Air pollutant monitoring for the East Bay Children's Respiratory Health Study

Singer, Brett C. ; Hotchi, Toshifumi ; Hodgson, Alfred T.

Lawrence Berkeley National Laboratory

关键词: Nitrogen Oxides;    Particulates;    Chronic Exposure;    Monitoring;    Carbon Monoxide;   

DOI  :  10.2172/816068
RP-ID  :  LBNL--51707
RP-ID  :  AC03-76SF00098
RP-ID  :  816068

美国|英语

来源: UNT Digital Library

【 摘 要 】

This report describes the methodology and presents the summary results of the air pollutant monitoring program conducted by Lawrence Berkeley National Laboratory in support of the East Bay Children's Respiratory Health Study. The full study is examining the effects of chronic exposure to traffic-related pollutants on respiratory health among 3rd and 4th grade children attending ten neighborhood elementary schools in the San Francisco East Bay Area (Hayward, San Leandro and Oakland, CA). The demographically similar schools are located at varying distances from the I-880 and CA-92 freeways. Several schools were selected because they are located within 300 m in the predominant downwind direction (east) from either of the freeways. Measurements of multiple pollutants were made outdoors at the schools over 1-2 week intervals for 14 weeks in spring and eight weeks in fall 2001 using a custom-designed and validated package of commercially available monitoring equipment. Particulate matter was sampled over all hours (24 h per day) or during schools hours only with battery-operated programmable pumps and inlet devices for PM{sub 10} and PM{sub 2.5}. These pumps were modified to allow for up to 10 days of continuous operation. Fine particle mass and black carbon (BC) were determined from the collected filters. Nitrogen oxides (NO{sub x} and NO{sub 2}) were measured with passive samplers. Carbon monoxide (CO) was measured continuously with an electrochemical sensor. Gasoline-related volatile organic compounds (VOCs) were measured with passive samplers during three 4-week intervals in spring 2001 and two 4-week periods in early 2002. All samplers were deployed in a metal cabinet located outside at each school. Ranges of study average pollutant concentrations (all-hours) at the ten individual schools were: NO{sub x}, 33-68 ppb; NO{sub 2}, 19-31 ppb; PM{sub 10} mass, 27-32 {micro}g/m{sup 3}; PM{sub 2.5} mass, 12-15 {micro}g/m{sup 3}; and BC associated with PM{sub 2.5}, 0.6-1.0 {micro}g/m{sup 3}. Although statistical analysis of the data is yet to be performed, some general observations can be made. Absolute pollutant levels varied by season and week, but the simultaneous sampling design allowed for comparisons of concentrations among schools during each interval. Pollutant concentrations at each school were normalized to the sampling period averages among all schools. The normalized concentrations were generally consistent at each school throughout the entire study, suggesting that measured differences represent ongoing conditions and chronic exposures in the vicinities of the schools. Substantially elevated concentrations of NO{sub x}, NO{sub 2}, and BC, and somewhat elevated concentrations of PM{sub 2.5} were observed at one school located less than 100 meters to the east of I-880. Normalized concentrations of NO{sub x}, NO{sub 2}, and BC were also higher at the three other ''nearby and downwind'' schools relative to those located far from any freeway or other major traffic source. An ancillary monitoring program was implemented to examine the correlation between school-based pollutant measurements and measurements throughout the neighborhoods adjacent to three of the schools. Volunteer households were obtained from among the families of participating schoolchildren. Concentrations of NO{sub x} and NO{sub 2} were measured with passive samplers outside the homes of these volunteers during one of two 1-week periods in spring 2002. Simultaneous measurements were conducted at all ten of the schools and a central monitoring station during each week. The neighborhoods surrounding two schools were predominantly upwind of the I-880 freeway, while the neighborhood surrounding the other school was downwind from I-880. The overall distribution of concentrations observed for the residences near the downwind school appeared to be substantially higher than the regional background concentrations. The variability observed within the neighborhoods appeared to be, at least in part, explained by the proximity of individual residences to the freeway or other local traffic sources. Results from the neighborhood study generally support the use of school-based concentration measurements to characterize differences among outdoor exposures in different neighborhoods.