Mobile sources critical review: 1998 NARSTO assessment

Direct observations of daytime NO3: Implications for urban boundary layer chemistry

“…[38] While the reactions of NO with peroxy radicals are practically the only source of O x in the troposphere (direct NO 2 emission is mostly negligible [Kurtenbach et al, 2001;Sawyer et al, 2000]), there are many different sinks. Here we investigate how much the observed daytime NO 3 contributed to the loss of O x at La Porte.…”

Science and uncertainty in environmental regulation: insights from the evaluation of California’s Smog Check program

“…In addition to ermsslons measurements, regulator 3, agenmes rel) on ermssmn factor models to esttmate the emIssmn contribution from mobde sources EPA uses the series of MOBILE models Cahforma uses its own series called EMFAC A complete &scus-stun of the critiques and hmttatmns of these models is beyond the scope of ttus paper, but numerous studaes have ~awn attentmn to flaws m them Crmclsms mclude underestmaatmg on-road vehIcte enussmns, poor representatmn of tugh ermtters, and poor modeling of evaporatwe emass~ons (for more detailed discussion of enuss~on factor models, see Fuj~ta et al, 1992, GAO, 1997, Harley et al, 1997, Pollack et al, 1999~ NRC, 2000. Sawyer et al, 2000 Desplte these criticisms, Mates are reqmred to use an approved ermsslon factor model m their SIPs to demonstrate the ermssmn reductmns that ,~U be actueved by an I/M program (USEPA_ 1992) Both enussmns measurements and enuss~on factor models were an invaluable source of mformat~on used by the groups m the evaluatmn process Inspectmn and rnamtenance program evaluataon is an ac-V.ve area of research and there ts no single accepted method for the evaluatmn of a program hke Smog Check II (USEPA, 1998, Coordinating Research Council, 2000 As was mentioned earlier, both the ARB and/MRC completed evaluatmns of the Smog Check II program Table 3 shows elements that were m each of the reports, including data that were used, evalua~aon goals, and the treatment of uncertainty Each of the evaluatmn reports &scussed the tmcertamtaes and lnmtations m the available data, and, m each, the agency ldenttfied how ,t was planning to respond to, and manage, these tmcertamt~es The two styles were qmte different The IMRC report de&-eared several pages, and spent a great deal of ttme m pubhc meetings, chscussmg the tmcertamtaes and complexaUes m evaluating an I/M program In the face of this uncertainty, IMRC stated that it prowded "a range of benefit esttmates that reflects the tmcertamty inherent m estmaatmg tons-per-day emission reduct,ons'" (IMRC, 2000) On the other hand, ARB bnefl!¢ discussed uncertamDes m the data sources and then selected one type of data on which to base zts analysts, stating that at was using the "best available data from a real world standpoint" (ARB.…”

An Efficient Multipollutant System for Measuring Real-World Emissions from Stationary and Mobile Sources

“…The test cycles are intended to represent real-world operating patterns, but real-world emissions are more variable (Sawyer et al, 2000;Yanowitz et al, 2000;Cocker et al, 2004). Despite their recognized limitations, a limited number of certification measurements are often the only ones available for constructing emission estimates (Chow, 2001;Lloyd and Cackette, 2001).…”