Benzene is emitted from activities related to the petroleum and natural gas industry, transportation and to a lesser extent from steel and chemical production.
Cigarette smoke is also a source of benzene.
Benzene is a non-threshold carcinogen and quantifying the associated risk of exposure has proven to be extremely difficult. The Committee proposes that the CWS be a per cent reduction in emissions from base year 1995 to be delivered in a two phase process. Phase 2 of the benzene CWS could then be based on an additional emission reduction goal or on the development of an ambient standard. The Development Committee will determine the most appropriate direction to take for Phase 2 after more information has been gathered and consultations are held. This proposed path has the benefit of achieving actual overall reductions in benzene emissions, while additional data on exposure and risk is being assessed to determine the need for a CWS based on ambient air quality concentration.