Indoor/outdoor relationship of fine particles less than 2.5 μm (PM2.5) in residential homes locations in central Indian region

The high levels in developing countries and the apparent scale of its impact on the global burden of disease underline the importance of particulate as an environmental health risk and the consequence need for monitoring them particularly in indoor microenvironment. PM2.5 μm, 1.0 μm, 0.5 μm and 0.25 μm were measured inside and outside 14 residential homes located in different microenvironment during a six-month period (October 2007–March 2008) in Agra located in the central region of India. Particulate mass concentrations were measured using Grimm aerosol spectrometer for 24 h inside and outside the homes located in roadside, rural and urban area, along with the field survey study done in the same region. The indoor average concentrations recorded for PM2.5, PM1.0, PM0.5 and PM0.25 were maximum for the rural homes (173.03 μgm−3, 133.26 μgm−3, 96.02 μgm−3, 8.56 μgm−3) followed by roadside homes (137.93 μgm−3, 117.09 μgm−3, 68.17 μgm−3, 8.55 μgm−3) and then by urban homes (135.55 μgm−3, 102.92 μgm−3, 38.38 μgm−3, 6.35 μgm−3). The average I/O ratios for PM2.5, PM1.0, PM0.5 and PM0.25 in roadside and rural areas were close to or above 1.00 and less than 1.00 for urban areas. The I/O ratios obtained were linked to the indoor activities using occupant's diary entries. The positive values of correlation coefficient (r) also indicated the indoor concentrations of particulate matter were correlated with the corresponding outdoor concentrations.