An Exploration of Temperature Metrics for Further Developing the Heat-Health Weather Warning System in Hong Kong

Table 4

Summary of threshold temperatures for various temperature metrics.

Temperature metrics	Threshold temperature (°C)	No. of days exceeded from 1999 to 2009	% increase in median mortality anomaly
𝑇max (summer)
All-cause	≥35	3	2.5
RD	Nil	Nil	Nil
CVD	≥35	3	15
𝑇min (winter)
All-cause	Nil	Nil	Nil
RD	≥21	14	6
CVD	≥21	14	2.5
Mean AT
All-cause	≤8	10	2.5
RD	Nil	Nil	Nil
CVD	≤8 (≥38)	10 (52)	4 (7)
Mean NET
All-cause	≥27	4	2
RD	≤−3	10	12
CVD	≥27	4	11
Max NET (summer)
All-cause	Nil	Nil	Nil
RD	Nil	Nil	Nil
CVD	≥30	38	4
Min NET (winter)	Nil for all-cause, RD, and CVD
DTR (all season)
All-cause	≥10	5	6
RD	≥8	33	5
CVD	≥8	33	3
DTR (summer)
All-cause	≥8	6	4.5
RD	Nil	Nil	Nil
CVD	≥8	6	16
DTR (winter)
All-cause	≥7.1	23	1.5
RD	≥8	6	15
CVD	≥8	6	2.5
Temp change (𝑇mean)
All-cause	≥4.1	11	6
RD	≥4.1	11	7
CVD	Nil	Nil	Nil
Temp change (𝑇max)
All-cause	≥5.6	7	3
RD	≥5.6	7	4
CVD	Nil	Nil	Nil
Temp change (𝑇min)	Nil for all-cause, RD and CVD