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Real Time Vehicle Emissions pilot project, March 2017

In March 2017, a pilot project was carried out in Edinburgh and West Lothian to measure the pollutants generated by vehicles driving in 'real world' conditions. This was to provide reliable data on the real level of pollutants emitted by vehicles, which was thought to be significantly different to the laboratory conditions under which vehicles are normally tested.

Background: Vehicle Emissions Testing

East Central Scotland Vehicle Emissions Partnership (ECSVEP) was formed in 2004 using Scottish Government annual grant funding. The partnership is administered by West Lothian Council and involves East Lothian, Midlothian and Falkirk Councils. In 2019, Stirling Council joined the Partnership. The partnership was established to increase awareness of vehicle emissions' contribution to poor air quality and its effects on human health.

In the earlier years of the partnership, a significant element of this approach involved voluntary vehicle emissions testing using a mobile testing vehicle. This gave rise to a consistent 15% failure rate of the MOT standard emissions test. 

Background: Strategic

Understanding of vehicle emissions has changed significantly in recent years:

  • Euro 5 standard vehicle emission standards failed to deliver the improvements in air quality intended;
  • Use of diesel powered vehicles continued to rise, due to the perceived reduction in carbon dioxide (a greenhouse gas) emissions over equivalent petrol vehicles;
  • Reports appeared showing that car manufacturer emissions testing regimes produced misleading results;
  • It has become increasingly clear that emissions from real world driving conditions are significantly higher than those obtained under the laboratory conditions used for type approval.

These factors demonstrated a greater need to gather information which will give a better understanding of real world emission levels from vehicles using our roads.

Since the inception of the project, air quality policy in Scotland has moved significantly. The Scottish Government announced plans to have four 'Low Emission Zones' (LEZ) in place to address air quality in the country by 2020, with Glasgow the first to be established at the end of 2018. LEZs are also expected to be established in Edinburgh, Aberdeen and Dundee. From 2023, all Air Quality Management Areas will include a Low Emissions Zone option (where the National Modelling Framework (NMF) shows it to be of value).

Pilot Project

The real time vehicle emissions testing project commenced on the A8 at Maybury on Monday 20 March 2017. Deployment on the A89 at Broxburn commenced on 27 March, with an on-site information event held on Wednesday 29th March. Following the release of funding by the Scottish Government, North Lanarkshire Council secured a two week end on deployment on the A725 at Whifflet. The combined effect was by far the largest deployment to date in the UK and the first in Scotland. 


The most significant outcome was that during the two week trial period, over 73,000 recordings were gathered. The outcomes report [3MB] provided by the equipment supplier can be downloaded.

Considerable differences were found between real world and 'specified' emissions for vehicles. In particular:

  • Diesel vehicle groups on average do not show a reduction in overall Nitrogen monoxide (NO) across the Euro classes. Although the Euro 6 class has a lower average of NO emissions, the levels of NO remain elevated (Report, Figures 4-12 & 4-16);
  • Few of the Euro 6 diesel vehicle groups analysed met the Euro 3 Standards. On average, Euro 6 emissions are only moderately below the in-use levels of Euro 3 to Euro 5 classes; 
  • It was proven in this pilot that the most recent Euro 6 Class diesels, may be emitting more than earlier vehicles;
  • The average NOx (Nitrogen dioxide (NO2) plus Nitrogen monoxide(NO)) emission value of Euro 4, Euro 5, and Euro 6 diesel cars was significantly higher than standards permit;

In broader terms:

  • NO and NO2 is higher for diesel than petrol for all years. (Report Figure 4-34); 
  • NO and NO2 from petrol vehicles generally decreases with each successive Euro Class. It is always lower than for an equivalent year diesel; 
  • Petrol vehicles show no significant trend in particulates with Euro Class, with generally low emissions;
  • Diesel vehicles show a generally higher average for particulates from the older diesel Euro groups (0 to 4) and a lower average for the newer Euro groups (5 and 6). From 2011, diesel vehicles produce less particulates than petrol vehicles;
  • Euro VI diesel buses are particularly good, but a number of relatively high 'outliers' make the average for Euro VI buses higher than for Euro III-V; and
  • 16% of vehicles were operating with engines and exhaust system not fully warmed. A significant proportion of commercial delivery vehicles (diesel van (24%) and diesel ordinary goods vehicles (OGV) (31%)) operate below temperature, producing higher emissions

Gross polluters can be identified where a vehicle has made three or more passes through the system. Significantly:

  • common faults can be identified by comparison with the average figure for the vehicle model; and
  • tackling the worst 5% of vehicles will result in an approximate 10% reduction in emissions.

Data set Availability

The full data set has been shared with both Transport Scotland and academics working for the Department of Transport. The academics will carry out a further, more in depth, analysis of the data which will help inform policy decisions relating to motor vehicle pollution across the UK. Anonymised versions of the full data set for each location are available to download ( Broxburn [5MB]  and Edinburgh [10MB] ). These are large files and will take time to download. It is best to download to a computer rather than a mobile device.