AIR Index: lifting the fog on smog


The ‘dieselgate’ scandal highlighted a crucial need for change around how cars are tested and how much they actually emit on-road in urban driving. With the introduction of clean air zones in many cities, vehicle selection based on choosing those with the lowest emissions is crucial – but are we getting it right? We asked Nick Molden, co-founder of AIR, to explain the newly launched AIR Index

Air quality and the link to vehicle emissions has never been higher on the agenda. For years, the focus has been on CO2 as a greenhouse gas, but more recently awareness of NOx and its harmful effects has increased. NOx impacts our health and the environment, it causes chronic lung disease, damages trees and plants and in extreme cases, forms smog. And nowhere is the problem more prevalent than in cities.
The desire to reduce NOX pollution to improve the health and wellbeing of the millions who live in urban areas has led to the introduction of low-emission zones – measures that control access for the highest polluting vehicles or completely bans them from certain areas. The principle is a sound one: remove the dirtiest vehicles from the worst affected areas. Unfortunately, determining which vehicles are causing the problem is unclear because much of the information being provided is not accurate or truly independent. Until now, policymakers and vehicle buyers have lacked a scientifically rigorous, independent test to measure actual NOX pollution during on-road driving.

Here at AIR, we have worked with an expert academic and industry group to develop the AIR Index, a database of on-road vehicle emissions, using a simple colour-coded visual scale from A to E that indicates the difference between ‘clean’ and ‘dirty’ vehicles. Our intention is to finally clear up the NOX issue for policymakers and consumers – and to help fleets reduce TCO too.

At its core, the AIR Index is a rating scheme based on the robust testing regime conducted in accordance with CWA 17379 – the European guidelines on real drive emission test methodology. The AIR Index shows ‘at a glance’ how clean a vehicle’s tailpipe emissions are, enabling easy comparison for informed decision making.
Inspiration from safety ratings

The inspiration behind the AIR Index was NCAP, the independent vehicle safety rating system developed in the US during the 1970s. It became an industry standard in the EU and throughout the world, holding vehicle manufacturers accountable for the safety performance of their products thereby encouraging widespread innovation and adoption of safety technologies. The AIR Index is intended to provide the same encouragement for the reduction of NOX, by increasing demand for cleaner vehicles and discouraging the purchase of high-polluting models.

The AIR Index is more informative than than current tests including WLTP (World Harmonised Vehicle Testing Procedure), which is still laboratory-based, and RDE (Real Driving Emissions), which although based on real-world emissions, doesn’t truly come into force until September and will only assess new cars from that point onwards. While a step in the right direction, RDE is not much help in identifying the dirty vehicles that are already on our roads.
One of the major findings from our testing is that although a car may adhere to Euro 6, there are enormous discrepancies between on-road emissions and the figures obtained from the vehicle’s type approval. By focussing on the real-world usage and emissions we get a much clearer picture of the vehicle parc. Not all Euro 6 models are the same, and not all diesels are automatically dirty. In fact, some diesel cars are cleaner than petrol models and some newer vehicles actually emit more NOX than older ones.

Testing methods

The testing itself is carried out with a minimum of two vehicles, each sourced independently from the vehicle manufacturer and equipped with Portable Emissions Measuring Systems (PEMS). The vehicles are then driven on a minimum of five, 10km trips spread across three separate journeys. The PEMS are used to gather data on the actual on-road emissions from each vehicle, with the results averaged to determine the AIR Index rating.
In the same way that the AIR Index is designed to provide transparent information for consumers, it is a vital tool for fleet managers too. It allows you to make an informed decision about your car purchases, minimising your fleet’s real-world emissions. It also allows you to identify which of the vehicles in your current fleet are significant polluters.
But company car taxation is based on CO2 emissions and congestion charging while London’s ULEZ, is based on EU emissions standards, so how is the AIR Index relevant?
The relentless and entirely appropriate focus on urban air quality is driven by European fines (in their billions) to punish cities who continue to allow over-emitting vehicles un-restricted access. ULEZ is one response, but the results of future urban air quality monitoring may not show sufficient progress, and the fines will continue. Combine this with public pressure as more vehicles are banned, it is likely that policies based on the actual emissions (shown in the AIR Index) of vehicle, rather than the crude Euro standards, which still permit high emitting cars in, will soon follow.
The consequence of this scenario will be limited access for the high emitting vehicles to urban areas, and hence residual values weaker for these cars which will no longer be attractive when de-fleeted. Fleet managers need to stay ahead of the issue, be aware of the risk and procure only vehicles that they KNOW to be low emitting, in order to mitigate potential future losses and ensure that their drivers continue to have free access to urban areas.

Fleet benefits

Fleet policies based solely on data sources such as CO2 and Euro standards don’t provide an accurate measure of on-road vehicle NOx emissions, and need to evolve to embrace them. Effective management of car choice by actual, on-road NOx emissions will become critical as access to towns and cities for only the cleanest vehicles will become part of the operational landscape.
The AIR Index provides fleet managers with a reliable, trusted and independent framework to inform fleet policy and control TCO. The scientific results of on-road emissions reveal that some diesel engines actually produce lower NOx emissions than petrol engine variants and the AIR Index provides clarity when developing a robust fleet policy.
In selecting vehicles that perform well on the AIR Index, fleets can choose the cleanest cars when making new purchases, and de-fleet the dirtiest.
Indeed, an obvious side-effect of Dieselgate was the significant backlash in attitudes towards diesel vehicles, which influenced decisions on key fleet purchases. In some cases, this was an appropriate reaction, but many modern diesel vehicles are very clean and emit little NOX, even when compared to petrol-powered counterparts. Euro 6 is moving feast and, as a well-informed fleet manager, you will know that there have been continual updates to vehicles from Euro 6C to Euro 6DTemp.

However, how many fleet drivers would guess that a 2018 Land Rover Discovery 3.0 TD6 gets an ‘A’ rating in the AIR Index, emitting twenty times less NOx than a 2017 Renault Clio 1.5 DCI, which gets an ‘E’? Provided you pick the cleanest, diesel most definitely has a place on your fleet, allowing you – and your drivers – to enjoy all of its efficiencies. Thanks to the AIR Index you can now identify and reintroduce low-emission diesel models based on accurate information.

The AIR Index currently has A-E ratings for the first 200 vehicles to have been tested and we are rapidly testing more and more, the results of which will be continually added to the database over the coming weeks. In the not too distant future, your fleet may well consist entirely of zero emission plug-in vehicles and we might not be so concerned about what comes out of the tailpipe of a car – if it even has one. But that scenario looks to be quite a long way off and right now there is a major problem with urban air quality. The good news, though, is that the technology to help clean up our cities is already here and thanks to the AIR Index you can choose to put the cars on your fleet that can be part of the solution, not the problem.