Although there is an OSHA Silica Standard, this only applies to workers based on an 8-hour workday.

In non-occupational situations, as in a residential area or community, this obviously is not adequate to protect individuals since the potential exposure can be 24 hours per day, 7 days a week, 365 days a year.

Accepting the fact that silica has been identified as a cancer causing substance, the concern is well justified.  There are many residential areas/communities where the potential for exposure to silica is real.