Lead concentration in the air Settings N Mean ± SD (µg / m3) Min Max Over of VN standard (n /%) Ban Thi (1) 30 5, 89 ± 4, 19 1, 6 18, 5 30 (100, 0) Tan Long (2) 30 6, 79 ± 5, 37 2 30, 2 30 (100, 0) p1&2 (Mann Whitney test) 0, 277 Interpret: The lead concentrations in the air in Ban Thi and Tan Long were 4 - 4.5 times more likely than the VN standards Table 3.18.