Respiratory protection fourth most-cited OSHA standard

1926.451 – Scaffolding

1926.501 – Fall Protection

1910.1200 – Hazard Communication

1910.134 – Respiratory Protection

1910.147 – Lockout/Tagout

1910.305 – Electrical, Wiring Methods

1910.178 – Powered Industrial Trucks

1926.1053 – Ladders

1910.303 – Electrical, General Requirements

1910.212 – Machine Guarding

Source: Most Frequently Cited Federal Standards, Oct. 2010 to Sept. 2011