Interim Guidance for Limiting Heat Burden in Ebola PPE

Monitor environmental conditions throughout work shifts and adjust work/rest schedules as needed.

• As environmental temperatures and humidity increase, personnel may need more rest breaks and additional water or electrolyte replacement.

Acclimatization is the body's gradual adjustment to working in hot environments.

Personnel who are not acclimatized are at increased risk for heat-related illnesses. Site coordinators should develop and implement work schedules that allow both new and experienced personnel to adjust gradually to hot working conditions.

Gradually increase time spent working in hot conditions (including wearing PPE) over a 7- to 14-day period.

• Schedule personnel who are new to the hot environment for no more than 20% of the usual work duration on Day 1. Increase exposure by no more than 20% of the usual work duration on each subsequent work day.
• Schedule personnel with previous experience working in similar conditions for no more than 50% of the usual work duration on Day 1, 60% on Day 2, 80% on Day 3, and 100% on Day 4.
• The tables below provide examples of implementing these acclimatization schedules during an 8-hour work shift. They are based on 30-45-minute periods while wearing fully-encapsulating PPE (called "entries") separated by rest breaks. Personnel should advance to the next acclimatization level on a subsequent day only after they have recovered adequately. Depending on the individual's ability to recover during rest breaks, additional acclimation may be needed.

Table 1. Example of acclimatization schedule for new personnel wearing fully-encapsulating PPE

*A single entry into the hot work environment while wearing fully-encapsulating PPE that lasts 30-45 minutes

Table 2. Example of acclimatization schedule for personnel with previous experience working in a hot environment while wearing fully-encapsulating PPE

*A single entry into the hot work environment while wearing fully-encapsulating PPE that lasts 30-45 minutes

PPE, environmental conditions, acclimatization levels, and work tasks should guide the work/rest schedule. Rest break times should not include the time needed to put on (don) and remove (doff) PPE.

Fully encapsulating PPE completely covers the entire body. It should not be worn continuously without a planned work/rest schedule that allows time to remove PPE, cool down, and rehydrate away from the patient care area.

Environmental conditions, including air conditioning, are only one factor affecting heat stress. Impermeable PPE can trap heat and moisture close to the skin, reducing the body's ability to cool itself through sweat evaporation. As a result, healthcare personnel can experience increasing heat strain even when temperatures and humidity are not extreme.

Site coordinators should consider multiple factors that influence heat strain when establishing work/rest schedules:

• Acclimatization status
• Environmental conditions
• Heat-related illness symptoms
• Hydration
• Individual tolerance
• Physical demands of work
• PPE ensemble

The following table provides suggested work/rest schedules based on NIOSH laboratory studies123. During the 2014–2015 Ebola Response, NIOSH evaluated heat burden associated with PPE ensembles.

Table 3. Suggested work/rest schedule for healthcare personnel in hot and humid countries affected by Ebola disease

* Fully encapsulating PPE means the entire body is covered by PPE, including the head, hands, and feet.

^† Active cooling includes wearable personal cooling systems, cooling vests, or other PPE-compatible cooling devices.

^‡ Personal cooling devices can reduce heat stress and may allow longer work periods. Consider 45–60-minute work periods only when cooling strategies and close monitoring of personnel are in place.

Site coordinators should establish and maintain rest areas that include:

• Shaded areas with chairs and cots
• Fans, misters, or other cooling devices, if available
• Bottled water and electrolyte replacement fluids or oral rehydration salts
• Basic first aid supplies
• Non-contact infrared thermometers (to check temperatures of personnel during breaks)
• Rapid cooling supplies for personnel with suspected heat-related illness, such as cool water for immersion or dousing
• Emergency communication equipment

Rest areas should have a trained monitor who can recognize symptoms of heat-related illness and provide basic first aid and cooling measures.

Monitor responsibilities can include:

• Conducting a brief mental health status assessment as personnel enter and leave the rest area.
  • Ask simple questions, such as the worker's name and the date.
  • Watch for symptoms of heat-related illness, such as slurred speech.
• Checking temperatures with an infrared thermometer at the beginning of each break.
• Ensuring personnel with normal mental status but elevated body temperature should not return to work until after they have cooled down, rehydrated, any symptoms have resolved, and their temperature has decreased to 99.5°F (37.5°C) or below.
  • Persistent or unexplained elevated temperature, especially with any other symptoms, might also indicate Ebola disease or another infectious illness, and should be handled according to facility illness-reporting and return-to-work procedures.
• Communicating when it is time for rest breaks using radios, visual signals, or messages relayed by personnel.
• Ensuring rest areas remain stocked with water, electrolyte replacement fluids or oral rehydration salts, and cooling supplies.
• Following all local emergency procedures if personnel require evacuation for medical treatment.

Heat-related illnesses can range from mild conditions such as heat rash and heat cramps to severe and life-threatening illness. Heat stroke is the most severe form and requires immediate medical treatment.

• Ensure personnel know the symptoms of heat related illness.
• Do not allow personnel with recent vomiting or diarrhea to begin a work shift, as these conditions can cause dehydration and increase the risk of heat-related illness. During an Ebola response, vomiting or diarrhea might indicate Ebola disease or another infectious illness, and should be reported and evaluated according to facility procedures.
• Require personnel to follow facility procedures for reporting illness and returning to work.

• Encourage personnel to hydrate adequately before, during, and after shifts.
• Encourage use of electrolyte replacement fluids during heavy sweating.
• Provide a space for personnel to monitor fluid loss, including a scale and a way to track weight changes.

Designate a buddy for each worker during every shift. This buddy may also serve as the IPC/PPE buddy responsible for monitoring PPE use and identifying potential breaches. Buddies should:

• Watch for symptoms of heat-related illness
• Regularly ask their buddy how he or she is feeling
• Encourage rest and water breaks
• Escort a coworker with symptoms of heat-related illness out of hot areas immediately
• Follow emergency procedures if symptoms occur or a coworker faints

Develop a plan for responding to heat-related illness. This should include procedures for situations in which a healthcare worker becomes ill or loses consciousness while wearing PPE. Specifically, the plan should cover:

• Emergency PPE removal
• Medical evaluation and treatment
• Communication
• Transportation for medical care

Before personnel enter contaminated care areas or perform duties while wearing PPE, facilities should ensure that:

• Emergency PPE removal procedures have been practiced as a team,
• Workers understand their roles and responsibilities, and
• Equipment and supplies needed for emergency PPE removal are readily available.

• Gradually increase time spent working in hot conditions over a 7-14-day period.
• If new to the hot working environment, begin with shorter shifts until your body adjusts to the heat.

• Arrive for your shift already well-hydrated.
• Drink fluids regularly and do not wait until you feel thirsty.
• Rehydrate during every rest break by drinking water, electrolyte replacement fluids, or oral rehydration salts.
• Avoid caffeine, alcohol, and other stimulants.

Monitor and record changes in your body weight to track fluid loss. Weigh yourself before putting on PPE and again after removing PPE and sweat-soaked scrubs.

Notify a supervisor if body weight decreases by 2% or more during a work shift. A loss of 2% of body weight can reduce heat tolerance and increase heart rate and body temperature. For example, a 150-lb worker who loses 3 lbs has lost 2% of their body weight (150 lbs × 0.02 = 3 lbs).

Do not begin a work shift if you have recently experienced vomiting or diarrhea. These conditions can cause dehydration, increase the risk of heat-related illness, and might indicate Ebola disease or another infectious illness. Notify your supervisor and follow the medical evaluation and return-to-work policy.

Avoid working alone. Site coordinators should assign buddies for each shift, and buddies should check in regularly with each other.

• Change out of sweat-soaked clothing during breaks
• Arrive for shifts well-rested after adequate sleep

Long work shifts

Long work shifts can increase heat stress by reducing opportunities for rest, cooling, and rehydration. Although shorter shifts are preferred, PPE supply limitations, staffing shortages, and workload demands could make them difficult to implement.

Limited electrical power

Air conditioning and fans may not be available during breaks. Limited electrical power could also restrict the use of PPE-compatible cooling systems that require refrigeration.

Limited access to electrolyte replacement fluids

Most healthcare personnel have access only to bottled water, but electrolyte replacement fluids are also important during heavy sweating.

Other illnesses

Healthcare personnel might become ill after consuming contaminated food or water. Illnesses that cause vomiting or diarrhea can lead to dehydration and increase the risk of developing a heat-related illness.

Limited medical oversight during rest periods

Sometimes, an individual who is not a healthcare provider is designated to monitor rest breaks and supplies. Limited medical oversight could delay recognition and management of heat-related illness and reduce opportunities to monitor recovery and hydration during rest breaks.

Staffing shortages

Staffing shortages may require new personnel to begin working in hot conditions before they are fully acclimatized, increasing their risk of heat-related illness. Heat-related illnesses occur more often during the first several days of work in hot conditions.

Heat-related illnesses can range from mild conditions to life-threatening emergencies. Review the risk factors for heat-related illness.

Early symptoms of heat stroke can include changes in cognitive function including:

• Confusion
• Slurred speech
• Difficulty performing routine tasks

These symptoms can interfere with the proper removal (doffing) of PPE and can increase the risk of exposure to blood or body fluids while doffing.

Heat stress associated with impermeable PPE can also cause:

• Dehydration
• Cardiovascular strain
• Heat syncope (fainting)

These effects can be exacerbated by fluid losses from illnesses that cause vomiting or diarrhea. If a healthcare worker loses consciousness while caring for a patient, the resulting fall or loss of control may damage PPE or dislodge respiratory protection, potentially increasing the risk of exposures to infectious materials.

Prescreening healthcare personnel for medical conditions, medication use, history of heat illness, and other risk factors can reduce the risk of heat-related illness while working in hot environments.

A designated individual should periodically monitor environmental conditions using a wet-bulb globe temperature (WBGT) device or local weather information when available.

Environmental conditions are only one factor affecting heat stress. Impermeable PPE can trap heat and moisture close to the skin, reducing the body's ability to cool itself through sweat evaporation. As a result, healthcare personnel may experience increasing heat strain even when temperatures and humidity are not extreme.