Euro 7 has finally arrived
As the saying goes, a ‘good’ landing is one from which you can walk away, but a ‘great’ landing is one after which they can use the plane again. Euro 7 has not just landed safely, but the craft that is the European system of emissions regulation remains viable. It required a deft touch. The industry says it is too tough and environmental campaigners say it is too weak in equal measure, which perhaps reflects the achievement.
It could have so easily have been otherwise. Of course, there will be arguments around the pollutants included, boundary conditions and limit values – and some reservations will be expressed below. Where it could have gone badly wrong is if these pollutant regulations had been hijacked as an ersatz greenhouse gas emissions regulation. It is not the role of the Euro regulations to take a position on carbon dioxide (CO2) or other climate change gases, but rather to ensure that whatever is on the road does not emit excessive air pollutants. Equally, it could have erred by taking a line disproportionate to the costs and benefits of air pollutant reduction, with the intention of making particular technologies – in this case, internal combustion engine (ICE) and hybrid vehicles – uneconomic. There must always be a proportionality in pollution abatement to achieve the optimal outcome.
Looking at the big picture, it is important to be clear where most air pollution from road transport now comes from. It is mainly from old cars, not new ones. Euro 7 can only affect the cars of the future, not fix the issues of regulatory failure and industry behaviour of the past, as illuminated by Dieselgate. It would be a highly sub-optimal approach to make new cars disproportionately clean to offset the disproportionate excesses of the past. This would seriously impair the new car market leading to owners keeping the older, dirtier cars on the road longer. Where pollution does arise from new cars, it is not from diesels. Not only do nitrogen oxide (NOx) emissions across all diesels from the introduction of the on-road Real Driving Emissions (RDE) regulation average just 43 mg/km on Emissions Analytics’ independent real-world testing, many are now well below 20 mg/km. This is two-thirds below the new limit proposed for Euro 7. Further, the market share of diesel passenger cars is below 10% in many countries, even counting mild hybrids, so the aggregate effect of diesels is small. Rather, gasoline vehicles make up around two-thirds of new car sales in most developed countries, a proportion of which have elevated ultrafine particle and volatile organic compound (VOC) emissions, which will be addressed to some extent by Euro 7.
Tackling pollution from older vehicles, which has such an important bearing on overall emissions, has two main strands. Where it is right for Euro 7 to play a role is in the durability requirements on the car manufacturer, which Euro 7 extends to up to 200,000 km and 10 years from new for each vehicle. During this period, vehicles must meet the emissions limit at certification, with some allowances for deterioration. To be effective, surveillance and remediation must be actively applied. In parallel with this, countries run local ‘periodic technical inspection’ programmes to check vehicles in the field. Enhanced programmes have been introduced in countries such as the Netherlands. Using particle number counters at inspection centres can spot compromised particle filters effectively. Similar test could also be applied to NOx emissions to detect issues with Selective Catalytic Reduction (SCR) – aka AdBlue or DEF – systems. So, Euro 7 is tightening the durability requirements, and must ensure proper surveillance, but it cannot be expected to police all cars on the roads in every country.
Setting aside issues of the geriatric decline of vehicles, there remain two big contributors to air quality problems. First, almost all ICE vehicles before 2009 had no particle filter and therefore still contribute to ambient PM2.5 exceedances. As they continue to age, this problem is likely to get worse through component degradation, only offset as those vehicles finally depart the car parc in growing numbers. The second, more vexatious, problem is those light-duty diesel vehicles from 2009 to 2019 which had real-world NOx emissions multiple times the limit value. For example, the average NOx emissions for pre-RDE Euro 6 vehicles is 418 mg/km, or 5.2 times the 80 mg/km limit (but recall that the 43 mg/km for the later Euro 6s!). Despite software recalls on certain models since Dieselgate, the problem remains widespread as almost all manufacturers generated exceedances. Euro 7 cannot play a role in the second problem as it is an outstanding legal one, but it could have made the first problem worse by impairing the new car market and the natural updating of the vehicle parc.
So, Euro 7 has deftly avoided being drawn into areas it was not designed for. Not only does that avoid the distortions that would have arisen, but it leaves the integrity of the system intact – notwithstanding the flesh wound of pre-RDE Euro 6. It has also made the overdue leap towards technology neutrality, as it should always have had, to avoid behavioural distortion. This means that Euro 7 will be seen as a serious and relevant regulation internationally, and it has also set the stage for future regulatory stages for electric vehicles with the inclusion of the template for limit values for brake and tyre wear emissions. The introduction timetable should also be noted: despite the delays in announcing the Euro 7 proposals, the introduction will be relatively swift, which is valuable to draw a close to the sickly mutant that is Euro 6.
Turning back to the specific questions of the pollutants included, boundary conditions and limit values, we can offer a perspective from Emissions Analytics’ testing. Quite rightly, an N2O limit is excluded from the passenger car proposals as our real-world testing on both gasoline and diesel vehicles has shown it to be a relatively small problem. The widening of the boundary conditions – for example to require compliance in a wider range of conditions, such as up to ambient temperatures of 45 degrees Celsius – goes hand-in-hand with the tightened limit values. In short, both are tightened a couple of turns, but for most manufacturers these should not present a big hurdle. On most pollutants, the latest vehicles are well below the proposed limits, whether it is the diesel NOx emissions stated earlier, of the average real-world carbon monoxide (CO) emissions of 158 mg/km on new gasoline vehicles compared to the Euro 7 limit of 500 mg/km. The proposed ammonia (NH3) limit of 20 mg/km should be easily met as our testing shows results typically in the 5-15 mg/km range already. The widened boundary conditions add to the challenge, but evidence is that existing exhaust treatment in the form of particulate filters, SCR systems and oxidation catalysts can be calibrated to handle.
Does this mean, therefore, that Euro 7 will unfold smoothly? In the short run, it probably will, but it sets the scene for the coming battles which will be primarily around ultrafine or nanoparticles, and VOCs from multiple sources on vehicles. Euro 7 expands the measurement of tailpipe particles including those with a diameter as low as 10 nm, compared to 23 nm previously. As a result, this will bring in tiny, semi-volatile particles that have previously been hard to measure repeatably. On VOCs, the passenger car regulation includes a limit for non-methane hydrocarbons (NMHC) and well as total hydrocarbons (THC). The heavy-duty regulation goes further as includes formaldehyde (CH2O), a known carcinogen.
A tension in the Euro 7 proposal is that, while more tailpipe nanoparticles are being brought in scope, for brake and tyre wear emissions only a mass-based standard is being proposed. This will mean that nanoparticles from brakes and tyres will effectively be ignored, as they are large in number but almost mass-less. For the same reasons that tailpipe nanoparticles are being carefully regulated, so should those from brakes and tyres. However, the inclusion of brake and tyre wear at all is a significant step forward – a starting rather than end point.
Euro 7 should also be more specific on the VOCs that it intends to regulate. First, VOCs are a wider set than just the hydrocarbons currently covered. Second, VOCs form an unbounded set of compounds with significantly different environmental and health effects. These effects including the primary health effects from direct exposure, as well as the propensity of them to form both ground-level ozone and second organic aerosol particles – both significant air pollutants. Grouping them together may make measurement is easier, but much less effective. As Emissions Analytics has previously shown, it is now possible to measure a wider range of these VOC species in real-world conditions. Beyond the tailpipe, attention must also be paid to the VOCs that off-gas from vehicle tyres and what VOCs may leach out into water and soil as tyre particles settle. Whatever the source, models have been developed to estimate the “ozone formation potential” (OFP) and “secondary organic aerosol” yield (SOA Yield) from emitted VOCs. In a recent paper by Wang et al, ten different VOCs were studied inurban Shanghai. For OFP, the range was from 1.09 to 15.11, where these values were the ratio between the ppb of ozone produced fromthe same ppb of the VOC. The highest OFP was from ethene and the lowest 1-butene. For SOA Yield, the range was from 0.05 to 4.01, measured in µg/m3, with the highest being toluene and the lowest 1,2,4-trimethylbenzene. Therefore, the ratio of effect from the highest to lowest within just these ten compounds was 14 for OFP and 80 for SOA. This is why the speciation of VOC measurement is vital for air quality control, rather than relying solely on the aggregated NMHC or non-methane organic gas (NMOG) values.
Finally, it is only one more step then to consider the pollutants accumulating inside vehicles, as we have discussed in previous newsletters. Here, again, it is primarily a question of nanoparticles and VOCs – the former entering from pollution outside, and the latter off-gassing from interior materials. To standardise measurement of particle ingress, the Comité Européen de Normalisation (CEN) has recently published a new method, CWA1793, which was initiated by the AIR Alliance and to which Emissions Analytics contributed test data.
In summary, Euro 7 has neatly tightened the regulations where necessary, tidied up most of the problems of Euro 6 and set the platform for future emissions regulation from vehicles, rightly taking a more holistic approach. Applied well, it could ensure fair competition between types of powertrain, stimulate a healthy new car market to freshen the parc, and avoid storing up unintended consequences of electrification. It makes initial, but important, steps towards a greater focus on nanoparticles and VOCs. Whether that leaves ICE vehicles as a generic class with any future will rightly be determined not by Euro 7 but by the fleet-average CO2 targets and primarily legislation around permitted vehicle types. Maybe Euro 7 will deliver an important message to those other legislators: define the environmental objective and not the means, and let the automotive market weave its magic.