chart as the equipment at these stations was upgraded with more accurate monitoring equipment in 2014.

Figure 2 - Exceedances of Daily PM2.5 Air Quality Objective

Note:  Note:The substantial increase in wildfire smoke in recent years has increased the overall levels of PM2.5 in the Cowichan Valley.  Prior to 2017, these wildfires did not have a substantial effect on local air quality.  Data from the Crofton and Quamichan monitoring stations prior to 2014 was witheld from this chart as the equipment at these stations was upgraded with more accurate monitoring equipment in 2014.

Relevant Information and Studies