This highly non mathematical post was written during a period of intense fog in Trieste, in northern Italy.
According to the WHO, an astounding 99% of the worlds population live with breathes air that exceeds WHO air quality limits (source), which can partially explain why the same WHO sets air purifiers as one of the most important initiatives for improving the population health. They further estimate that around 6.8 million people die prematurely because of air pollution every year (source), but it is also linked to various other types non-lethal conditions such as dementia/Alzheimer’s disease and chronic inflammation and many many more (source).
In Trieste this wave of polluted air came under the guise of a friendly grey cloud. A cloud that mysteriously did not move the hygrometer. The following picture is from the European Environmental Agency’s (EEA) own webpage:
If one views their ranking (link) today unfortunately confirms the bleak trend shown in the picture above. Among the European cities ranked by air quality on this site, 5 out of 6 of the worst cities are in northern Italy (Cremona, Padova, Vicenza and Venezia), which have had dangerously high levels of PM2.5 and nitrogen dioxide particles for several weeks now, the smallest particles and the most hazardous to the health. In fairness, the worst city on the ranking is Nowy Sacz in Poland, where coal is still burnt in many households for heating (link).
Historically, the trend seems to be the same. In 2020 the court of justice of the European union reprimanded Italy for not having managed for to meet the European Directive standards for air quality (link). Why? Worries over financial repercussions trumped the need to safeguard the health of population. In this article the the situation is explained in more details. Also interesting correlations with the covid pandemic are studied, linking air pollution with the high mortality rate and spread of the infection. It is argued that the stringent restrictions on movement during the COVID-19 pandemic significantly improved the air quality in Italy, though the industrial machinery kept working. This suggest that most of the smog seen in and around cities are produced by vehicles on the road.
Now, let me try to explain the title of this post. Having somewhat honed inn on vehicles as the main culprit for the smog, there still remains a big question as to why is this worse in Italy than other “comparable” countries. I mean, most cities have a constant buzzing of cars. Further digging brought the following article to my attention. It compares the average air pollution of the two-stroke engine and claims that this type of engine releases about 124 times as many particles into the air. A summary in italian can be found on Le Scienze.
The two stroke engine has now fortunately been out of fashion in Europe, maybe due to a European Directive from 2017, colloquially referred to as “Euro 4”. There is also a more recent Euro 6, but as I understand it, this new directive does not put any further restrictions on two wheelers. It is said that mostly older scooters have these types of engines, but what goes for old is rather relative. The Vespa for instance, kept producing a model with the 2 stroke engine up till around 2013, which means there are more than a few still on the road. So each one of these old classics pollute as much as 124 cars (or around 40 if we correct for the difference in fuel consumption, as a scooter generally uses 1/3 of the amount of fuel as a regular car).
Combining this with the fact that Italy has the highest number of scooters per capita than any other European country (link), with a whopping 26% of all households owning at least one, it may be a reason to suspect this alone could explain the higher values of pollutants in the air. Maybe this was in the mind of the legislatures of the 2019 “anti-vespa law” of Genoa (link), which prohibited the use of scooters made prior to 1999. How many comply with the new legislature is still an open question.
But the 2017 directive fixed the problem as most scooters are now using the 4-stroke engine… well looking at the previous picture and data, apparently not completely. One possible reason is that even the new scooter engine cannot be said to be comparable with that of a car. As this article shows, the average 4-stroke scooter emits 4 to 8 times as many hydrocarbons out into the air as a regular car. A huge improvement over its 2 stroke predecessor, but still quite a lot higher. The reason why is obvious – the laws dealing with emissions as simply more relaxed for scooters and motorcycles than ordinary cars.
Being the proud owner of Moto Guzzi V9 Bobber, a motorcycle I chose also for the low “noise pollution” produced by the pretty quiet engine, it is not hard to relate to the convenience and freedom that a scooter can give, especially when trying to park creatively in an overcrowded city. I was aware of the fact that my engine would be slightly more exhaust producing, but did not think it would be worse than a car. I think most people are simply unaware of the problem and hence unable to make informed decisions.
I have to emphasize, the problem here is the waste particles in the exhaust coming out from the vehicle, not the overall fuel consumption. The former is a problem for the local environment, the latter is a problem for the global environment. For those living in the countryside with little or no traffic, a two-wheeler would be a better option for the climate due to its lower carbon dioxide emissions.
For now it seems the best option is to get a good air purifier for the house, preferably with an active carbon filter for the various gasses (carbon monoxide, sulfur oxides, nitrogen oxides, and ground level ozone) that a HEPA filter will not remove, and to keep the windows closed. Alternatively air out the apartment quickly then clean the air with the purifier.