A tale of two policies, part 2

Last year I blogged about the difference between real-world emissions of heavy-duty vehicles (HDV) in the United States and the European Union. The takeaway: two very similar policies on paper can produce dramatically different outcomes in the real world. Real-world nitrogen oxide (NOx) emissions from U.S. trucks are, on average, significantly higher than those of EU trucks, especially in lower-speed city driving. The root cause of this discrepancy, poor policy design, is well understood. Fortunately, California’s Air Resources Board has nearly finalized a much-improved policy to address the issue. Our guess is that the United States Environmental Protection Agency will propose something similar later this year to ensure the entire country is covered.

It’s a different story when it comes to cars. In the course of our work in The Real Urban Emissions (TRUE) initiative we have compiled databases of more than 60 million measurements (and counting) of the exhaust emissions of vehicles on the road in the U.S. and EU, captured using remote-sensing equipment. One thing this data shows (Figures 1 and 2) is that the average (model year 2010 onward) car on the road in the EU emits around 6 to 10 times the amount of NOx emitted by an average car in the U.S., while the EU standards permit emissions only about 1 to 4 times higher than the U.S. standards. Another way of looking at this: the emissions of an average model year 2018 car in the EU are the same as that of a model year 2004 U.S. car. That’s a 14-year lag in real-world emissions reductions.

Figure 1. Average NOx emissions from passenger cars in the EU and U.S. for model years 1995–2018 compared to official emissions standards.

But it’s not a new story. We have known for years that average NOx emissions from EU cars are extremely high. And we have known the cause: high emissions from diesel cars due to poor compliance provisions in the EU regulation. The EU has gone to great lengths to fix that. Every new car sold starting in September 2019 has had to meet tougher rules. There are encouraging signs that the impact on real-world emissions has already been substantial, although we don’t yet have conclusive data (but watch this space).

Figure 2. Relative difference between real world NOx emissions and official emissions values for EU and U.S. passenger cars

So it’s a success story, then? High NOx emissions from U.S. HDVs and EU diesel cars are in the process of being addressed by improved policies, and we all live happily ever after? Not quite. All those high-emitting vehicles don’t disappear once the new policies are enacted. They’ll be on the roads for years or even decades. And the public health impacts will continue to be devastating as long as those vehicles are permitted to drive in populated areas. Elevated diesel NOx emissions contribute to poor air quality, exposure to which can significantly decrease life expectancy and increase risks for cardiovascular and respiratory disease as well as cancer.

So who is going to take responsibility for limiting that exposure? The agencies that developed the poorly designed regulations in the first place? Nope, sorry, outside their scope – they only deal with new vehicles. The vehicle manufacturers that sold the high-emitting vehicles? Sorry, I just fell off my chair laughing. No. Ultimately it will be up to local communities and cities to make sure that these high-emitting vehicles are not permitted to drive where people breathe.

But how? What’s a good ending for this story? I’ve got two.

One measure that has gained a lot of traction in European cities is low emissions zones (LEZs), where a city restricts high-emitting vehicles from entering the most populated areas of the city. These LEZs will be most effective if cities can base policy on data—on knowing the real-world emissions of vehicles. Collecting and publishing real-world emissions data is one of the keys to helping cities to address vehicle pollution exposure.

Then again, there’s a more dramatic conclusion, one that a number of cities have already proposed: ban internal combustion vehicles entirely. Extreme? Maybe. Believable? When cities consistently are left to clean up a mess created by vehicle manufacturers exploiting policy loopholes and can never be sure that what is coming out of those tailpipes is what they’ve been told? Yes. That’s a believable ending. Maybe even a happy one.