Heat Discomfort Zones

Maximum work load vs. temperature and relative humidity.

Temperature (°F)	Temperature (°C)	Relative Humidity 30%	Relative Humidity 40%	Relative Humidity 60%	Relative Humidity 80%
80	27	Very Heavy	Very Heavy	Very Heavy	Heavy
90	32	Very Heavy	Heavy	Moderate	Light
100	38	Heavy	Moderate	Light	Not recommended
110	43	Moderate	Light	Not recommended	Not recommended
120	49	Light	Not recommended	Not recommended	Not recommended