In addition to tailpipe emission factors, evaporative VOC emission factors from gasoline-fueled engines need to be developed and included in the inventory. The emissions databases described in the next sections contain evaporative emission rates as well as tailpipe emission rates from various off road equipment types. The ARB database is considered one of the most developed and up-to-date compilation of evaporative emissions, however, they are based on California fuel specifications, which can be very different than in other locations.

There can also be emissions associated with the use of the equipment, such as road dust, tire or other wear types, and emissions created by the grinding or crushing of materials. These are estimated on a case by case basis depending upon if the emissions are thought to be significant from the source or activity. Often, these emissions can be small and can be considered negligible but it is important to review and make this conclusion as these emissions from this category may often be overlooked and sometimes can be significant.