Table 2.
The thermal perception and stress levels of physiological equivalent temperature(PET) and universal thermal climate index(UTCI)(Jung et al., 2016)

Thermal perception	PET(°C)	UTCI(°C)	Grade of physiological stress
Very cold	⟨ 4	⟨ −40	Extreme cold stress
		−40∼−27	Very strong cold stress
Cold	4∼8	−27∼−13	Strong cold stress
Cool	8∼13	−13∼0	Moderate cold stress
Slightly cool	13∼18	0∼9	Slight cold stress
Neutral	18∼23	9∼26	No thermal stress
Slightly warm	23∼29		Slight heat stress
Warm	29∼35	26∼32	Moderate heat stress
Hot	35∼41	32∼38	Strong heat stress
Very hot	⟩ 41	38∼46	Very strong heat stress
		⟩ 46	Extreme heat stress