High spatiotemporal resolution pollutant measurements of on-board vehicle emissions using ultra-fast response gas analyzers

Existing ultra-fast response engine exhaust emissions analyzers have been adapted for on-board vehicle use combined with GPS data. We present, for the first time, how high spatiotemporal resolution data products allow transient features associated with internal combustion engines to be examined in detail during on-road driving. Such data is both useful to examine the circumstances leading to high emissions, and reveals the accurate position of urban air quality “hot spots” as deposited by the candidate vehicle, useful for source attribution and dispersion modelling. The fast response time of the analyzers also enabled accurate time-alignment with the vehicle’s Engine Control Unit (ECU) signals enabling correlation with transient air fuel ratio, engine speed, load, and other engine parameters. This helps to explain the causes of the emissions “spikes” which conventional slow response analyzers would smooth out due to mixing within their sampling systems. The data presented is from NO and NO x analyzers, but other fast analyzers (e.g. Total Hydrocarbons (THC), CO and CO 2 can be used similarly. The high levels of NO x pollution associated with accelerating on entry ramps to motorways, driving over speed bumps, accelerating away from traffic lights, are explored in detail. The time-aligned ultra-fast analyzers offer unique insight allowing more accurate quantification and better interpretation of engine and driver activity and the associated emissions impact on local air quality.