Panel 1
Massimiliano BULTRINI, Simona BUSCEMI, Giorgio CATTANI, Alessandra GAETA, Federica NOBILE (Dipartimento di Epidemiologia del Servizio Sanitario Regionale-Regione Lazio ASL Roma 1), Maria Antonietta REATINI, Massimo STAFOGGIA (Dipartimento di Epidemiologia del Servizio Sanitario Regionale-Regione Lazio ASL Roma 1)
Estimates of annual population-weighted exposure (PWE) to PM10, aggregated at municipal level, were produced using an integrated approach combining measurements and statistical modelling. The resulting data, covering the period 2016–2023, allow for comparison of PWE across all municipalities and provide a comprehensive national overview of average exposure levels.
In 2023, 96% of the population was exposed to concentrations above the WHO air quality guideline (15 µg/m3).
In the period observed, no decreasing trend in exposure levels was detected. The national average in 2023 was 20 µg/m³ (minimum–maximum range: 6–35 µg/m³).
The most authoritative health estimates attribute a significant share of premature deaths and reduced life expectancy to exposure to air pollutants (WHO, 2016; EEA, 2022; WHO, 2021).
Assessing population exposure and its spatial and temporal variability in outdoor environments is a key step in epidemiological studies that investigate the relationship between air pollution and health effects (Caplin et al., 2019).
This indicator provides an estimate of the annual population-weighted exposure (PWE) to PM10, aggregated at the municipality level, enabling comparisons between cities and offering a comprehensive national overview of average exposure.
It is representative of chronic exposure and is useful for estimating long-term health impacts.
Exposure levels are compared with the reference values (guideline levels and interim targets) set by the World Health Organization (WHO, 2021).
Estimate the average population exposure to the main airborne pollutants, assess exposure levels against WHO reference values, and evaluate the temporal trends in population exposure.
Legislative Decree No. 155 of 13 August 2010, as amended, transposing Directive 2008/50/EC and Directive 2004/107/EC.
WHO (2021), Global Air Quality Guidelines. Particulate matter (PM10, PM2.5), ozone, nitrogen dioxide, sulfur dioxide and carbon monoxide. Geneva, World Health Organization, 2021.
A Clean Air Programme 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.
Pathway to a Healthy Planet for All – EU Action Plan: “Towards Zero Pollution for Air, Water and Soil”, Brussels, 12.5.2021, COM(2021) 400 final.
As part of the revision of its Air Quality Guidelines, the World Health Organization (WHO) has provided quantitative risk estimates for a range of health effects associated with an increase of 10 µg/m³ in the annual average concentration of various pollutants. In its assessments, the WHO does not establish a threshold value below which no risk occurs. However, it identifies 15 µg/m³ as the lower limit of annual mean exposure for PM₁₀, referred to as the Air Quality Guideline (AQG) level, which can be translated as the “reference level”. This represents the lowest concentration at which increases in total mortality, cardiopulmonary mortality, and lung cancer mortality have been observed, with a 95% confidence level.
The WHO has also defined a set of interim targets (ITs), i.e. higher reference levels to be considered as intermediate objectives to be progressively achieved through the implementation of air quality improvement policies. The interim targets for PM₁₀ proposed by the WHO are 20 µg/m³ (IT4), 30 µg/m³ (IT3), 50 µg/m³ (IT2) and 70 µg/m³ (IT1).
EU policy objectives for clean air aim to progressively align with WHO air quality guidelines, which are significantly stricter than current EU air quality standards and are based on levels deemed necessary to ensure effective protection of human health.
The EU Clean Air Policy Package and the Zero Pollution Action Plan set the objective of reducing the number of premature deaths attributable to air pollution by more than 50% by 2030, compared to 2005 levels.
Panel 2
Caplin A., Ghandehari M., Lim C., Glimcher P., Thurston G. 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, 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. (2019) 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. La valutazione dell’esposizione della popolazione italiana all’inquinamento atmosferico nel periodo 2016-2019 per lo studio della relazione tra inquinamento atmosferico e 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 the one distributed across the 2021 census sections, which represent the most recent territorial reference available.
The indicator expresses a municipality-level average of population exposure. It is well known that within a single municipality, there may be spatial variability in pollutant concentrations, with some areas experiencing higher levels than the municipal average or background concentrations. However, the assessment of local- or microscale-level exposure within individual municipalities falls outside the scope of this indicator.
It is important to note that areas with higher population density within a municipality are given greater weight in the calculation of the Population Weighted Exposure (PWE).
In any case, the exposure values obtained should not be compared with legal limit values: for the purpose of compliance assessment with legal thresholds, the highest value measured by individual air quality monitoring stations should be used instead.
Application of high-resolution spatiotemporal models, using spatiotemporal predictors, satellite data, and air quality monitoring data.
Data quality assessment
DEP: Dipartimento di Epidemiologia del SSR Regione Lazio - ASL RME ISPRA (Istituto Superiore per la Protezione e la Ricerca Ambientale)
ISTAT (Istituto Nazionale di Statistica)
SNPA (Sistema Nazionale per la protezione dell’ambiente)
ISPRA - Database InfoARIA
ISTAT - www.demo.istat.it
National, Regional and Municipal level (7,901 out of 7,914 municipalities)
2016-2023
Indicator assessment
The model uses daily average concentrations measured at air quality monitoring stations across the national territory as the response variable, and a selection of spatial and temporal predictors as explanatory variables. Monitoring data are collected and stored by ISPRA in the InfoAria database, in accordance with Directive 2008/50/EC (and its national transposition by Legislative Decree No. 155/2010) and Decision 2011/850/EU.
A machine learning model—random forest—was developed to relate daily pollutant concentrations from monitoring stations to spatial predictors (such as population density, road network, land cover, altitude, artificial surfaces, etc.) and spatiotemporal predictors (dispersion modelling, meteorological data), in order to estimate daily mean PM10 concentrations for each km² grid cell across the Italian territory.
Based on the daily concentration estimates from the random forest model, the annual population-weighted exposure to PM10 was calculated by weighting the concentration values in each grid cell by the population residing in that cell.
The “national average concentration value” is computed as the population-weighted mean of the estimated concentrations at the municipal level, using the resident population as weights.
Lastly, the percentage distribution of the resident population exposed to different PM10 concentration classes is estimated.
In 2023, 96% of the population was exposed to levels above the WHO guideline value (15 µg/m³); 69% was exposed to concentrations above Interim Target 4 (IT-4, 20 µg/m³); and 5% of the population, residing in 282 municipalities, was exposed to levels exceeding Interim Target 3 (IT-3, 30 µg/m³). In this latter case, the exposed population is mainly concentrated in the Po Valley area, particularly in Veneto and Lombardy (Figure 1 – Table 1).
In 2023, no municipality recorded Population Weighted Exposure (PWE) levels above Interim Target 2 (IT-2, 50 µg/m³).
The national average PWE was 20 µg/m³ (range: 6–35 µg/m³) (Figure 2).
Over the eight years considered, Population Weighted Exposure (PWE) values show an overall tendency to remain stable, with the sole exception of 2017, when a higher national average value (23 µg/m³) was observed (Figure 2). Although the trend has not been quantitatively assessed using statistical methods and refers to a relatively short period, it appears consistent with that observed over the last decade at air quality monitoring stations.
Between 2016 and 2023, the share of population exposed to PM₁₀ concentrations below the WHO guideline value ranged between 3% and 5%, reaching its minimum in 2022. At the same time, in all years considered, PWE never exceeded Interim Target 2 (IT-2, 50 µg/m³) (Figure 3).
Data
Figure 1: Population-Weighted Exposure to PM10 at Municipal Level (2023)
ISPRA processing based on data from the Epidemiology Department of the Lazio Regional Health Service
Figure 2: Annual distribution of Population-Weighted Exposure (PWE) to PM10 at Municipal Level
ISPRA processing based on data from the Epidemiology Department of the Lazio Regional Health Service
The box represents the interquartile range (IQR), which is 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 dot represents the mean value.
Figure 3: Percentage of population exposed to PM₁₀ by exposure range and year
ISPRA processing based on data from the Epidemiology Department of the Lazio Regional Health Service
The six PWE classes correspond respectively to the WHO air quality guideline value and the four interim targets.
Table 1: PM10 - Population-Weighted Exposure (PWE) by region: Percentage distribution by exposure range (2023)
ISPRA processing based on data from the Epidemiology Department of the Lazio Regional Health Service
PWE: Population Weighted Exposure
The six PWE classes correspond respectively to the WHO air quality guideline value and the four interim targets.
The indicator is aligned with those used at the European level by the European Environment Agency (EEA) and globally by the World Health Organization (WHO) to monitor population exposure.
Moreover, it serves as the basis for exposure assessment in the development of health risk assessments and burden of disease evaluations, in accordance with the methodologies adopted by both supranational organizations.
With reference to the United Nations Sustainable Development Goals (SDGs), the methodological approach is consistent with that used to calculate the indicator for monitoring progress towards Goal 11 ("Make cities and human settlements inclusive, safe, resilient and sustainable"), specifically Target 11.6 ("By 2030, reduce the adverse per capita environmental impact of cities, including by paying special attention to air quality and municipal and other waste management").
From a methodological standpoint, the exposure estimate also provides the foundation for one of the indicators used to monitor progress towards Goal 3 ("Ensure healthy lives and promote well-being for all at all ages"), specifically Target 3.9 ("By 2030, substantially reduce the number of deaths and illnesses from hazardous chemicals and air, water and soil pollution and contamination").