Early this February OSHA shared a publication outlining the five major hazards found in the tree industry. Listed among them were drop zones for falling objects, traffic control, power lines, chippers and Ariel lifts.
Click to view original Tree Care Hazard publication
The publication charts out these five major topics and shares with the reader; the risk factors, identified causes of injuries and fatalities, and tips for prevention.
At this time there is no specific OSHA standards for those employed in the tree care industry. It is often considered to be covered under the general industry requirements or general duty clause, Section 5(s)(1). Individual can also refer to the ANSI Z133.1 standard which addresses safety requirements for arboriculture industry.
Direct link to OSHA's "Solutions for Tree Care Hazards" publication: https://www.osha.gov/Publications/OSHA3940.pdf