What 29 CFR 1910.136 requires (plain English)
29 CFR 1910.136 requires protective footwear in general industry wherever there is a danger of foot injuries from falling or rolling objects, from objects piercing the sole, or where footwear will protect against an electrical hazard, such as static-discharge or electric-shock, that remains after other protective measures. It is applied with the PPE hazard-assessment duty in 1910.132.
Modern protective footwear is certified to the ASTM F2412 (test methods) and F2413 (performance requirements) standards, which replaced the older ANSI Z41 standard OSHA originally referenced; OSHA recognizes footwear meeting the current ASTM standards or the earlier ANSI edition. Footwear can be rated for impact and compression (safety toe), puncture resistance (a puncture-resistant plate), metatarsal protection, and specific electrical properties: electrical-hazard (EH) rated to resist shock, conductive (CD) to dissipate static where a spark is dangerous, or static-dissipative (SD).
Because the electrical properties are opposites, EH insulates while conductive footwear intentionally drains static, the correct rating depends entirely on the hazard, and the two must not be confused. The employer selects footwear from the 1910.132(d) hazard assessment. Notably, OSHA's PPE payment rule does not require the employer to pay for non-specialty safety-toe footwear (or ordinary prescription safety eyewear) when the employer allows it to be worn off the job site.