These particles are so tiny that they can penetrate deep into the respiratory system, reaching the alveoli and spreading into the bloodstream. Research indicates that prolonged exposure to PM2.5 dust can have harmful effects on health, including cardiovascular and respiratory problems, asthma and reduced lung function.
Fine dust is produced mainly by combustion of various kinds, such as that from internal combustion engines, thermal power stations, the burning of biomass and coal for home heating, as well as by industrial processes involving emissions that are not fully filtered.
How should we measure this concentration of particles? The unit for measuring the concentration of PM2.5 is the microgram per cubic metre (µg/m³). This unit expresses the mass of suspended particles in each cubic metre of air, making it possible to assess air quality and monitor pollution levels in line with the public health guidelines set by the WHO.
The World Health Organization (WHO) has established that the tolerable annual average of PM2.5 should not exceed 10 µg/m³, while the legal limit is higher, at 25 µg/m³.
In the global context of 2024, a worrying picture emerges regarding the concentration of PM2.5 fine dust around the world, with some countries showing excessively high levels.
In 2024, based on data recorded in the previous year, the five most polluted countries in the world, by average concentration of PM2.5 fine dust, are:
- Bangladesh - With a PM2.5 concentration of 83.3 µg/m³, Bangladesh far exceeds the levels recommended by the World Health Organization, highlighting serious air quality problems that pose a risk to the health of the population.
- Pakistan - Pakistan records a PM2.5 concentration of 65.81 µg/m³. Air pollution in the country is aggravated by factors such as industrial emissions and vehicle pollution.
- Mongolia - Mongolia has a PM2.5 concentration of 62.00 µg/m³, largely due to the heavy use of coal for heating during the cold months, especially in Ulaanbaatar.
- Afghanistan - Afghanistan has an average PM2.5 concentration of 58.80 µg/m³. Air quality is strongly affected by sandstorms and by the burning of solid fuels for heating and cooking.
- India - Completing the top five, India has a PM2.5 concentration of 58.08 µg/m³. Air pollution is driven by industrial activity, vehicle emissions and biomass burning.
You may be wondering how we are doing in Italy. Fortunately, not badly: we are very far from the values in the unfortunate list above. The monitoring data for 2023 even make us moderately optimistic, given that the trend compared with previous years seems to be towards a decrease in airborne particles. Indeed, according to the SNPA, “The annual limit value, equal to 25 µg/m³, was met at all stations but one (311 stations out of 312, or 99.7% of cases)”.
Sources for further information on national and international data:
Most Polluted Countries
WHO guidelines
