Diesel particulate filter (DPF) manufacturer Cleaire Advanced Emission Controls has ceased operations.

The company, which offered a variety of DPFs to retrofit school buses and other vehicles, closed on Jan. 18, according to the California Air Resources Board (CARB).

Robert Cross, chief of CARB’s Mobile Source Control Division, said in a Jan. 25 letter to Cleaire customers that the agency would “work closely with fleets, dealers and parts suppliers to minimize the impact of the Cleaire closure.”

Heavy Duty Trucking (which, like SBF, is a Bobit publication) reports that Cleaire’s closure is apparently due to expensive recalls and brush fires caused by sparks from the company’s DPFs.

The sparking and fire-starting was linked to a metal substrate in Cleaire's LongMile DPFs, according to Heavy Duty Trucking. Officials in Washington state reportedly blamed a September 2011 wildfire on a Cleaire filter on a truck.

A newspaper report from the time said that after the Washington fire, a school district in Humboldt, Calif., placed out of service 17 buses that were equipped with the LongMile filter because of safety concerns with the device.

In September of last year, CARB announced that Cleaire was voluntarily recalling its LongMile DPFs free of charge to owners.

Cross, the CARB official, said in his recent letter that “it is paramount that the safety concerns with the Cleaire LongMile system are immediately addressed.”

The agency said that it has been working to ensure that all LongMile filters are replaced with Cleaire’s CMM product or another compliant product as quickly as possible.

Also, Cross said that the agency would “ensure that fleets are not put in jeopardy of noncompliance with [CARB] in-use fleet rules as a result of these developments, and is working with Cleaire distributors, installers and other authorized representatives so that impacts on warranty service and the availability of replacement parts is minimized.”

CARB has set up a Cleaire information page here.

In August 2011, private equity firm NewWorld Capital Group announced that it had acquired Cleaire. The firm invests in companies in the environmental opportunities sector.