title: A reevaluation of carbon monoxide: past trends, future concentrations, and implications for conformity "hot-spot" policies.
abstract: Control of CO is one of the great air-quality management success stories of the past 20 years. This paper evaluates whether past progress will continue into the future and whether changes in microscale CO concentrations are comparable to reductions observed at the regional scale. Neighborhood and microscale CO concentrations were evaluated at six northern and southern California monitoring sites. The study also included a review of CO emission, concentration, and exposure trends and on-road motor vehicle-based CO emission control programs for California and the United States. Consistent with California and national trends, CO concentrations declined at each of the six study locations from 1988 through 1998. Microscale concentrations declined at the same rate as did neighborhood-scale concentrations. Rollback analyses demonstrated that microscale concentrations will continue to decline through at least 2010-2020. Within a few years, microscale violations of the CO National Ambient Air Quality Standards (NAAQS) will be unlikely in California except under extraordinary circumstances.
authors.affiliation: University of California-Davis/Caltrans Air Quality Project, Department of Civil and Environmental Engineering, 95616, USA. doug@sonomatech.com
authors.forename: Douglas S
authors.initials: DS
authors.lastname: Eisinger
authors.forename: Kellie
authors.initials: K
authors.lastname: Dougherty
authors.forename: Daniel P Y
authors.initials: DP
authors.lastname: Chang
authors.forename: Tom
authors.initials: T
authors.lastname: Kear
authors.forename: Pamela F
authors.initials: PF
authors.lastname: Morgan
mesh_terms: D000393:Air Pollutants / Q000032:analysis*; D002248:Carbon Monoxide / Q000032:analysis*; D004784:Environmental Monitoring; D005544:Forecasting; D017408:Guidelines as Topic; D008962:Models, Theoretical; D013048:Specimen Handling; D014186:Transportation
chemical_list: D000393:Air Pollutants; D002248:Carbon Monoxide