Citation:
Nasir ZA, Colbeck I, Ali Z and Ahmed S. Heavy metal composition of particulate matter in rural and urban residential built environments in Pakistan. The Journal of Animal and Plant Sciences, Volume 25, Issue 3, 2015, pp. 706-712
Abstract:
Heavy metals in outdoor and indoor airborne particulate matter (PM) and dust in different residential built
environmentsat two rural and one urban site in Pakistan were analysed. An eight stage non-viable impactor (Thermo
Fisher Scientific Inc., USA) loaded with EMP 2000 glass microfiber filter papers (Whatman, England) was used to
collect airborne PM.The indoordust samples (settled dust) were collected from different indoor surfaces (floor,
cupboards) in living rooms and kitchens from houses at rural sites. The outdoor samples were collected from courtyards
of the houses.At the urban site dust samples were also collected by the roads at 27 different locations around Lahoreand
at a background site (University of Veterinary and Animal Sciences).Additionally, samples of dung cake, used as solid
fuel, at one of the rural sites were taken.Heavy metals (Si, Al, Zn, Mn, Cu, Ni, Cd, Pb, Co and As) were determined by
Graphite Furnace Atomic Absorption Spectrophotometer. At rural site I, in general, the concentrations of metals were
higher outdoors than indoors, except for slightly higher indoor levels of Cu (0.85.g/m3 indoor: 0.56 outdoor.g/m3 ), Si
(3.31.g/m3 indoor: 3.17 outdoor.g/m3 ) and Pb(11.99 ng/m3 indoor: 9.32 outdoor ng/m3 ). At the rural site II the mean
concentration were higher outdoors than indoors, excluding Ni which was considerably higher indoors (55.68 ng/m3 )
than outdoors (31.91 ng/m3 ).At the urban site,outdoors, Si had the highest concentration (3.46 .g/m3 ) followed by Al,
Zn, Mn, Cu, Ni, Cd, Pb and Co. Similarly, the indoor levels had a maximum contribution from Si (12.30 .g/m3 )
followed by Al, Mn, Zn, Cu, Cd, As, Pb, Ni and Co.With reference to dust at rural site I the top five metals outdoors
were Si (708 mg/kg), Al, Cu, Zn and Pb (52 mg/kg) while, indoors Al was highest (281 mg/kg), followed by Si, Cu, Zn
and Pb (57 mg/kg). At rural site II, both outdoors and indoors, Al (274 mg/kg – outdoor: 266 mg/kg - indoor), Si, Zn, Cu
and Pb (61 mg/kg – outdoor: 80 mg/kg - indoor) were the five most abundant metals.The main five metals in decreasing
order of their concentration in the road dust around Lahore were Si (686 mg/kg), Al, Cu, Zn and Pb (81 mg/kg). On the
other hand, the dust samples from the background site showed Si (345 mg/kg) > Al >Pb> Cu > Zn (73 mg/kg). The
airborne metal concentration of Pb was within the guideline value of WHO (0.5 .g/m3 ) but the levels of Mn, Cd and Ni
were higher at all sites than the guidelines proposed by European Commission and WHO highlighting the risk of
exposure to toxic metals in non-occupational environments.