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CLD50 for Ambient Roadside Monitoring
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Air Quality Consultancy


By using our latest instruments and calling on 30 years of experience in automotive emissions, we are able to provide a service consulting on local air quality issues. The instruments we use showcase our unique ability to measure combustion source gases with a higher fidelity than available elsewhere. Response times in the order of 100 milliseconds paired with 5ppb sensitivity (for NO) allow identification of individual passing vehicle emissions from the roadside, spatially revolved mobile emissions and surveying of local road networks. Our primary expertise is in emissions from vehicular sources.

Clean Air Zones (CAZ) & Low Emission Zones (LEZ)

The introduction of these zones can help reduce the NOx in general, but there can be stubborn sites where little improvement is measured.  Cambustion engage in projects where the interaction of road layout, geography, wind direction and traffic flow conspire to create NOx “hot spots” where, for example, the location of the conventional AQ monitoring station is affected by vehicle emissions as they pull away from traffic lights. With fast response roadside NOx measurement, Cambustion are able to identify individual gross emitters and vehicle classes which disproportionately affect the local air quality.  This is often caused by heavy duty diesel vehicles’ SCR exhaust systems performance being affected by gradients, idling and traffic intersections.  In addition, real driving emissions assessment of sample vehicles give additional spatial information to help inform solutions to such problems.

The figure below shows the tailpipe NOx emissions from a PHEV vehicle during a representative route around London. The emission hotspots are due to accelerations following speed bumps.

Speedbumps causing spikes in tailpipe NOx emissions on-board a PHEV

Fleet Vehicle Assessment

Using fast real drive emissions (RDE) measurement equipment, we are able to provide emission contribution from company or council fleets as well as evaluating any emission reduction programs such as aftertreatment retrofit schemes. We have found real world benefits of such schemes can be greatly different to expected benefits however, we are able to advise on usage cases to improve in-service compliance.

The video linked below was generated during the tailpipe measurement of a representative Euro 6 passenger bus. Note the high concentrations emitted during the pull-away from the bus stop, thus exposing waiting passengers to highly polluting exhaust gases.

Euro 6 Bus During Bus Stop Manoeuvre

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Compliance

It has been noted that roughly 90% of inner city pollution is caused by 10% of vehicles. Our analyzers have the capability to help identify vehicles with aftertreatment defeat devices or SCR emulators.

This video demonstrates a method used to rapidly ascertain the aftertreatment system effectiveness of passing vehicles. Fast NOx measurement in conjunction with fast ambient CO2 (coming soon, enquire below) allows calculation of the dilution ratio at the sample point, thus allowing a concentration at the tailpipe to be determined. Combine this information with ANPR to build up a window for expected values.

Using On-Road Measurements to Determine Compliance

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Pedestrian and Cyclist Exposure to NOx Pollution

The portability of Cambustion’s fast response analyzers allows for the equipment to be deployed at “nose height” for the accurate assessment of NO and NO2 being inhaled by cyclists or pedestrians.

Installation of the sample probe at nose height during an inner city cycle allowed us an insight into the real-world exposure to NOx from other road users. The video shows pronounced concentrations from overtaking vehicles. This is the first data of it's kind.

Exposure to NOx During Inner-City Cycle Commute

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