Monitoring
When you're working in the heat, safety comes first. Because the incidence of heat stress depends on a variety of factors, all workers, even those not wearing protective equipment, should be monitored.
- For workers wearing permeable clothing (e.g., standard cotton or synthetic work clothes), follow recommendations for monitoring requirements and suggested work/rest schedules in the current American Conference of Governmental Industrial Hygienists' (ACGIH) Threshold Limit Values for Heat Stress.
- For workers wearing semi-permeable or impermeable encapsulating ensembles, the ACGIH standard cannot be used. For these situations, workers should be monitored when the temperature in the work area is above 70°F (21°C).
Initially, the frequency of physiological monitoring depends on the air temperature adjusted for solar radiation and the level of physical work.
The length of the work cycle will be governed by the frequency of the required physiological monitoring. Review the suggested frequency of physiological monitorng for PPE fit in the link below.
| Adjusted Temperature (see notes below) | For workers with normal work clothes, conduct monitoring... | For workers wearing impermeable protective clothing conduct monitoring... |
|---|---|---|
| 90°F or above | After each 45 minutes of work | After each 15 minutes of work |
| 87.5°-90°F | After each 60 minutes of work | After each 30 minutes of work |
| 82.5°-87.5°F | After each 90 minutes of work | After each 60 minutes of work |
| 77.5°-82.5°F | After each 120 minutes of work | After each 90 minutes of work |
| 72.5°-77.5°F | After each 150 minutes of work | After each 120 minutes of work |
Notes:
a Assumes work levels of 250 kilocalories/hour (e.g., a moderate work level). Consider increasing the frequency for heavy work rates.
b Adjusted Air Temperature: Calculate the adjusted air temperature (ta adj) by using this equation: ta adj °F = ta °F + (13 x % sunshine). Measure the air temperature (ta) with a standard thermometer, with the bulb shielded from radiant heat. Estimate the percent sunshine by judging what percent time the sun is not covered by clouds that are thick enough to produce a shadow. 100 percent sunshine = no cloud cover and a sharp, distinct shadow; >0 percent sunshine = no shadows
c For the purpose of this chart, a normal work ensemble consists of cotton coveralls or other cotton clothing with long sleeves and pants.
To monitor the worker, measure:
- Heart Rate Count the radial pulse during a 30-second period as early as possible in the rest period.
- If the heart rate exceeds 110 beats per minute at the beginning of the rest period, shorten the next work cycle by one-third and keep the rest period the same.
- If the heart rate still exceeds 110 beats per minute at the next rest period, shorten the following work cycle by one-third.
- Oral Temperature Use a clinical thermometer (3 minutes under the tongue) or similar device to measure the oral temperature at the end of the work period (before drinking).
- If oral temperature exceeds 99.6°F (37.6°C), shorten the next work cycle by one-third without changing the rest period.
- If oral temperature still exceeds 99.6°F (37.6°C) at the beginning of the next rest period, shorten the following work cycle by one-third.
- Do not permit a worker to wear a semi-permeable or impermeable garment when his/her oral temperature exceeds 100.6°F (38.1°C).
Measure weight on a scale accurate to ±0.25 lb. at the beginning and end of each work day to see if enough fluids are being taken to prevent dehydration. Weights should be taken while the employee wears similar clothing or, ideally, is nude. The body water loss should not exceed 1.5 percent total body weight loss in a work day.
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Knowledge Check Choose the best answer for the question.
6-3. If an employee is wearing impermeable protective clothing and the temperature is 88 degrees, how often should you monitor the employee?
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