Panel 1
Simona BUSCEMI, Giorgio CATTANI, Alessandra GAETA, Federica NOBILE (Department of Epidemiology of the Regional Health Service-Lazio Region ASL Rome 1), Maria Antonietta REATINI, Massimo STAFOGGIA (Department of Epidemiology of the Regional Health Service-Lazio Region ASL Rome 1)
Estimates of the average annual exposure weighted for the population were developed ( Population Weighted Exposure , PWE) to the PM 2.5 aggregated at municipal level, through the integrated use of statistical measures and models. The data obtained, relating to the period 2016-2024, allow the comparison of PWE between all municipalities and to have a complete picture of the average exposure at a national level.
In 2024, 100% of the population was exposed to levels above the WHO guideline value (5 µg/m 3). The national average of PWE was 12 µg/m 3 (minimum-maximum range: 4 – 24 µg/m 3).
In the period 2016-2024, the national average goes from 15 µg/m 3 of 2016 at 12 µg/m 3 of 2024, recording a reduction of 20%.
The most accredited health estimates attribute a significant portion of premature deaths and reductions in life expectancy linked to exposure to air pollutants (WHO, 2016; EEA, 2022, WHO, 2021).
The assessment of population exposure and related spatial and temporal variability outdoor represents a fundamental step for epidemiological studies that relate exposure to air pollution and health effects (Caplin et al., 2019).
The indicator provides an estimate of the average annual exposure weighted for the population ( Population Weighted Exposure , PWE) to PM2.5 aggregated at municipal level allowing the comparison of the situation between different cities and to have a complete picture of the average exposure at a national level. It is representative of the chronic exposure of the population and useful for estimates of long-term health effects.
The exposure values are compared with the reference values (guidelines e interim target ) indicated by the World Health Organization (WHO, 2021).
Estimate the average exposure of the population to the main airborne pollutants, evaluate the exposure levels for comparison with the WHO reference values and evaluate the trend of exposure over time.
Legislative Decree n. 155 of 13 August 2010 and subsequent amendments. In implementation of Directive 2008/50/EC and Directive 2004/107/EC.
WHO (2021), Global Air Quality Guidelines. Particulate matters (PM10, PM2.5), ozone, nitrogen dioxide, sulfur dioxide and carbon monoxide . Geneva, World Health Organization, 2021.
A “Clean Air” program for Europe. Brussels, 18.12.2013 COM (2013) 918 final.
A Europe that protects: clean air for all. Brussels, 17.5.2018 COM(2018) 330 final.
A path to a healthier planet for all EU Action Plan: “Towards zero pollution for air, water and soil”. Brussels, 12.5.2021 COM(2021) 400 final .
In the revision of the Guidelines, the WHO produced numerical risk estimates for a series of health effects associated with an increase of 10 µg/m³ in the average annual concentration of various pollutants. In its assessments, the WHO does not establish a value below which there is no risk, but identifies the value of 5 µg/m³ for PM2.5 as the lower limit of average annual exposure, called " Air quality guideline level " which can be translated as "reference level": it is the lowest level for which an increase in total mortality, mortality from cardiopulmonary causes, and mortality from lung cancer has been observed, with a confidence interval of 95%. The WHO has also defined " interim target ”, i. e. The highest reference levels to be considered as objectives to be achieved in step subsequent periods, through the implementation of air quality improvement policies. The i nterim target for PM2.5 proposed by the WHO they are equal to 10 µg/m³ (IT 4), 15 µg/m³ (IT 3), 25 µg/m³ (IT 2) and 35 µg/m³ (IT 1).
The EU's clean air programs have set the medium to long-term target to comply with WHO air quality guidelines, which are much stricter than the standards set by the EU air quality directives and are based on what is deemed necessary to ensure the protection of human health.
The Clean Air Policy Package and the Zero Pollution Action Plan aim to reduce the number of premature deaths linked to air pollution by more than half by 2030 at European level compared to 2005.
Panel 2
Caplin A., Ghandehari M., Lim C., Glimcher P., Thurston G.(2019), Advancing environmental exposure assessment science to benefit society. Nature communication (2019) 10:1236. Https://doi. org/10.1038/s41467-019-09155-4.
EEA (2022), Health Risk Assessment of Air Pollution and the Impact of the New WHO Guidelines . Eionet Report – ETC/ATNI 2022/10.
EUROSTAT (2022), Sustainable development in the European Union — Monitoring report on progress towards the SDGs in an EU context - 2022 edition. (DOI): 10.2785/313289.
Stafoggia M, Bellander T, Bucci S et al. Estimation of daily PM10 and PM2.5 concentrations in Italy, 2013-2015, using a spatiotemporal land-use random-forest model. Environ Int 2019;124:170-79.
Stafoggia M, Cattani G, Ancona C, Ranzi A. The assessment of the exposure of the Italian population to air pollution in the period 2016-2019 for the study of the relationship between air pollution and COVID-19. Epidemiol Prev. 2020 Sep-Dec;44(5-6 Suppl 2):161-168. Italian. Doi: 10.19191/EP20.5-6. S2.115. PMID: 33412807.
WHO (2016), Ambient air pollution: A global assessment of exposure and burden of disease. Geneva, World Health Organization , 2016.
WHO (2021), Global Air Quality Guidelines. Particulate matter (PM10, PM2.5 ), ozone, nitrogen dioxide, sulfur dioxide and carbon monoxide. Geneva , World Health Organization, 2021.
The population considered is that distributed in the 2021 permanent census sections, which represents the most recent territorial base available.
The indicator expresses an average exposure value of the population at municipal level. Within a single municipality it is known that there is variability in the concentration of pollutants with areas where the levels may be higher than the average or background values. However, the assessment of exposures on a local or microscale within individual municipalities goes beyond the scope of this indicator. However, it should be underlined that, within the municipality, the areas with higher population density are weighted more heavily in the PWE calculation.
In any case, the exposure values obtained should not be compared with the legal limit values: in this case, in fact, for the purpose of assessing compliance with the legal limits, it is necessary to use the highest value among those measured by the individual monitoring stations.
Application of high spatio-temporal resolution models, with the use of spatio-temporal predictors, satellite data, air quality monitoring data.
Data quality assessment
DEP: Department of Epidemiology of the SSR Lazio Region - ASL RME IS
ISTAT
SNPA (National System for Environmental Protection)
ISPRA - InfoARIA Database;
ISTAT - www. demo. istat. it
National, Regional, Municipal (7,901/7,914)
2016-2024
Indicator assessment
The model uses the average daily concentrations measured in monitoring stations distributed across the national territory as a response variable and a selection of spatial and temporal predictors as explanatory variables. The monitoring data is collected and archived in ISPRA in databases InfoAria, in accordance with the provisions of Directive 2008/50/EC (and the transposing Legislative Decree no. 155/2010) and Decision 2011/850/EU.
A model has been developed machine learning , The random forest , which relates the daily concentrations of monitoring stations with spatial (population density, road network, land cover, altitude, artificial surfaces, etc.) and spatio-temporal (dispersion models, meteorology) predictors in order to estimate average daily levels of PM2.5 for each km 2 of the Italian territory.
Starting from the daily concentrations estimated by the model random forest , the average annual exposure of the Italian population was calculated by weighting the concentrations of each pollutant at the single cell level for the population residing within the cell itself.
The "national average concentration value" is calculated as the weighted average of the concentrations estimated for each municipality, considered with weights proportional to the resident population.
Finally, the percentage distribution of the resident population exposed to different PM2.5 concentration bands is estimated.
In 2024, 100% of the population was exposed to levels above the WHO guideline value (5 µg/m 3); 83% were exposed to levels higher than the interim target IT 4 (10 µg/m 3); 33% of the population was exposed to levels higher than IT3 (15 µg/m 3). In the latter case, the exposed population is mainly concentrated in the Po Valley area, affecting Veneto, Lombardy, Emilia-Romagna and Piedmont - (Figure 1 and Table 1). In no municipality were PWE levels higher than IT2 (25 µg/m 3).
The national average of PWE was 12 µg/m 3 (4 – 24 µg/m 3, range minimum-maximum) (Figure 2).
In the nine years taken into consideration (2016-2024), there was an overall tendency for PWE values to decrease, with the sole exception of 2017, the year in which a higher average value was observed (16 µg/m 3) (Figure 2). The national average, in fact, goes from 15 µg/m 3 in 2016 at 12 µg/m 3 in 2024, recording a reduction of 20%. However, the period investigated is too short to be able to estimate a trend and its statistical significance, which is therefore not definable and appears evident, in most cases, when analyzing the data over a time horizon of 10 years or more.
From 2016 to 2024, 100% of the population continues to be exposed to a concentration of PM 2.5 above the WHO threshold value. However, there is a tendency towards a reduction in the share of the population exposed to levels higher than IT3 (15 µg/m 3), which goes from 52% to 33%. In all the years considered, PWE was never higher than IT1 (35 µg/m 3) and in 2024 the IT2 of 25 µg/m will also not be exceeded 3, confirming what has already happened in the previous six years 2018-2023 (Figure 3).
Data
Figure 1: Population-weighted average exposure to atmospheric particulate matter PM₂.₅ at the municipal level (2024).
ISPRA processing based on data from the Department of Epidemiology of the Lazio Regional Health Service.
Figure 2: Annual distribution of PWE values (population-weighted average exposure to atmospheric particulate matter PM₂.₅ at the municipal level).
ISPRA processing based on data from the Department of Epidemiology of the Lazio Regional Health Service.
The box:
represents the interquartile range, i.e. the difference between the third quartile (Q3, 75th percentile) and the first quartile (Q1, 25th percentile) of the data. The line inside the box indicates the median (Q2, 50th percentile), while the point represents the mean value.
Figure 3: Percentage of the population exposed to atmospheric particulate matter PM₂.₅ by exposure range and year.
ISPRA processing based on data from the Department of Epidemiology of the Lazio Regional Health Service.
c= PWE (µg/m3)
The six reported PWE classes correspond respectively to the WHO guideline value and the four WHO interim targets.
Table 1: PM₂.₅ – Population-weighted average exposure (PWE) by region: percentage distribution by exposure classes (2024).
ISPRA processing based on data from the Department of Epidemiology of the Lazio Regional Health Service.
PWE: population-weighted average exposure (Population Weighted Exposure).
The six reported PWE classes correspond respectively to the WHO guideline value and the four interim targets.
The indicator complies with those used on a European scale by the EEA and on a global scale by the World Health Organization to monitor exposure. It also represents the basis ( exposure assessment ) to prepare health risk assessments ( health risk assessment and burden of disease ) in a manner consistent with the approaches of the same two supranational organizations.
With reference to the United Nations sustainable development goals ( SDGs goals ), the methodological approach is consistent with that followed for the calculation of the indicator useful for monitoring progress relating to Goal 11 (make cities and human settlements inclusive, safe, durable and sustainable), target 11.6 (By 2030, reduce negative environmental impacts per capita of cities, in particular regarding air quality and waste management).
From a methodological point of view, the exposure estimate thus obtained also represents the basis for developing one of the indicators useful for monitoring progress relating to the Goal 3 (Ensure health and well-being for all at all ages), target 3.9 (By 2030, substantially reduce the number of deaths and illnesses from hazardous chemicals and from pollution and contamination of air, water and soil.)