Different stonemasonry processes produce different amounts of stone dust. The table below shows the range of respirable crystalline silica dust levels which can be created by various processes when working on stone with a high crystalline silica content. It is based on past HSE measurements of stonemasons’ respirable crystalline silica dust exposure.

The ranges are very wide and which position in the spectrum applies to your specific processes will depend on the number of factors, many of which are listed below.

Factors affecting stone dust exposure 

Factor tending to push exposure towards the lower end of the range Factor tending to push exposure towards the higher end of the range Comments

Process Factors
Hand tool working Stone Type Powered tool working Stone type Working on ‘hard’ stone may release more fine dust when doing hand chiselling work than ‘soft’ stone. But ‘soft’ stone may release more fine respirable dust when cut with a power tool. Which effect applies will take careful judgement. It is a question of knowing your stone.
Low crystalline silica content stone High crystalline silica content stone Note that quartz content does not have to be that high to lead to high silica dust exposures.
Wet working Dry working Pre-soaking stone will reduce emission of dust and should be standard practice. Active wetting, with running water, of cutting/polishing operations is particularly effective. More potential for its use.
Small amount of stone removed Large amount of stone removed The amount of stone removed will be an important factor affecting exposure.
Short term, infrequent, short duration stone working Long term, frequent, and pronged stone working Length of work time has a direct effect on exposure.

Environmental Factors
Large workroom (relative to the number of masons) Small workroom (relative to the number of masons)

Larger, taller rooms tend to have better natural general ventilation.
Segregation of fundamentally dusty processes from less dusty processes No segregation of fundamentally dusty processes from less dusty processes. Too many stonemasonry workshops conduct all masonry processes in the same workroom whether they are dusty or not.

Control Factors
Planned, effective exhaust ventilation Unplanned, ineffective exhaust ventilation. Exhaust ventilation is often far less effective than believed
Vacuuming-off debris from stone being worked Blowing-off debris from stone being worked (with pneumatic exhaust) Brushing is better than blowing but vacuuming is best. Not a common control practice-yet.
Cleaning workroom by vacuum or wet removal Cleaning workroom by dry brushing May not be a big source of exposure but it could be significant and it is unnecessary.
Work overalls made from low dust retention/release cotton fabric. Work overalls made from high dust retention/release cotton fabric Dust on clothing may be quite a significant source.

Note – some factors are more important than others