On June 4 and 5, 2009 PEI and NATSO, the trade association which represents travel plazas and truck stops, co-sponsored a conference on diesel exhaust fluid (DEF).
Diesel exhaust fluid will be required, beginning in 2010, for the exhaust systems on most new diesel trucks which will utilize selective catalytic reduction (SCR) as an emissions control technology. DEF is a urea-based mixture which is specially formulated for use in the new emissions systems.