27 February 2003
The American Conference of Governmental Industrial Hygienists (ACGIH) has withdrawn diesel exhaust particulates from the Notice of Intended Changes in its 2003 edition of Threshold Limit Value (TLV) list for chemical substances and physical agents.
ACGIH first proposed an exposure limit of 0.15 mg/m3 for diesel particulate matter (DPM) in its 1995-1996 Notice of Intended Changes (NIC). That limit was later lowered to 0.05 mg/m3 (as total diesel particulate matter). In its 2001 NIC, the ACGIH replaced this TLV with a practically equivalent limit of 0.02 mg/m3, expressed as elemental carbon (EC fraction typically constitutes about 40% of the total diesel particulate mass). The proposed carcinogenicity classification for DPM was A2—“Suspected Human Carcinogen”.
The TLVs set by ACGIH are developed as recommendations or guidelines to be used in the practice of industrial hygiene, which establish the maximum ambient concentrations of toxic chemical substances. Formally, they are not legal standards. However, regulatory authorities follow the ACGIH recommendations in their law-making activities.