Heat stress is the overall effect of excessive heat on the human body. Prolonged exposure to high air temperatures or to high humidity at even more moderate temperatures may cause the body temperatures of people of all ages to rise and produce one or more of the signs of heat stress affecting the ability to learn, work, or even play.
Those at highest risk are the very young, the elderly, people with acute or chronic health problems, and people using certain medication or taking illicit drugs. For various reasons, not all people tolerate heat to the same extent.
To counteract heat stress, all District personnel must pay attention to these contributing factors:
- air temperature
- air circulation
- radiant heat
- air pollution
- classroom temperature
- classroom location
- medical problems and use of medications
- fluid intake
- appropriate clothing
- physical conditioning
- acclimation to heat
- intensity, type and duration of exercise
Common sense and good judgment must always be applied by staff when analyzing site conditions.
Please note: Students with certain health problems may require more attention. If students complain about the heat, allow them to rest or see the school nurse who may want to have their health status clarified by a parent or guardian.
Employees with specific health problems should make them known to site administrators.
2. Weather Conditions For Modifying Activities Or School Day
Authorities in the fields of medicine, environmental and occupational hazards, and safety have thoroughly studied heat stress and have issued guidelines pertaining to modifying physical activity and school or work schedules. It is recommended that temperature and humidity readings be obtained from the National Weather Bureau. Local news reports on radio and television also carry this information.
The following chart provides guidelines for consideration in modifying instructional programs, physical activity, and school schedules:
|Possible Heat Stress Effects|
Humidity less Humidity 50%
than 50% or greater
|· Good learning conditions. No effect.||· Regular school day||· Regular school day.|
· Learning may decrease with long exposure.
· Fatigue may increase after 4-6 hours.
· Regular school day.
· If near 50% humidity, limit intensity of or modify physical activity and monitoring.
· Regular school day.
· Limit duration & intensity of or modify physical activity & monitor closely.
|· Early heat|
· Heat exhaustion or heat stroke possible
with long exposure.
· Regular school day.
· Limit duration & intensity of or modify physical activity & monitor-closely.
· Regular school day
· Limit duration & intensity of & modify physical activity & monitor closely.
|Extreme Caution||95° or above**||· Heat stroke or heat exhaustion possible.|
· Consider schedule change.
· Prohibit or limit duration & intensity of, modify physical activity, & monitor closely.
· Consider schedule change.
· Prohibit physical activity.
* Air pollution alerts MUST be obeyed in all categories.
**If air circulation (or wind velocity) is 10 mph or greater, the effects of temperature may be less severe.
3. Procedures For Conducting Classroom Activities
On very hot, humid days, administrators, teachers, and other staff should be aware of the following procedures to help minimize possible heat stress.
- Faculty and staff must be informed at the beginning of each semester, and as needed thereafter, about the school’s program for preventing heat stress and the most efficient methods for reducing heat and maximizing ventilation in classrooms.
- Doors and windows must be closed in air-conditioned rooms, and any air-conditioning equipment malfunction should be reported at once.
- When possible, all air-conditioned rooms should be used as classrooms.
- Non-air conditioned classrooms should be surveyed by teacher or principal’s designee when temperatures require that maximum cooling efforts be instituted, including:
- Windows, doors, transoms, and shades/blinds should be adjusted for maximum ventilation and air circulation.
- Electric fans, where available, should be placed to bring in fresh air and exhaust stale air rather than just blowing it around the room. Fans should be turned on as early as possible including the night before based on the weather forecast. Adjusting custodial hours should be considered to permit early entry into classrooms to open doors, windows, transoms, and turn on fans.
- Precautions should be taken to ensure that when fans, coolers, or other devices are used they meet safety standards and that cooling strategies do not place an overload on existing electrical systems.
- When classroom temperatures exceed 92°, consideration should be given to moving students to cooler rooms or other appropriate areas, such as the auditorium, multipurpose room, library, or shaded outdoor areas. Where possible, classes should be combined in air-conditioned rooms.
- Teachers, especially at the elementary level, may adjust their programs to use the cooler early hours for physical activity.
- Water must be available. Personal water containers are recommended for use when heat is excessive as a means to prevent dehydration. Use at other times should be a local school option.
The following are recommended precautions:
- For health reasons, water containers should not be shared.
- For safety reasons, students should not run with straws or containers in mouth.
- For safety reasons, containers may not be used while riding District buses.
- Students should not bring containers to physical education activity areas unless given permission by the physical education teacher. Staff and all personnel supervising physical activities, should observe students during activity periods and modify activities as recommended in Section II. Students known to have health problems should be closely observed and their activity modified or restricted.
- Precautions For Outdoor Activities
During times of excessive heat, the following precautions need to be taken for outdoor physical activity, which includes recess, physical education, recreation, and competitive sports:
- The intensity of exercise activities must be limited or they must be modified whenever air temperature and humidity are above caution levels (refer to Section II).
- Adequate water must be available. If adequate water is not available, physical activity must be modified. Prior to prolonged physical activity, a person should be fully hydrated. During the activity, periodic drinking of water every 15 to 30 minutes should be encouraged. Use of salt tablets is not advised, and commercially available replacement fluids for athletes are not usually necessary. Sugary and alcoholic beverages cause dehydration. Carbonated beverages may cause abdominal pain.
If water fountains are not located near the place of activity, large urns from the cafeteria may be filled with water and placed in strategic locations.
- Proper clothing should reflect heat, permit freedom of movement, and allow free perspiration. Clothing should be light colored, lightweight, loose, and limited to one layer of absorbent material in order to facilitate evaporation of sweat and expose as much skin as possible, yet still be appropriate for the school environment.
Sweat-saturated garments should be replaced by dry ones. Rubberized sweat suits should never be used to produce loss of weight. Sunscreen, proper clothing, and hats should be used to prevent sunburn.
- Staff and all personnel supervising physical activities should observe students during activity periods and modify activities as recommended in Section II. Students known to have health problems should be closely observed and their activity modified or restricted.
- Teachers must observe students closely and know signs and symptoms of heat stress, emergency first aid, and how to obtain medical help.
- Marked differences between indoor and outdoor temperatures may precipitate physical problems.
- Secondary and adapted physical education teachers should modify the type, duration, and intensity of exercise.
- Rest periods should be provided during activity.
- Activities must be followed by the proper cool-down (for example, jogging should be followed by walking) and rest.
- Athletes engaging in competitive sports must have their activities closely observed for all of the above considerations.
- Other strenuous student activities–such as drill team, marching band, cheerleading, and the like–must be closely observed by teachers, coaches, and other certificated personnel assigned to supervise such activities.
- Additional Strategies For Preventing Heat Stress
- The contents of this protocol should be reviewed annually and as otherwise needed. Teachers, staff, parents, and students should be instructed by school nurses regarding awareness of signs and symptoms and first aid for problems attributable to excessive heat. Teachers should explain precautions to students.
- A “cool room” should be established for use by students showing early signs of heat stress. This room should provide maximum coolness possible. During an emergency, if an air-conditioned classroom is to be used as a “cool room” and is occupied by students, the students should be moved to another location. During excessive heat the “cool room” should be available for use at all times during the school day.
Data used in this bulletin was adapted in part from:
- American Academy of Pediatrics, Committee on School Health, “Heat Stress and School Closings,” Pediatrics, Vol. 74, No. 2, 1984
- American Academy of Pediatrics, Committee on Sports Medicine, “Climate Heat Stress and the Exercising Child and Adolescent,” Pediatrics, Vol. 10 No. 1, July 2000.
- Los Angeles Unified School District Policy Bulletin, BUL-963, April 1, 2004