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Guest article by Dr Alessandro Borgini, ISDE – Italy 

Decades of important scientific studies have revealed the strong connection between exposure to air pollution and adverse health outcomes like respiratory infections, heart disease and lung cancer. Both short- and long-term exposure to air pollutants has been associated with health impacts, and the International Agency for Research on Cancer (IARC) has classified outdoor air pollution and particulate matter (PM) as carcinogenic to humans. 

As a result, the last decades saw an increase in policies aiming to reduce air pollution and improve air quality both at the European as well as Global levels, thus reiterating the urgency for action. In September 2021, the World Health Organization (WHO) updated its global air quality guidelines for particulate matter (PM₂.₅ and PM₁₀), ozone (O₃), nitrogen dioxide (NO₂), sulfur dioxide (SO₂) and carbon monoxide (CO) to better protect the health of populations. For instance, the WHO now recommends a maximum level of 5 μg/m3 for fine particulate matter (PM2.5) for long-term exposure to protect health. 

These Guidelines are addressed to all countries of the world and provide uniform targets for air quality. The new targets are much stricter than most national standards in force in many parts of the world, which in some cities would mean a more than threefold reduction in the current level of pollution. 

Exposure to fine particulate matter (PM2.5) caused approximately 307,000 premature deaths in 2019 in the European Union (EU) alone, despite its annual limit value for fine particulate matter (PM2.5) of 25 μg/m3 set in 2008. This Ambient Air Quality Directive 2008/50/EC is currently under revision to, among other things, align the EU standards more closely with the WHO recommendations. Currently, air quality is categorised as: 

• good - for levels of fine particulate matter that do not exceed the annual guideline value of the World Health Organization of 5 μg/m3, 
• fair - for levels above 5 and not exceeding 10 μg/m3 
• moderate - for levels above 10 and not exceeding 15 μg/m3; 
• poor - for levels above 15 and not exceeding 25 μg/m3;     
• very poor - for levels at and above the European Union limit value of 25 μg/m3. 

For example, for fine particulate matter (PM2.5), two Italian cities, Cremona, located to the north in the Po valley area, and Padua, to the northeast, exceeded the threshold of 25 μg/m3 in 2020 and 2021. Also, 23 Italian cities, such as Milan, Brescia, Bergamo, Pavia, Venice, Vicenza, Turin, etc. have poor air quality (between 15 and 25 μg/m3). 

If the new WHO limits for PM2.5 were applied to Italian cities, most of them would exceed this limit. Therefore, European air quality laws must comply with the limits proposed by WHO. A more ambitious European Ambient Air Quality Directive will push local authorities to increase sustainable mobility, reduce emissions of pollutants from traffic and heating, and a real expansion of urban green space in each city, with the planting of trees. This would reduce pollutants such as PM and nitrogen oxides (NOx), and of course increase CO2 sequestration. The revision of the Ambient Air Quality Directives is thus an opportunity to improve our cities and save many lives!