# Directives
1 - National - STD 01-12-001 [STD 1-12.1] - Defining Acceptable Guarding of Fan Blades
# Regulations
1 - 1910.212(a)(5) - General requirements for all machines.
# Standard Interpretations
1 - 1910.212(a)(5) - Maximum permissible guard openings for blade guards on cooling fans
2 - 1910.212(a)(5) - Restricting fans to low speed does not void machine guarding standards.