A preliminary report is available which presents an updated version of the Maximum Incremental Reactivity (MIR) and other reactivity scales which has been developed using a new version of the SAPRC chemical mechanism. The scales were calculated essentially the same approach and airshed scenarios as used previously (Carter, 1994a), except that the chemical mechanism has been completely updated, many new classes of VOCs have been added. Estimates of relative uncertainties and upper limit reactivities are also presented.

This report can be downloaded as a Portable Document Format (PDF) file, which requires at least the free Acrobat PDF reader to be viewed and printed.

The reactivity scales presented in this report have been developed for use by the California Air Resources Board (CARB) for various regulatory applications. The initial application is expected to be a proposal to incorporate reactivity-based adjustments in some VOC content standards for consumer products. In these regulations, it is proposed that "best estimate" MIR's will be used when determining baselines for product categories, and that "uncertainty adjusted" MIR's will be used when determining whether a product is in compliance with the reactivity-adjusted standard. Therefore, this report includes tabulations of both the "best estimate" and "uncertainty adjusted" MIRs, along with related VOC-specific information relevant to uncertainty and the status of the mechanism employed. This includes reactivities calculated using other scales, indications of generally how the VOC was represented in the model, and footnotes indicating the status and uncertainty of the mechanism and reactivity estimates for the various VOC classes. Reactivities of selected mineral spirits and exhaust mixtures are also given.

Details documenting the updates to the general mechanism, the development of the mechanisms for the new classes of VOCs, and the development of the new reactivity scales will be given in reports which are in preparation (Carter, 1998; Carter et al, 1998). It should be recognized that although the mechanism and reactivities presented in this preliminary report are intended to be the completed versions, the possibility that corrections or adjustments may be appropriate before the mechanism and scales are finalized cannot be ruled out. Therefore, these results must be considered to be preliminary.

This report updates the previous reactivity tabulation which was generated using a previous version of the mechanism. The current version of the updated mechanism is still being evaluated, and is not yet available for downloading.

The files listed below contain the VOC reactivity data calculated using the SAPRC-90 mechanism (and used in the CARB CF/LEV regulations) and the SAPRC-93 mechanisms. These give the data for other scales besides MIR, as discussed by Carter (1994).

Send comments or questions tocarter@cert.ucr.edu

Last Modified September 8, 1998 (September 14, 1999)