Abstract
The present study investigated the particle size distribution of trace metals (Fe, Pb, Mn, Cu, Ni, Cr, Zn, Cd, Hg, and As) in the domestic environment, and examined the relationships among the levels of these metals and identified the related sources. Five homes at each site i.e., urban, rural and roadside, were selected for sampling. PM10 and PM2.5 samples were collected by using an APM-550 particulate sampler. Metals were analyzed by AAS after acid digestion. The monthly average PM2.5 concentration ranged from 80 to 184.67 µg/m3, while the PM10 monthly concentration ranged from 167.56 to 307.95 µg/m3. PM2.5 contributed 50–56% of PM10. The total contribution of the analyzed trace metals in PM2.5 was 6.2% while in PM10 it was 2.2%. This followed the order Fe > Zn > Pb > Cr > Ni > Cu > Mn. Pb and Ni exceeded the prescribed annual National Ambient Air Quality Standards (NAAQS) given by the Central Pollution Control Board (CPCB) by up to 5 and 36 times, respectively. For Pb and Ni it is 0.50 µg/m3 and 0.02 µg/m3, respectively. The particle mass was concentrated in the coarse size fraction, and the mass of individual trace metals was concentrated in finer sizes (except Fe), which is a major issue of concern. Intercorrelations and Principal Component Analysis were used to classify the two groups of sources, one from house dust and anthropogenic activities indoors, and the other from infiltration from outdoors. Enrichment factors with respect to outdoor metal concentrations have been identified for each metal. Fe was found to be totally contributed by outdoor dust. Mn and Cr are found to be less enriched, while Pb, Ni, Zn and Cu were found to have indoor sources.
Highlights
Fine particles (PM2.5), with an aerodynamic diameter smaller than 2.5 μm, is considered to be more hazardous than larger size particulate matter (PM) due to its longer residence time in the atmosphere and can penetrate deep into the alveolus of human beings through breathing (Feng et al, 2009; Massey et al, 2009; Satsangi et al, 2011)
The trends of particulate mass concentration in PM10 and PM2.5 were road > rural > urban. This indicates that air quality in rural and roadside sites is affected by particulate matter (PM) and that urban site has relatively better air quality
The PM2.5/ PM10 ratio according to WHO standards (2005) is 0.50 and that by National Ambient Air Quality Standards (NAAQS) (2009) given by CPCB (Central Pollution Control Board, India), it is 40 μg/m3/60 μg/m3 i.e. 0.66
Summary
Fine particles (PM2.5), with an aerodynamic diameter smaller than 2.5 μm, is considered to be more hazardous than larger size PM due to its longer residence time in the atmosphere and can penetrate deep into the alveolus of human beings through breathing (Feng et al, 2009; Massey et al, 2009; Satsangi et al, 2011). One category of indoor pollutant, which is known to be toxic, is that of heavy metals Heavy metals find their way into residential homes either as airborne dust or through items used or activities carried out within the house like renovation or different cooking methods. Vulnerable in this respect are young children, who may ingest several milligrams of indoor and outdoor dusts per day through the repetitive mouthing of non-food objects (Fergusson and Marsh, 1993). The makeup of the latter is often dominated by external solids, like soils and road-dusts, and contains appreciable quantities of particulates generated internally from cooking, smoking, heating, decorating and the application of cosmetics
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