Air Pollution in the Province of Quebec during the February, 1998 Stagnation Event

Submitted by Mario Benjamin, Environment Canada - Région du Québec, on 2/2/99

As indicated in Rich's Summary, the large-scale, multi-pollutant event during February 9-13, 1998 was observed over large areas in Southeastern Canada as well as the Northeastern US. The following figures illustrate some of the features of pollution concentrations during this time period in the Province of Quebec. Unusually high concentrations of TSP, PM-10, PM-2.5, NO and particulate nitrate were recorded at many provincial sites, but were especially high in and near the Montreal urban area. On February 10th, maximum Quebec concentrations from routine 6th day filter samples were as high or higher than levels observed at urban centers in the States at sites in or near Montreal, where maximum observed 24-hour concentrations included 170 µg/m³ for TSP, 138 µg/m³ for PM-10, and 28 µg/m³ for particulate nitrate. The continuous measurements of PM-10, PM-2.5 and NO indicate a multi-day build-up similar to that observed at many of the Northeastern US sites, but appear to reach a maximum on February 11th, whereas many of the US sites in Rich's summary (Fig. 3 and Fig 4.) peak a day earlier on February 10th. This time lag and back trajectory calculations for several Southern Quebec sites, suggest that transport from the South, as well as local stagnation may have contributed to the high concentrations observed in Southern Quebec.

Figure 1 displays the PM2.5 continuous measurement from TEOM (2.5 Cyclone heads) for 4 sites in southwestern Quebec.

Figure 2 displays continuous NO measurements (Teco 42S) and PM2.5 measurements at St-Anicet, Quebec, about 60 km southwest of Montreal in a rural aera. The Teco 42S had recorded concentrations greater than 50 ppbV which is off the scale.

Figure 3 displays PM10 continuous measurements from a TEOM (10 µm Cyclone head) at a site located east of Montreal.

Figure 4 shows 24-hour Total Suspended Particulate concentrations at sites in the Province of Quebec on 2/10/98. Data are still in a draft form.

Figure 5 shows 24-hour PM-10 concentrations at sites in the Province of Quebec on 2/10/98. Data are still in a draft form.

Figure 6 shows particulate sulfate measured on TSP filters at sites in the Province of Quebec on 2/10/98. Data are still in a draft form.

Figure 7 shows particulate sulfate measured on PM-10 filters at sites in the Province of Quebec on 2/10/98. Data are still in a draft form.

Figure 8 shows particulate nitrate measured on TSP filters at sites in the Province of Quebec on 2/10/98. Data are still in a draft form.

Figure 9 shows particulate nitrate measured on PM-10 filters at sites in the Province of Quebec on 2/10/98. Data are still in a draft form. For comparaison, 28.0 µg/m3 measured at the southern most site (south of Montreal) constitutes a record for that site. This site is in operation since 1990, and the precedent maximum value was 19 µg/m3 in 1993.

Figure 10 displays the back trajectories computed using Hemispheric Trajectory Model (HTM) and field data from CMC (Canadian Met center). Two levels are shown, 1000 mb and 925 mb.