PAHs and their Carcinogenic Potencies in Diesel Fuel and Diesel Generator Exhaust

ABSTRACT

The PAH profile was characterized in diesel fuel samples collected from different service stations in Agra (India) by using a gas chromatograph equipped with a flame ionization detector (FID). The low molecular weight PAHs were predominant, ranging from 4.4 × 10² to 1.7 × 10³ mg l^{− 1} in fuel. Exhaust emissions from a diesel generator and a four-stroke engine (Skoda) powered by these fuels were monitored by a stack sampler and quantified for PAHs. The high molecular weight PAHs (DbA+IP, BghiP, and BaP, BbF+BkF) were the dominant PAHs in exhaust emissions. Differences in PAH emission factors for the two engines were found and these differences could be related to the combustion conditions affecting the temperature of flue gas. Emission factors and output/input ratio for individual PAHs suggest that the low molecular weight compounds in the fuel contribute to pyrosynthesis of high molecular weight in exhaust. Unburnt fuel partially contributes to low molecular weight PAHs in exhaust. Further, the relative carcinogenic contributions of each compound in the fuel and exhaust were calculated using the TEF approach. DbA + IP and BaP were significant contributors to the carcinogenicity of the PAH mixture in the exhaust.

Key words:

• PAHs
• fuel exhaust
• engine exhaust
• emission factors
• carcinogenic potencies

ACKNOWLEDGMENTS

The authors are grateful to the Director, Dayalbagh Educational Institute Agra; Head, Department of Chemistry, and Head, Heat Engines Laboratory, for providing necessary help; and the Department of Science and Technology, DST project No.: SR/S4/AS:207/02, New Delhi, for financial assistance.

Notes

*Emission Factor (mg/l) = [PAH concentration ((μ g m^{− 3}) × Flow rate of exhaust gas (m³ min^{− 1})/Fuel consumption (ml min^{− 1}).