Exposure of children studying in schools of India to PM levels and metal contamination: sources and their identification

The concentration of particulate matter (PM) 10 , PM 5.0 , PM 2.5 , PM 1.0 , PM 0.50 , and PM 0.25 was measured along with heavy metals (Fe, Zn, Cu, Cd, Cr, Mn, Ni, and Pb) collected from settling dust in the indoor–outdoor environment of roadside and residentially located schools of Agra City, from January 2008 to May 2009. PM indoor/outdoor ratios at the roadside and residentially located schools were also determined by the meteorological parameters like temperature, humidity, and wind speed and air exchange rate. Metal geoaccumulation index shows that the contamination of Fe, Cd, Cr, Ni, Pb, and Mn was in abundant quantity in residential and roadside soil dust of the schools. The enrichment factor was calculated using Ca as a reference to the trace metal species to identify the sources. Three factors in inside and three outside the classrooms of roadside and residentially located schools were identified. These factors reflected source soil dust, road dust, vehicle emissions, industrial emissions, metal processes, and incineration activities and their contributions were estimated using principal component analysis. Measurements of such exposure levels would be helpful in prevention of environmental risks to schoolchildren at a global level for better and healthy mind of children studying at schools.