In the debate about cars exceeding the legal exhaust limits, we should not forget one simple truth: The tougher these limits are, the more dramatic it sounds when they are broken.
Let's assume legislators set the ceiling for a given chemical compound at just above zero. It's natural, then, that even a small amount of pollution will result in a violation by a factor of tens or even hundreds of times the limit. But that does not mean that, automatically, someone will be poisoned by that amount.
In simple mathematical terms: "Ten times zero is still zero."
One should keep this principle in mind when talking about air pollution in big cities today, in Germany and in Europe. Given the recent public attention to diesel pollution, one might get the impression that we're close to suffocating in all the car traffic here.
But that's not true. Progress in emissions controls has been more than noticeable in recent decades. This applies to cars, power plants and industry. I would even go as far as to say that someone who was born in Germany after reunification - and has stayed in Europe since then - has never been breathing truly bad air (unless inside a hookah lounge).
Considerable reduction in fine particles
Let's take fine particles as an example: At the beginning of industrialization, in the early 18th century, particle pollution in London was at around 260 micrograms per cubic meter of air. This value increased until the end of the 19th century, when it peaked at well above 600. Only in the 20th century was there a turnaround. In the 1950s it came down to below the early industrial level, at 200 micrograms per cubic meter. Today, the level is at just 16. Of course, the German city of Stuttgart, by comparison, has some catching up to do: There it stands at 38. But compared to historical levels, it still looks a lot like "Two-and-a-half times zero."
By the way, during New Year's celebrations, fine particle concentrations in German cities regularly exceed 2,000 micrograms per cubic meter due to fireworks. In just one night, those emissions equal 15 percent of all road traffic in an entire year.
To keep the emissions in perspective, it also pays to look beyond Europe's borders: In Asia and Africa, many big cities have three-digit particle concentrations - similar to those in Europe during the high point of industrialization.
And it is similar with nitrogen oxides (NOx) in our air. In just the short period of time since the 1990s they have gone down to less than half of what they used to be. A big chunk of those emissions reductions are actually due to modern motor technologies. Road-traffic-related emissions have gone down to around a third of what they once were.
Yes, it could be still better - for example, if all diesel cars had active emissions controls using AdBlue (to eliminate NOx from exhaust). This is already working quite well with trucks and is also prescribed by law for sedans. But the fact that we are not quite there yet, due to dieselgate, should nonetheless not blind us to the considerable progress we have witnessed in keeping our air clean in recent decades.
Barbeque, campfires, furnaces, smoking
There are other emissions sources that many people overlook in the debate about cars. Some of them create fumes that are actually much worse: the many barbeques in the summertime, where grease from steaks and sausages hits charcoal; the campfires in gardens and at cottages, where people tend not only to burn clean, dry firewood but perhaps throw in an old piece of painted plywood (or worse, plastics or even a car tire).
Even wood burning furnaces in residential homes do not merit the ecological image most people grant them. Authorities have no way of verifying that inhabitants do not actually burn old furniture. The truth is, no chimney sweep will ever find out during an annual inspection.
And it is enough to spoil the good air in a city if just a few of the many people who own such furnaces abuse them to dispose of their garbage. I am certainly able to judge with my own nose that, during some winter nights, there are many people incinerating things that do not belong inside a furnace. Just one such fireplace is enough to generate more fumes, particles and poisonous substances than all the cars on a much-used urban street.
A similar analogy applies to cigarette smokers: In Germany, they exhaust more dioxin than a specialized incinerator for hazardous waste. But there is one important difference: They usually do so inside their apartments, where the fumes are stuck.
Pay attention to historical context when looking at studies
Now, what about all those studies telling us that hundreds of thousands of people die every year due to car-related air pollution?
First, there are methodological problems inherent in such epidemiological studies. They often fail to clearly lay out cause and effect. Under such circumstances, correlations are notoriously difficult to draw.
But even if we accept the conclusions, a look back at history also makes sense here: Since the beginning of the 20th century, life expectancy has almost doubled, from over 40 years to around 80.
At the same time, the world population has increased from under two billion to more than seven billion. Of course, this also has something to do with modern medicine, nutrition and lifestyle.
But then, shouldn't we ask ourselves about the role motorized mobility has played in all this human and technological development? Creating modern life and the innovative economy that made our long lives possible in the first place?
Then, it may also be legitimate to fully turn the argument on its head.
Maybe, we will one day find out how many lives are saved by car traffic every single year - and not just by firetrucks, ambulances and police cars.