Table 1. The lowest temperature in 2011 and 2012.

Medium	Place	n	Temperature (°C) (mean±SD)5)
Air	Outside1)	2	8.5±0.7 a
	Room2)	4	13.4±1.0 b
Water	Metal tank3)	2	11.3±1.2 ab
	Concrete tank4)	14	18.2±1.9 c

¹⁾National Hydro-Meteorological Service (2012).

²⁾Room temperature in public health centers of Hoang Mai and Ha Dong districts.

³⁾Metal tank set in Hoan Kiem district.

⁴⁾Concrete tanks set in seven districts (Dong Da, Hai Ba Trung, Hoang Mai, Thanh Xuan, Thanh Tri, Tu Liem, and Ha Dong).

⁵⁾Different letters following means in a row indicate significant difference at p<0.05 by Tukey’s test.