According to multiple published reports, a minority of vehicles produce a disproportionate amount tailpipe emissions, often harmful nitric oxides. Historically, it has been tough task to indentify which vehicles are actually the most polluting beyond targeting vehicles by age.
The use of fast-yet-sensitive roadside NOx and CO2 analyzers, we are able to identify each passing vehicle and determine which are emitting a disproportionate amount of pollutants. The response times for the instruments in question are below 100ms, meaning multiple vehicles can be surveyed in rapid succession. Combining this emissions data with ANPR then allows for NOx/CO2 pollutant bands to be drawn based off of emissions classification. Gross emitters stand out from their category due to a high NOx/CO2 ratio.
These gross emitters can then be targeted by enforcement agencies or local bodies with the aim of reducing human exposure and addressing public health concerns.
This video demonstrates a method used to rapidly ascertain the aftertreatment system effectiveness of passing vehicles with NOx only. It shows how sampling location proximity leads to stronger measurement concentrations.
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