The use of compressed air for cleaning purposes at pressures greater than 30 P.S.I. is permissible, if the outlet or source is fitted with a relief device that drops the pressure to less than 30 P.S.I. if the flow is dead ended, according to an OSHA letter of interpretation sent by then- Acting Director,
Federal Compliance and State Programs Bruce Hillenbrand in response to an inquiry.

“Air guns used with long pipes are acceptable, if they meet the requirements of 29 CFR 1910.242(b),” said Hillenbrand.

“The Occupational Safety and Health Act of 1970 contains no provisions allowing approval or endorsement of equipment. Alteration or misapplication of an otherwise safe piece of equipment could easily create a hazardous condition beyond the control of the manufacturer. Statements alleging products have OSHA approval or certification are erroneous. Those that come to OSHA's attention are forwarded to the Office of the Solicitor for appropriate action.”