Table 2. January average temperature in 2011 and 2012.

Medium	Place	n	Temperature (°C) (mean±SD)5)
Air	Outside1)	2	13.7±1.3 a
	Room2)	4	16.2±1.2 a
Water	Metal tank3)	2	17.3±1.6 ab
	Concrete tank4)	14	20.0±1.7b

¹⁾National Hydro-Meteorological Service (2012).

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

³⁾Metal tank set in Hoan Kiem.

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.