The California Air Resources Board has approved a formula that California employers can use to compare the clean-air benefits of ridesharing and other pollution-reduction programs.

The simple mathematical formula, developed in response to state legislation, will aid employers in developing programs that reduce air pollution and best meet the needs of the company and its employees. The formula should be an especially valuable tool for large employers operating at multiple sites throughout the state.

"For the first time, we have a formula that helps employers anywhere in the state to compare the benefits and costs of ridesharing and other pollution-cutting measures," Air Resources Board Chairman John D. Dunlap said. "This will better enable employers to achieve the biggest reductions in pollution at the least cost."

A number of local air districts in California require major employers to operate employee-ridesharing programs. Three districts -- South Coast, Bay Area and San Joaquin Valley -- allow employers to take alternative measures that result in equal or greater reductions in air pollution. Common alternative measures are repair or scrappage of high-polluting vehicles, purchase of alternative-fuel buses, and retrofitting of cars and trucks to operate on alternative fuels.

Employers contemplating an alternative measure can use the ARB-approved formula to easily determine the emissions reductions accruing from the intended reduction in employee trips under a ridesharing program. Employers can then compare the emissions reductions from the ridesharing and alternative programs.

Assembly Bill 2358 (Sher), approved in 1994, required the Air Resources Board to develop a standard formula for calculating emissions reductions from ridesharing programs. Large employers located at multiple sites in different air districts can use the formula for all of their facilities.