▁Resource ▁Centre . ▁▁ ▁The ▁centre ▁took ▁eleven ▁air ▁samples ▁in ▁and ▁around ▁North ▁Chen na i ▁and ▁Chen na i ▁city ▁as ▁part ▁of ▁their ▁air ▁quality ▁study ▁in ▁En n ore ▁ 2 0 1 6 . ▁▁ 2 4 - hour ▁samples ▁were ▁taken ▁using ▁filters ▁fitted ▁to ▁a ▁low ▁volume ▁air ▁sam pler ▁and ▁anal ys ed ▁for ▁PM ▁ 2 . 5 ▁( Part ic ulate ▁M atter ▁or ▁dust ▁less ▁than ▁ 2 . 5 ▁mic rom eters ▁in ▁size ). ▁The ▁key ▁documented ▁sources ▁of ▁PM ▁ 2 . 5 ▁poll ution ▁are ▁autom obile ▁exhaust , ▁burning ▁of ▁coal , ▁burning ▁garbage ▁and ▁land fill , ▁sm el ting ▁processing ▁of ▁met als . ▁ ▁Sur pr ising ly , ▁ 1 0 ▁out ▁of ▁the ▁ 1 1 ▁air ▁samples ▁were ▁between ▁ 1 . 4 ▁and ▁ 3 . 7 ▁times ▁higher ▁than ▁pres cribed ▁by ▁the ▁Ministry ▁of ▁Environment , ▁For ests ▁and ▁Cl imate ▁Change . ▁The ▁air ▁quality ▁of ▁N all ath ane er ▁O da i ▁K upp am ▁in ▁En n ore ▁is ▁the ▁highest ▁with ▁ 2 2 0 ▁micro gram s ▁per ▁cub ic ▁meter ▁air . ▁ ▁Other ▁areas ▁from ▁En n ore ▁include ▁Man ali ▁with ▁ 1 5 6 ▁u g / m 3 , ▁S ivan p ada ive eth i ▁K upp am ▁with ▁ 1 5 6 . ▁ 9 0 ▁u g / m 3 ▁and ▁K oding ay