Is Milan really the third most polluted city in the world?

On Sunday 18 February the Swiss company IQAir published a report on air quality in various cities around the world, drawing up a classification of those in which it is most polluted, in which Milan appeared third behind only Chengdu in China and Lahore in Pakistan.The list caused quite a stir, quickly becoming one of the most debated topics of the moment;Mayor Beppe Sala, questioned by journalists, provided one answer annoyed and hasty on the issue, rhetorically asking her interviewers who conducted this type of analysis, to underline the unreliability of the data coming from private entities and invite you to trust official data.Indeed, it seems difficult to imagine that Milan could place itself on the podium of the cities with the worst air quality in the world, above very large centres like New Delhi;However, this does not mean that the ranking provided by IQAir provides an interesting point of view which is worth reflecting on, which places us before the evident problem of air pollution in Milan, Lombardy and in the Po Valley, precisely in light of the "official data" cited by Mayor Sala.

IQAir's report supports its own analyses on official surveys, in the case of Milan provided by ARPA Lombardy, and on a private “crowdsourced network” managed directly by the company.To draw up its ranking, IQAir takes into consideration six different polluting factors (PM2.5, PM10, ozone, nitrogen dioxide NO2, carbon monoxide CO and sulfur dioxide SO2), focusing mainly on PM2.5, i.e. fine dust particles with dimensions less than or equal to 2.5 microns present in the air, and compiles a score called IQA (Air Quality Index).For various reasons, IQAir's analyses they leave whatever time they find:as specified by the company itself, the ranking drawn up takes into consideration only 111 cities with more than 300,000 inhabitants spread around the world, an element which for obvious reasons can only provide a partial ranking of the IQA;it should also be considered that, when presenting the analyses, the source of the data and the way in which the index is calculated are unclear;finally, it should be underlined that conducting comparisons on air quality between different cities in the world is much more difficult than it seems, because there are many elements to consider and each country presents different measurement standards from others.

Despite the obvious bias of the IQAir data, it must be specified that the same Swiss company he did not intend to draw up a complete ranking and all-encompassing.In the presentation of the analyzes we can read how "the objective of the ranking of large cities is to provide a way to perceive regional air quality in a global context.The list contains one or more cities per country, but is NOT intended to include all cities in the world", in fact "not all cities exceeding 300,000 inhabitants are included, because the list seeks to ensure a complete representation of various locations in the whole world. Allow meaningful comparisons”.In short, it seems that, speaking in the media, they wanted to build a case out of nothing, ignoring the real intentions of the Swiss company, which he never said that Milan is the third city with the worst air in the world.In any case, whether IQAir was in good or bad faith, its personal ranking only confirms a problem of undoubted relevance and urgency, which is precisely that of the air quality in the Po Valley, which is one of the most polluted areas in the world.

It is precisely for this reason that yesterday, February 20th, the anti-pollution regulations in 9 Lombardy provinces, which will include a ban on the combustion and lighting of fires outdoors, the limitation of transit of all Euro 0 and 1 vehicles and Euro 2, 3 and 4 diesel vehicles in all municipalities of over 30,000 inhabitants in the time slot 7.30 - 19.30, as well as more extensive traffic restrictions on Saturdays and Sundays, and more stringent rules on heating.Although Mayor Sala bluntly said that "the air has improved", Legambiente believes that the air quality is not never been so dangerous since winter 2017.Effectively from January to August 2023 in 58 different Italian cities the concentration of fine particles has exceeded the limits suggested by the WHO, and many of them are found precisely in the Po Valley, which, taking all of Western Europe into consideration, is the area with the higher number of premature deaths related to pollution.

If we restrict the area to Milan alone, we can see how on 18 February, compared to 118 micrograms per cubic meter of PM2.5 and 136 of PM10 at the control unit in via Senato, peaks never recorded since January 2017 were reached, while on February 19 with its 80 micrograms per cubic meter of PM2.5 and 122 of PM10, the daily average limit established by the WHO has been overcome by more than 3 times and just under 3 times respectively.The situation is no different if we look at the Cremona area, the Lodi area, the Mantua area and the Pavia area, so much so that in general, as Legambiente recalls in its latest Mal'aria città report, "18 cities out of 98 have exceeded the daily PM10 limits ", of which 16 located near the Po basin and 6 Lombard.In short, although Milan is not the third city with the most polluted air in the world, as stated by the general director of Legambiente Giorgio Zampetti, "the data released by IQAir on the quality of Milan's air must be contextualized in a broader and more complex scenario of what emerged today, otherwise we risk causing confusion and losing sight of the real critical issues but above all the air quality improvement objectives to be achieved".

[by Dario Lucisano]