L Preller et al. Occup Environ Med. (2010) Vol.67 p 657-663
Occupational exposure to silica and lung cancer risk in the Netherlands
The current WEL for crystalline silica is 0.1 mg.m-3; equivalent to 4.5 mg.m-3.years for a working lifetime of 45 years. In 1993 HSE estimated that > 90,000 UK workers were exposed to levels in excess of this.