Carbonaceous particulate matter (PM), comprising black carbon (BC), primary organic aerosol (POA) and secondary organic aerosol (SOA), is a highly toxic vehicle exhaust component. SOA is formed in the atmosphere from photo-oxidation of precursor gases. On-road gasoline vehicles are an important source of SOA precursors in urban environments. Understanding vehicle pollution requires knowledge of both primary emissions, and how these emissions age in the atmosphere.
SOA formation can be quantified from a fleet of on-road gasoline vehicles using a Potential Aerosol Mass (PAM) Oxidation Flow Reactor (OFR). SOA formation determined by dynamometer driving cycle (especially cold starts) with OFR and experiments using real-world vehicle exhaust (from a roadway tunnel or busy roadside) are important in characterizing SOA formation in the laboratory from actual emissions. The effect of co-emitted sulphur species on oxidation chemistry/ products and night-time oxidation with NO3 radical are openings for additional research. Tightening of emissions standards reduces SOA production from on-road gasoline vehicles. The modern engine designs require low sulphur fuels to maintain robust emissions performance throughout their useful lifetimes. It is due to this fact that the single most important fuel parameter specified in the BS VI regulation is the 10 ppm limit on sulphur content of gasoline and diesel fuels. Access to ultra-low sulphur fuels enables the introduction of modern, low-emitting BS VI vehicles that incorporate best available technologies for the control of air pollutant emissions.
SOA production in the PAM reactor depends on multiple factors, including background concentrations, organic aerosol concentrations, and hydroxyl radical (OH) concentrations. These factors can vary widely from vehicle to vehicle and between different engine operations (e.g. cold versus hot starts), which complicates interpretation of the PAM data and its use as a screening tool for SOA formation potential from vehicle exhaust. The Aerodyne OFR with its continuing improvements, creates the possibility for routine PAM quantification from the multipollutant emissions of common sources.
We hoped you enjoyed our webinar “Formation and Oxidative aging of Secondary Organic Aerosols (SOA) using the Potential Aerosol Mass (PAM) oxidation flow reactor” as much as we did!
If you weren’t able to make it, catch our replay.