Panel 1
Giorgio Cattani, Mariacarmela Cusano, Alessandro Di Menno di Bucchianico, Raffaela Gaddi, Alessandra Gaeta, Giuseppe Gandolfo, Gianluca Leone
The indicator is based on atmospheric PM2.5 concentration data measured in 2023 at monitoring stations distributed across the national territory, collected and archived by ISPRA in the InfoAria database, in accordance with Directive 2008/50/EC (and its national transposition, Legislative Decree 155/2010, as amended) and Commission Implementing Decision 2011/850/EU.
A total of 334 monitoring stations measured and reported PM2.5 data. Of these, 310 provided data series with sufficient temporal coverage to assess compliance with reference values. The annual limit value for PM2.5 (25 µg/m³) was met at all stations except one, corresponding to 0.3% of cases. However, the majority of monitoring stations (99.7%) exceeded the updated WHO annual reference value of 5 µg/m³ (previously set at 10 µg/m³).
Airborne particulate matter refers to the mixture of solid and liquid particles suspended in ambient air. The term PM2.5 identifies particles with an aerodynamic diameter (d.a.) less than or equal to 2.5 µm.
Due to their small size, PM2.5 particles can penetrate deeply into the human respiratory system, bypassing the tracheobronchial barrier and reaching the alveolar region. PM2.5 is also referred to as “fine particulate matter,” in contrast to “coarse particulate matter,” which includes particles with a diameter greater than 2.5 µm or, within the PM10 fraction, those with diameters between 2.5 and 10 µm.
The direct emission of fine particulate matter is associated with all combustion processes, particularly those involving solid fuels (coal, wood) or petroleum distillates with a medium-to-high carbon chain length (diesel, fuel oil). Fine particles are thus emitted from internal combustion engine exhaust, energy production plants, industrial combustion processes, domestic heating systems, and wildfires.
The mass concentration of PM2.5 is dominated by accumulation-mode particles—those with diameters ranging from approximately 0.1 µm to 1 µm—which exhibit long atmospheric residence times. Secondary particulate matter, formed in the atmosphere from precursor gases or through aggregation of smaller particles and gas condensation on preexisting particles, can account for a substantial portion of the observed PM2.5 mass concentration.
The indicator was developed using PM2.5 concentration data measured in 2023 at monitoring stations across the national territory, collected and archived by ISPRA in the InfoAria database in accordance with Commission Implementing Decision 2011/850/EU. Parameters were calculated to enable comparison with the regulatory limit values for human health protection established by the reference legislation (Legislative Decree 155/2010, as amended) and with the WHO guideline values (WHO-AQG, 2021). The following metrics were calculated: mean, 5th, 25th, 50th, 75th, 90.4th, 95th, and 99th percentiles, as well as the maximum of daily average values.
To provide information on the state of air quality through statistical parameters calculated from ambient concentration data, verifying compliance with the regulatory limit values and comparing the results with the reference levels established by the World Health Organization (WHO).
2011/850/EU: Commission Implementing Decision of 12 December 2011 laying down provisions for the implementation of Directives 2004/107/EC and 2008/50/EC of the European Parliament and of the Council as regards the reciprocal exchange and reporting of information on ambient air quality.
The objective of Directive 2008/50/EC is to enable the assessment of air quality on a harmonized basis, to gather information on air quality status with the aim of combating atmospheric pollution, to ensure the public availability of information, and to promote cooperation among Member States.
Legislative Decree 155/2010, which transposes the directive at the national level, also aims to enable regions and autonomous provinces to assess and manage ambient air quality.
The limit values set out in Legislative Decree 155/2010 represent ambient air quality objectives to be pursued in order to avoid, prevent, and reduce harmful effects on human health and the environment as a whole.
The WHO reference values serve as guidance in reducing the health impact of air pollution.
The ambient air quality limit values for PM2.5 established by Legislative Decree 155/2010 are:
- For a calendar year averaging period: 25 µg/m³.
The WHO Global Air Quality Guidelines 2021 specify the following reference values for PM2.5 in ambient air:
- For long-term human exposure: 5 µg/m³ (annual mean);
- For short-term human exposure: 15 µg/m³, not to be exceeded more than three days per year.
Panel 2
ISPRA, Annuario dei dati ambientali, various editions
SNPA, 2024, La qualità dell'aria in Italia. Ed. 2023
WHO global air quality guidelines. Particulate matter (PM2.5 and PM10), ozone, nitrogen dioxide, sulfur dioxide and carbon monoxide. Geneva: World Health Organization; 2021.
Data quality assessment
Autonomous Provinces
Regions
SNPA (National System for Environmental Protection)
Database InfoAria - ISPRA
National
Regional: (20/20)
Provincial: (101/110)
Municipal: (248/8047)
2014-2023
Indicator assessment
The indicator is based on PM2.5 concentration data measured at monitoring stations distributed across the national territory, collected and archived by ISPRA in the InfoAria database in accordance with Commission Implementing Decision 2011/850/EU. Parameters were calculated for comparison with the limit values for human health protection established by the reference legislation (Legislative Decree 155/2010) and with the reference levels set by the WHO for the protection of human health. All parameters were computed following European standards and were verified by the Regions, Autonomous Provinces, and environmental protection agencies (ARPA/APPA).
For comparison with the annual limit value established by Legislative Decree 155/2010 and the WHO reference level (as shown in Figure 2), only data series with a minimum temporal coverage of 90% (excluding gaps due to routine calibration or maintenance) were used.
The statistical trend analysis for the period 2014–2023 was conducted using the Mann-Kendall method corrected for seasonality. Implementing a deseasonalization procedure minimizes the effect of interannual variability due to deviations from the mean seasonal cycle, allowing for the identification of underlying trends and quantification of their statistical significance.
The annual limit value for PM2.5 (25 µg/m³) was met at all monitoring stations except one, corresponding to 0.3% of the cases. However, the WHO annual reference value was met at only one station in the monitoring network, with 99.7% of stations exceeding the threshold (Figure 2).
For PM2.5, a statistically significant decreasing trend was observed in 73% of cases (159 monitoring stations out of 219), with an estimated average annual variation of -0.5 µg/m³ per year [-2.7 µg/m³y to -0.1 µg/m³y]. Among the subset of stations with a statistically significant downward trend, the mean annual reduction was 3.0% [-15.9% to -0.9%] (Table 3, Figures 3 and 4).
Data
Figura 1: PM2,5 - Classificazione dei punti di campionamento secondi i criteri di ubicazione su macroscala (Allegato III, D.Lgs. 155/2010) (2023))
Elaborazione ISPRA su dati SNPA
Figura 2: PM2,5 - Stazioni di monitoraggio e superamenti del valore limite annuale per la protezione della salute (2023)
Elaborazione ISPRA su dati SNPA
Figura 3: PM2,5 - Distribuzione sul territorio delle stazioni analizzate e variazione percentuale media annua stimata della concentrazione
Elaborazione ISPRA su dati SNPA
Risultati dell’analisi del trend con il test di Kendall corretto per la stagionalità su un campione di 219 stazioni (2014 - 2023).
Figura 4: PM2,5 - Distribuzione percentuale delle stazioni di monitoraggio in base all’andamento del trend osservato nel periodo 2014-2023
Elaborazione ISPRA su dati SNPA
p≤ 0,05: il trend osservato è statisticamente significativo p>0,05: non può essere esclusa l'ipotesi nulla (assenza di trend)
Sintesi dei risultati dell’analisi del trend (2014 - 2023) con il test di Kendall corretto per la stagionalità delle concentrazioni di PM2,5 in Italia su una selezione di 219 stazioni di monitoraggio distribuite sul territorio nazionale.
Tabella 1 - PM2,5. Stazioni di monitoraggio: dati e parametri statistici per la valutazione della qualità dell'aria (2023).
Elaborazione ISPRA su dati SNPA
“1” tipo di zona: U = Urbana; S = Suburbana; R = Rurale
“2” tipo di stazione: T = Traffico; F = Fondo; I = Industriale
"3" in grassetto i dati riportati in mappa. Valore evidenziato in grassetto soltanto per serie di dati con almeno il 90% di dati validi al netto delle perdite dovute alla taratura periodica o alla manutenzione ordinaria (in accordo ai criteri di qualità definiti nella normativa vigente, D.Lgs.155/2010)
“-” valore non calcolato per mancanza di dati
Tabella 2 - PM2.5. Classificazione delle zone rispetto alle soglie di valutazione e verifica della presenza di superamenti del valore limite annuale ai sensi del D.Lgs.155/2010 (2023)
Elaborazione ISPRA su SNPA
zona: parte del territorio nazionale delimitata, ai sensi del D.Lgs 155/2010, ai fini della valutazione e della gestione della qualità dell'aria ambiente;
agglomerato: zona costituita da un'area urbana o da un insieme di aree urbane che distano tra loro non più di qualche chilometro oppure da un'area urbana principale e dall'insieme delle aree urbane minori che dipendono da quella principale sul piano demografico, dei servizi e dei flussi di persone e merci, avente: 1) una popolazione superiore a 250.000 abitanti oppure; 2) una popolazione inferiore a 250.000 abitanti e una densità di popolazione per km 2 superiore a 3.000 abitanti;
Superamento VL annuale: Si intende superato qualora sia stato determinato il superamento in almeno una stazione di monitoraggio collocata nel territorio della zona.
Classificazione: aboveUAT: superiore alla soglia di valutazione superiore (70% del valore limite,17 μg/m³) LAT-UAT : compresa tra la soglia di valutazione inferiore e la soglia di valutazione superiore belowLAT : inferiore alla soglia di valutazione inferiore (50% del valore limite, 12 μg/m³) nota: Il superamento delle soglie di valutazione superiore e delle soglie di valutazione inferiore deve essere determinato in base alle concentrazioni degli inquinanti nell'aria ambiente nei cinque anni civili precedenti. Il superamento si realizza se la soglia di valutazione è stata superata in almeno tre sui cinque anni civili precedenti.
(a) Valutazione del superamento ottenuta mediante modello
Tabella 3 – PM2,5. Analisi dei trend per stazione di monitoraggio (2014-2023)
Elaborazione ISPRA su dati SNPA
p≤ 0,05: il trend osservato è statisticamente significativo
p>0,05: non può essere esclusa l'ipotesi nulla (assenza di trend)
Δy: variazione media annuale stimata sulla base dei risultati del test di Kendall corretto per la stagionalità
A total of 334 monitoring stations measured and reported PM2.5 data. Of these, 310 stations (92.8% of the total) met the minimum temporal coverage requirement of 90% (excluding data losses due to routine calibration or maintenance) (Table 1). All regions are represented. The classification of PM2.5 monitoring stations according to the macroscale siting criteria defined by legislation is shown in Figure 1.
The annual limit value (25 µg/m³) was exceeded at one station, corresponding to 0.3% of cases. The WHO annual reference value (5 µg/m³) was exceeded at 309 out of 310 stations (99.7% of cases) (Figure 2).
Exceedances of the annual limit value occurred in one zone out of 82, located in the Campania region (see Table 2).