the amount of aromatics (most particularly benzene) in gasoline. Types of virgin naphthas The table below lists some typical virgin heavy naphthas, available for catalytic reforming, derived from various crude oils. It can be seen that they differ significantly in their content of paraffins, naphthenes and aromatics: Cracked naphthas Some refinery naphthas also contain some olefinic hydrocarbons, such as naphthas derived from the fluid catalytic cracking, visbreakers and coking processes used in many refineries. Those olefin-containing naphthas are often referred to as cracked naphthas. In some (but not all) petroleum refineries, the cracked naphthas are desulfurized and catalytically reformed (as are the virgin naphthas) to produce additional high-octane gasoline components. Other uses Some petroleum refineries also produce small amounts of specialty naphthas for use as solvents, cleaning fluids and dry-cleaning agents, paint and varnish diluents, asphalt diluents, rubber industry solvents, recycling products, and cigarette-lighter, portable-camping-stove and lantern fuels. Those specialty naphthas are subjected to various purification processes which adjusts chemical characteristics to suit specific needs. Specialty naphtha comes in many varieties and each are referred to by separate names such as petroleum ether, petroleum spirits, mineral spirits, paraffin, benzine, hexane, ligroin, white oil or white gas, painters naphtha, refined solvent naphtha and Varnish makers' & painters' naphtha (VM&P). The best way to determine the boiling point and other compositional characteristics of any of the specialty naphtha is to read the Safety Data Sheet (SDS) for the specific naphtha of interest. Safety Data Sheets can be found on a chemical suppliers websites or by contacting the supplier directly. On a much larger scale, petroleum naphtha is also used in the petrochemicals industry as feedstock to steam reformers and steam crackers for the production of hydrogen (which may be and is converted into ammonia for fertilizers), ethylene, and other olefins. Natural gas is also used as feedstock to steam reformers and steam crackers. Safety People can be exposed to petroleum naphtha in the workplace by breathing it, swallowing it, skin contact, and eye contact. The Occupational Safety and Health Administration (OSHA) set the legal limit (permissible exposure limit) for petroleum naphtha exposure in the workplace as 500 ppm (2000 mg/m3) over an 8-hour workday. The National Institute for Occupational Safety and Health (NIOSH) has set a recommended exposure limit (REL) of 350 mg/m3 over an 8-hour workday and 1800 mg/m3 over 15 minutes. At levels of 1100 ppm, 10% of the lower