This procedure outlines the basic field operation steps for sampling of ambient air at permanent monitoring sites and roadside locations. The air pollutants assessed at each site or location are PM10 and PM2.5. Thermo-Andersen SSI PM10 samplers will be used at the permanent sites and Airmetrics MiniVol PM10 samplers will be used at the roadside locations to collect PM10. ARA N-FRM PM2.5 samplers and UC Boulder QA samplers will be used at continuous monitor sites (and Dansoman) to collect PM2.5 on both 47mm Teflon and 47 mm and 25 mm quartz filters (for QA samplers only). Refer to sample preparation SOP for details on sample preparation prior to field activities. The following procedures are to be used by field operators.