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Surface measurements of O 3 , NO, NO 2 and NO x have been made over a semi-arid rural site, Anantapur (14.62°N; 77.65°E; 331 m asl) in southern India, during January-December 2010. The highest monthly mean O 3 concentration was observed in April (56.1 ± 9.9 ppbv) and the lowest in August (28.5 ± 7.4), with an annual mean of 40.7 ± 8.7 ppbv for the observation period. Seasonal variations in O 3 concentrations were the highest during the summer (70.2 ± 6.9 ppbv), and lowest during the monsoon season (20.0 ± 4.7 ppbv), with an annual mean of 40.7 ± 8.7 ppbv. In contrast, higher NO x values appeared in the winter (12.8 ± 0.8 ppbv) followed by the summer season (10.9 ± 0.7 ppbv), while lower values appeared in the monsoon season (3.7 ± 0.5 ppbv). The results for O 3 , NO and NO 2 indicate that the level of oxidant concentration ([OX] = NO 2 + O 3 ) at a given location is the sum of NO x -independent "regional contribution" (background level of O 3 ) and linearly NO x -dependent "local contribution". The O 3 concentration shows a significant positive correlation with temperature, and a negative correlation with both wind speed and relative humidity. In contrast, NO x have a significant positive correlation with humidity and wind speed, and negative correlation with temperature. The slope between [BC] and [O 3 ] suggests that every 1 μg/m 3 increase in black carbon aerosol mass concentration causes a reduction of 4.7 μg/m 3 in the surface ozone concentration. A comparative study using satellite data shows that annual mean values of tropospheric ozone contributes 12% of total ozone, while near surface ozone contributes 82% of tropospheric ozone. The monthly mean variation of tropospheric ozone is similar to that tropospheric NO 2 , with a correlation coefficient of +0.80.

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This study investigated the characteristics of both filterable fine particulate matter (FPM) and condensable particulate matter (CPM) emitted from coal-fired boilers (CFBs) and oil-fired boilers (OFBs) via field sampling. FPM and CPM samples were collected using USEPA Method 201A and Method 202, respectively. Mass concentrations and chemical compositions (including water-soluble ions, metal elements and carbon contents) of collected PM2.5 samples were analyzed. The results show that PM2.5 (FPM + CPM) emission concentrations for CFBs and OFBs are 20.2 ± 10.4 and 157 ± 82.7 mg/Nm3, respectively. In terms of the emission factor, emission of FPM from OFBs is 307.4 ± 50 g/kL of oil and from CFBs is 57.1 ± 13.8 g/t of coal. Significantly higher concentrations are emitted from OFBs than from CFBs due to the reason that better control devices are installed in most CFBs. The average CPM fraction constitutes 58.7 and 54.8% of PM2.5 for CFBs and OFBs, respectively, showing that CPM from the boilers contributes a significant fraction of PM2.5 emissions. FPM sample analysis reveals that SO4 2– is the primary characteristic of water-soluble ion and occupies 64.2 and 80.6% of total water-soluble ions for CFBs and OFBs, respectively. SO4 2– is a main contributor of ions, while NO3 – follows. The species in CPM are dominated by water-soluble ions, including SO4 2–, NO3 –, and NH4 +. The results indicate that CPM is formed primarily by water-soluble ions. The results also show that organic carbon (OC) concentrations are predominant for CFBs, and elemental carbon (EC) is predominant for OFBs.