Pl.go thru' the discussions on the subject in this link-
For further read-
I was working with National Institute of Miners' Health/NI Occupational Health, NEERI, these institutes conduct studies in units especially mining/industry related where finer silica content particles are inhaled by workers engaged therein who are prone to 'silicosis' a dreaded lung disease, not curable, some sort of TB like. Similarly in sand/shot blasting such conditions prevail which may be the cause for this ban wherever imposed. You may take a view after going thru' relevant info. May be you should contact these institutions for an on-the-spot survey to ascertain the conditions are within the tolerable levels and so on. Pl.let me know what is the operation of yours involving this process. Let me also search for articles published by these institutes relevant to your type of process.
26th March 2019 From India, Bangalore