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TABLE 5-1 Threshold Limit Values Work/Warm-up Schedule for Four-Hour Shift* Air-Temperature—Sunny Sky No Noticeable Wind 5 mph Wind 10 mph Wind 15 mph Wind 20 mph Wind Max.Work No.of Max.Work No.of Max.Work No.of Max.Work No.of Max.Work No.of °C(approx.) °F(approx.) Period Breaks Period Breaks Period Breaks Period Breaks Period Breaks -26'to-28° -15°to-19' (Noun.Breaks)1 (Norm.Breaks)1 75 min 2 55 min 3 40 min 4 -29°to-31' -20°to-24° (Noun Breaks)1 75 min 2 55 min 3 40 min 4 30 min 5 -32'to-34° -25°to-29' 75 rein 2 55 min 3 40 min 4 30 min 5 Non-emergency work should cease -35'to-37' -30°to-34° 55 min 3 40 min 4 30 min 5 Non-emergency Non-emergency work should cease work should cease -38°to-39° -35'to-39° 40 min 4 30 min 5 Non-emergency Non-emergency Non-emergency work should cease work should cease work should cease -40'to-42' 40'to-44° 30 min 5 Non-emergency Non-emergency Non-emergency Non-emergency, work should cease work should cease I work should cease work should cease -43'&below -45'&below Non-emergency Non-emergency Non-emergency Non-emergency Non-emergency work should cease work should cease work should cease work should cease work should cease *1, Schedule applies to any 4-hour work period with moderate to heavy work activity,with warm-up periods often. (10)Minutes in a warm location and with an extended break(e.g.,lunch)at the end of the 4-hour work period in a warm location. For Light-to-Moderate Work(limited physical movement):apply the schedule on step lower. For example,at-35°C(-30°F)with no noticeable wind(Step 4),a worker at ajob with little physical movement should have a maximum work period of 40 minutes with 4 breaks in a 4-hour period(Step 5). 2. The following is suggested as a guide for estimating wind velocity if accurate information is not available: 5 mph: light flag moves;10 mph: light flag fully extended: 15 mph: raises a newspaper sheet:20 mph: blowing and drifting snow. 3. If only the wind chill cooling rate is available,a rough rule of thumb for applying it rather than the temperature and wind velocity factors given above would be 1)special warm-up breaks should be initiated at a wind chill cooling rate of about 1750 watts per square meter(W/m2);2)all non-emergency,work should have ceased at or before a wind chill of 2250 W/mr. In general,the warm-up schedule provided above slightly under-compensates for the wind at the warmer temperatures,assuming acclimatization and clothing appropriate for winter work On the other hand,the chart slightly overcompensates for the actual temperatures in the cooler ranges because windy conditions rarely prevail at extremely low temperatures. 4. TLVs apply only for workers in dry clothing. * Adapted from Occupational Health&Safety Division,Saskatchewan Depamnent of Labor. HASP Level III Rev.(September 17,2012) 5-13