Maryland heat stress standard
COMAR 09.12.32 indoor and outdoor heat stress from heat index 80 F, with rest breaks at 90 F and 100 F.
Maryland is unusual in covering indoor and outdoor work under a single heat standard, keyed to heat index. From heat index 80 F you need a written plan, monitoring through the shift, shade or equivalent cooling, and 32 ounces of cool water per hour per exposed worker. Rest scales at 90 F and 100 F, and buildings without mechanical ventilation have to measure directly rather than rely on a weather app.
Takeaways
- Apply one standard to both your indoor and outdoor Maryland sites.
- Say how much water and rest is owed at a given heat index.
- Know when a weather service reading is not good enough.
- Set up training and recordkeeping that satisfies the annual and post-incident requirements.
What heat index 80 F turns on
Rest at 90 F and 100 F
When you have to measure on site
Training, retraining, and what to keep
Frequently asked questions
- Does Maryland cover indoor work? Yes. COMAR 09.12.32 applies to indoor and outdoor work sites where employees are exposed to a heat index of 80 F or above.
- Is 32 ounces per hour really the number? Yes, that is the Maryland figure: at least 32 ounces of cool drinking water per hour per exposed employee, which is a quart. Water has to be readily accessible.
- How long do I keep the records? At least one year for training and monitoring records. Many employers keep them longer, because a citation window can outlast the retention minimum.
- What counts as returning from an absence? Seven or more consecutive days away from heat exposure restarts acclimatization, whether the reason was vacation, illness, or a change in assignment.