Failing to get the time to acclimate to a hot work environment can be deadly. That’s the message I took away from an item in last week’s Morbidity and Mortality Weekly Report (MMWR).

“Heat illness and deaths among workers — U.S. 2012-2013” reports on 13 occupational heat-related fatalities investigated by federal OSHA.  Nine of the 13 incidents (69 percent) involved an individual who was working in their hot job for three or fewer days. Among the cases examined by the authors, none of the employers had acclimation programs, and only five of the 13 had provided access to a cool or shaded area for rest breaks. In nearly all the cases, the deceased workers’ opportunity for a rest break came only during scheduled breaks—not necessarily at frequent enough time periods to assist with acclimation.

The MMWR report, prepared by OSHA and NIOSH staff, notes:

“New workers and all workers returning from an absence of more than a week should begin with 20 percent of the usual duration of work in the hot environment on the first day, increasing incrementally by no more than 20 percent each subsequent day.”

The report shows the diversity of jobs and situations in which workers are at risk of suffering a heat-related illness or death.  Three of the 13 fatalities involved waste collection/recycling workers, two were postal workers, and others included a roofer, a turf grass installer, and a person working in a commercial laundry.

The authors’ data, as they acknowledge, is only a subset of all work-related fatal heat-illnesses cases.  It does not include, for example, incidents from California, North Carolina and the 19 other states that operate their own OSHA program. Moreover, it only includes cases for which the employer received a citation from federal OSHA for not addressing the fatal heat hazard.  Because OSHA doesn’t have a regulation on heat stress, such citations were written as “general duty clause” violations (i.e., failing to provide a workplace that is free from recognized hazards that are likely to cause serious physical harm.) The above quote from the report is only a recommendation, not a requirement.

In 2011, Public Citizen and Farmworker Justice submitted a petition to OSHA urging the agency to issue a standard on heat stress. The petition reminded us that NIOSH recommended in 1972 a comprehensive worker safety standard on heat exposure, and repeated the call in 1986. The organizations also noted that the states of California, Minnesota and Washington have, to varying degrees, standards to address hot work environments.  (Minnesota’s regulation covers indoor environments only and Washington’s regulations cover outdoor environments only, with Washington’s applicable from May through September.)  All three standards recognize the importance of acclimation, most notably the California standard which requires:

“ Close supervision of a new employee by a supervisor or designee for the first 14 days of the employee’s employment by the employer, unless the employee indicates at the time of hire that he or she has been doing similar outdoor work for at least 10 of the past 30 days for 4 or more hours per day.”

Earlier this year, NIOSH solicited public comments on (yet again) a draft recommended standard on occupational exposure to heat and hot environments.  The “Criteria for a Recommended Standard: Occupational Exposure to Heat and Hot Environments” notes the advantages of acclimation:

• Increased sweating efficiency (earlier onset of sweating, greater sweat production, and reduced electrolyte loss in sweat)
• Work is performed with lower core temperature and heart rate
• Increased skin blood flow at a given core temperature

And offers this draft acclimization plan:

• Gradually increase exposure time in hot environmental conditions over a 7-14 day period.
• For new workers, the schedule should be no more than 20 percent exposure on day 1 and a no more than 20 percent increase on each additional day.
• For workers who have had previous experience with the job, the acclimization regime should be no more than a 50 percent exposure on day 1, 60 percent on day 2, 80 percent on day 3, and 100 percent on day 4.

As they’ve done in the last few years, federal OSHA has teamed up with the National Weather Service to raise awareness about heat-related illness.  The slogan “Water. Rest. Shade.” has become the hot-weather mantra in some worker safety circles.  The report on these 13 heat-related worker fatalities, however, makes me wonder whether the slogan needs an update. Water, shade and rest may not be enough if newly assigned workers haven’t had a chance to adjust to the heat.