Four samples were collected per sampling run following instrument guidelines similar to those described in the particulate matter federal reference method. The remaining samples were exposed to various environmental conditions prior to extraction. The post sampling test conditions were storage temperature, storage time, and open versus closed container. The nitrate values were evaluated by regression analysis for similar environmental conditions. This study suggests that particulate nitrate losses occur if filters remain on samplers for prolonged periodsof time after sampling.
Losses increase as the filters are exposed to increased temperature.
The study suggests that placing filters in closed containers and a cool environment can significantly reduce nitrate losses. The principal objective of the Bakersfield Winter PM Study was to examine the performance of a variety reference and non-reference PM10 samplers and several PM2.5 samplers in an environment and during a season that would challenge any sampler. The integrated sampling was performed every three days. The data taken during the Summer of 1993 will be used to assess the California Air Resources Board's monitoring capability and preview the ambient hydrocarbon patterns. Related Links PM2.5 Home Page - ARB's main web site for dissemination of PM 2.5 information.