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Total Diesel Exhaust Particulate Length Measurements Using a Modified Household Smoke Alarm Ionization Chamber

ABSTRACT To evaluate the effectiveness of various means to combat the negative health effects of ultrafine particles emitted by internal combustion engines, a reliable, low-cost instrument for dynamic measurements of the exhaust emissions of ultrafine particulate matter (PM) is needed. In this study, an ordinary ionization-type building smoke detector was modified to serve as a measuring ionization chamber and utilized for dynamic measurements of PM emissions from diesel engines. When used with diluted exhaust, the readings show an excellent correlation with total particulate length. The instrument worked well with raw and diluted exhaust and with varying emission levels and is well suitable for on-board use. IMPLICATIONS The findings suggest the possibility for dynamic PM length measurements in diesel engine exhaust using a simple instrument using an ionization chamber analogous to the ionization chambers used in household smoke detectors, which are mass-produced and readily available on the market at costs in the $10–50 (U.S.) range. Such an instrument could be used on-board or in a test facility for qualitative online measurements and for discrimination between pre-diesel particulate filter (DPF) and post-DPF levels and identification of high-emitting vehicles, becoming a tool analogous to the garage- and inspection-grade opacity meters and exhaust gas analyzers.