We have a lot of safety rules in construction and it’s practically impossible to monitor your job site for compliance of every single rule.  To complicate matters, many rules are based upon exposure limits, especially when airborne particles are involved.  OSHA recently reduced the allowable exposure limit of silica dust, which is found in concrete, stone, and brick, before additional PPE or engineering controls are required.  This rule change has caused a lot of grief among construction industry groups, who called the rule technologically infeasible, because what contractor is really set up to measure when 50 micrograms of silica dust per cubic meter of air is actually reached?