Table 1

Occupational and environmental exposure limits7–9

*These standards are time weighted averages over 8 hours, and assume a 40 hour working week.
†These limits apply to the ISO convention for respirable dust; the limits that applied using the BMRC convention were 5000 μg/m3for respirable dust and 400 μg/m3for silica.
‡Department for the Environment, Transport and the Regions Expert Panel on Air Quality Standards.
Respirable dust
    HSE†4000 μg/m3800 μg/m350 μg/m3
Crystalline silica
    HSE†300 μg/m380 μg/m380 μg/m3
    ACGIH cristobalite50 μg/m310 μg/m310 μg/m3
    ACGIH quartz100 μg/m3