Passive ozone network of Dallas: a modeling opportunity with community involvement. 1

Despite tremendous efforts toward regulating and controlling tropospheric ozone (O3) formation, a large portion of the U.S. population presently lives in environments where air quality exceeds both 1- and 8-h National Ambient Air Quality Standards (NAAQS) set for O3. High O3 concentrations annually cost the United States billions of dollars in excessive human health costs, reduced crop yields, and ecological damage. This paper describes a regional networking of O3 monitoring sites, operated by the public, that used simplified passive sampling devices (PSDs). In collaboration with EPA Region 6, a lay network (i.e., Passive Ozone Network of Dallas, acronym POND), consisting of 30 PSD sites in the Dallas-Fort Worth (DFW) Metroplex, a region representing 16 counties, successfully measured daily ozone during 8 weeks of the 1998 high ozone season. It was demonstrated that the concerned public, when properly trained, could successfully operate a large PSD network that requires daily sample handling and weekly mailing procedures, even from remote sites. Data treatment of the 2880 POND measurements included (i) high correlations with collocated continuous monitoring data [r range = 0.95-0.97], (ii) daily O3 contour mapping of the 24,000 km2 area, and (iii) a ranking of O3 severity in 12 peri-urban counties for guidance in sitting additional monitors. With a new 8-h NAAQS standard now in place, a cost-effective network such as POND could aid regional airshed models in generating meaningful guidance for O3 state implementation plans (SIPs) by providing input that is representative of both rural and urban sites.