On 11th December 2008 the California Air Resources Board (CARB) is set to vote on a 12-year strategy requiring diesel trucks to slash emissions. To meet the proposed deadlines older vehicles would need to be retrofitted with pollution filters and eventually replaced with cleaner models by 2020. Any truck weighing more than 6,350kg will be required to have particulate filters fitted. However, fleets consisting of fewer than three trucks will be exempt until 2012. It is remains to be seen what role SCR technology will play, much will depend on the emissions levels set by CARB.