Heat illness rules for outdoor service crews: the federal status, California and Maryland
What are the heat illness rules for outdoor service crews?
There is no final federal heat standard. OSHA published a proposed rule on August 30, 2024, held a public hearing through July 2, 2025, and post-hearing comments closed October 30, 2025. California and Maryland enforce their own standards: California requires shade above 80 degrees Fahrenheit for outdoor workplaces and high-heat procedures at 95 degrees for industries listed in the standard, including construction and landscaping. Maryland's standard applies at a heat index of 80 degrees, with rest breaks at 90.
Heat is the workplace hazard that field-service crews live inside for months at a time, and the regulatory picture is split. There is no final federal standard yet: OSHA published a proposed rule in August 2024, held a public hearing in the summer of 2025, and the rulemaking is still open. California and Maryland did not wait. California Title 8 Section 3395 has required shade, water and rest breaks for outdoor workers for years, with a temperature trigger at 80 degrees Fahrenheit and high-heat procedures at 95 for the industries listed in the standard. Maryland’s COMAR 09.12.32 took effect on September 30, 2024, with its own heat index triggers and mandatory rest schedules. This page covers those three regimes and no others, because those are the three whose thresholds were read from a regulator’s page today.
Who is telling you this, and why: Fieldwynn is a field-service app for small service crews, we are building it, and it has not launched. The next step at the foot of this page is an early-access email ask, not a purchase. Read the page as a funnel rather than a disinterested verdict. Every temperature, date and threshold below is quoted from a regulator’s page and linked back to it, which is the part that holds whoever runs your crews.
Three rules at a glance
| Rule | Status | Trigger threshold | Key requirement |
|---|---|---|---|
| OSHA proposed rule (federal) | Proposed (NPRM August 30, 2024). No final rule. | Not yet final; the rulemaking page does not print trigger temperatures. | Would require employers to create a plan to evaluate and control heat hazards. |
| California Title 8 Section 3395 | In effect. | 80 degrees F (shade, all outdoor workplaces), 95 degrees F (high-heat procedures, (a)(2) industries only). | Shade, water (one quart per hour per employee), rest breaks, acclimatization, written plan. |
| Maryland COMAR 09.12.32 | In effect since September 30, 2024. | 80 degrees F heat index (standard), 90 degrees F (high heat). | Written plan, shade for rest periods, rest breaks on a schedule, water (32 ounces per hour), acclimatization, training. |
The table shows the split. A construction or landscaping crew in California already operates under enforceable heat rules with specific temperature thresholds, including the 95-degree high-heat procedures that apply to their industry. A pest-control crew in Maryland operates under that state’s heat index triggers and mandatory rest schedules. A service company in a state without its own standard does not operate under a heat-specific standard with defined temperature triggers. Whether the proposed federal rule becomes final, and on what timeline, is what every service business with outdoor crews should be tracking.
The federal OSHA rulemaking: where it stands today
OSHA’s Heat Injury and Illness Prevention in Outdoor and Indoor Work Settings proposed rule was published in the Federal Register on August 30, 2024. That Notice of Proposed Rulemaking, or NPRM, was described by OSHA as “a significant step toward a federal heat standard to protect workers.”
The rulemaking has moved through four milestones so far:
- NPRM publication: August 30, 2024. The proposed standard would apply to all employers conducting outdoor and indoor work in all general industry, construction, maritime, and agriculture sectors where OSHA has jurisdiction. The standard would require employers to create a plan to evaluate and control heat hazards in their workplace.
- Public comment period: closed January 14, 2025. The public comment period for the NPRM closed on January 14, 2025.
- Informal public hearing: June 16 through July 2, 2025. The informal public hearing on the proposed rule was held June 16 through July 2, 2025, with twelve days of testimony and official transcripts available on regulations.gov.
- Post-hearing comment period: ended October 30, 2025. The post-hearing comment period for individuals who submitted a Notice of Intention to Appear (NOITA) ended on October 30, 2025.
As of 25 October 2026, no final rule has been published. The OSHA rulemaking page does not print a timeline for a final rule, and this page does not speculate on one. The specific temperature triggers and requirements in the proposed rule are published in the NPRM text at regulations.gov, not on the rulemaking summary page that was fetched today, so they are not quoted here.
For a service business planning its crew safety program, the practical takeaway is that a federal heat standard is in the rulemaking pipeline but not yet enforceable. Any state with an OSHA-approved state plan may enforce its own heat standard.
California Title 8 Section 3395: shade at 80, high-heat at 95
California’s heat illness prevention standard applies to all outdoor workplaces. The general provisions, including shade and water, cover every outdoor employer. The additional high-heat procedures in subsection (e) apply to a narrower set of industries. The standard’s (a)(1) exception states that if an industry is not listed in subsection (a)(2), employers in that industry are not required to comply with subsection (e). The industries listed in (a)(2) are: agriculture, construction, landscaping, oil and gas extraction, and transportation or delivery of agricultural products, construction materials, or other heavy materials.
The standard builds in layers around two temperature thresholds:
At 80 degrees Fahrenheit (all outdoor workplaces): Shade shall be present when the temperature exceeds 80 degrees Fahrenheit. Below 80 degrees, the employer must still provide timely access to shade when an employee requests it. Employees may take preventative cool-down rests in the shade at any time; they must be monitored and not ordered back to work until symptoms have abated, and for at least five minutes beyond the time needed to reach the shade.
At 95 degrees Fahrenheit ((a)(2) industries only): The employer shall implement high-heat procedures when the temperature equals or exceeds 95 degrees Fahrenheit. The required measures include reliable communication with supervisors, observation of employees for signs of heat illness, designated employees authorized to call emergency services, reminders to drink water, and pre-shift meetings covering the day’s heat procedures. In agriculture, when the temperature equals or exceeds 95 degrees Fahrenheit, the employer shall provide a minimum ten-minute net preventative cool-down rest period every two hours. Industries not listed in (a)(2), such as pool service or pest control, are not required to comply with subsection (e).
Water: The standard requires fresh, pure, suitably cool water provided to employees free of charge, located as close as practicable to the areas where employees are working. Where a continual supply is not plausible, the employer must provide enough at the start of the shift for each employee to drink one quart per hour for the entire shift.
Acclimatization: The standard treats new and returning workers differently. An employee who has been newly assigned to a high heat area shall be closely observed by a supervisor or designee for the first 14 days of the employee’s employment. A heat wave, defined as a day with a predicted high of at least 80 degrees that is at least 10 degrees above the average high of the preceding five days, triggers close observation of all employees.
Written plan: A written Heat Illness Prevention Plan is required, in English and the language understood by the majority of employees, covering water, shade, high-heat procedures, emergency response and acclimatization.
Training: Section 3395(h) requires that effective training shall be provided to each supervisory and non-supervisory employee before work that may expose them to heat illness risk. The job site safety inspection checklist is one place to document the shade, water and communication checks that the standard requires at the start of each day.
Maryland COMAR 09.12.32: heat index at 80, rest breaks at 90 and 100
Maryland’s heat stress standard is newer. The standard took effect September 30, 2024, and it covers indoor and outdoor workplaces where employees are exposed to a heat index of 80 degrees Fahrenheit or higher.
Where California uses air temperature, Maryland uses heat index, which factors in humidity. The distinction matters in a state with humid summers.
At a heat index of 80 degrees Fahrenheit: The standard takes effect. Employers must monitor the heat index, provide cool drinking water at no cost, close to the work area, at least 32 ounces per hour available per employee, and have a written heat-related illness prevention and management plan available to employees and MOSH on request.
Shade: Shaded areas are to be provided for employee rest periods. If a shaded area is demonstrably infeasible or unsafe, alternative cooling and control methods must be implemented.
At a heat index of 90 degrees Fahrenheit: Employers implement high heat procedures: rest periods or alternative cooling and control measures, plus mandatory employee monitoring. The rest schedule is specific:
- Heat index above 90 and below 100 degrees: at least 10 minutes of rest every 2 hours.
- Heat index above 100 degrees: at least 15 minutes of rest every hour.
Maryland’s standard also allows employers to follow NIOSH recommendations as an alternative to the mandatory rest schedule. The MOSH page states that rest periods should follow the table below or NIOSH recommendations.
Acclimatization: Employees newly exposed to heat, or returning after 7 or more days away, get up to 14 days of acclimatization, with close monitoring and the schedule in writing.
Training and records: Training must be understandable to employees, delivered before initial exposure, repeated annually, and repeated after any worksite incident involving a suspected or confirmed heat-related illness. Training records shall be maintained for one year and provided to MOSH upon request.
Other states
Several states operate OSHA-approved state plans and may enforce their own heat illness standards. This page covers only California and Maryland because those were the two state standards fetched and confirmed from regulator pages on 25 October 2026. Other states’ regulator pages were not fetched for this guide, so their specific requirements are not quoted here. If your crews work in a state not covered on this page, confirm the rules with that state’s occupational safety and health program or the relevant labor department.
What these rules mean for crew scheduling
The practical impact of these rules on a service business is in crew scheduling and route planning. A construction or landscaping crew in California that works on a 95-degree day must have shade, water and the high-heat procedures from subsection (e) running for that job. Both California and Maryland require training before an employee’s first heat exposure: California’s Section 3395(h) requires effective training before work that may expose them to heat illness risk, and Maryland requires that training must be understandable to employees and delivered before initial exposure. The labor burden rate calculator is where the cost of those rest breaks, the water supply and the training hours land in the per-hour number you charge. The guide on how to hire your first technician covers the broader onboarding sequence for a first hire, including the background checks, ride-alongs and week-one structure that frame any regulatory training you add on top.
When you are ready to carry the crew-safety documentation, the route scheduling and the training records alongside the rest of your field operations, Fieldwynn is the field-service app we are building for that load: focused in the field, powerful in the back office. It has not launched, so the next step below is an early-access email ask, and the regulatory summaries stay free either way.