PM10 levels in the Lower Fraser Valley, British Columbia, Canada: An overview of spatiotemporal variations and meteorological controls

Three years of hourly averaged PM10 (particulate matter less than 10 mu m i n diameter) tapered element oscillating microbalance (TEOM) data from 10 si tes in the large coastal valley incorporating Greater Vancouver were used t o investigate the spatiotemporal dimensions and air pollution meteorology o f particulate pollution. During the period studied, the provincial "accepta ble" objective daily concentration of 50 mu g m(-3) was exceeded at 7 of th e 10 sites. The highest annual, seasonal, and maximum hourly concentrations were recorded at Abbotsford in the central valley. Mean seasonal PM10 conc entrations were highest in the wintertime in the western Lower Fraser Valle y (LFV) and in the summertime at the central and eastern valley locations. Within the network, interstation correlations of daily average concentratio ns exceed 0.8 at interstation distances less than 20 km and decrease therea fter. For daily maximum concentrations (hourly), interstation correlations decrease sharply with distance. Meteorological conditions responsible for e levated particulate concentrations in the LFV are associated with (1) short periods (1- to 3-hr duration) of reduced dispersion during summer nights a t sites close to primary sources, (2) summer anticyclonic conditions when p hotochemical pollutant concentrations build up across the entire valley, an d (3) occasional wintertime "gap wind" events in the eastern valley.