Statistical Modeling of the Early-Stage Impact of a New Traffic Policy in Milan, Italy.

Paolo Maranzano,Matteo Pelagatti,Alessandro Fassò,And Manfred Mudelsee

doi:10.3390/ijerph17031088

Abstract

Most urban areas of the Po basin in the North of Italy are persistently affected by poor air quality and difficulty in disposing of airborne pollutants. In this context, the municipality of Milan started a multi-year progressive policy based on an extended limited traffic zone (Area B). Starting on 25 February 2019, the first phase partially restricted the circulation of some classes of highly polluting vehicles on the territory, in particular, Euro 0 petrol vehicles and Euro 0 to 3 diesel vehicles, excluding public transport. This is the early-stage of a long term policy that will restrict access to an increasing number of vehicles. The goal of this paper is to evaluate the early-stage impact of this policy on two specific vehicle-generated pollutants: total nitrogen oxides (NO) and nitrogen dioxide (NO), which are gathered by Lombardy Regional Agency for Environmental Protection (ARPA Lombardia). We use a statistical model for time series intervention analysis based on unobservable components. We use data from 2014 to 2018 for pre-policy model selection and the relatively short period up to September 2019 for early-stage policy assessment. We include weather conditions, socio-economic factors, and a counter-factual, given by the concentration of the same pollutant in other important neighbouring cities. Although the average concentrations reduced after the policy introduction, this paper argues that this could be due to other factors. Considering that the short time window may be not long enough for social adaptation to the new rules, our model does not provide statistical evidence of a positive policy effect for NO and NO. Instead, in one of the most central monitoring stations, a significant negative impact is found.

Highlights

Air quality monitoring is one of the major challenges that European institutions jointly with national and local administrations are facing in terms of environmental protection
As already stated in the Introduction, we focus our attention on concentrations of total nitrogen oxides (NOx ) and nitrogen dioxide (NO2 ), which are mainly primary gaseous pollutants, considered as proxies of pollution emissions due to human activities, first of all car traffic
We considered seven important urban centres located in the Lombardy Po Valley area, which show socio-demographic and economic characteristics and weather conditions similar to Milan, but which cannot be directly affected by the limited traffic zone

Summary

Introduction

Air quality monitoring is one of the major challenges that European institutions jointly with national and local administrations are facing in terms of environmental protection. The 2008 European Air Quality Directive (AQD) 2008/50/EC [1] requires EU Member States to design appropriate air quality plans for zones where the air quality does not comply with the AQD limit values. In the last few decades, European countries implemented various modeling methods to assess the effects of local and regional emission abatement policy options on air quality and human health [2]. They include scenario approaches, in which running a chemical-physical simulation model with and without a specific emission source allows for quantifying the impact on air quality. Res. Public Health 2020, 17, 1088; doi:10.3390/ijerph17031088 www.mdpi.com/journal/ijerph

Objectives

Methods

Results

Conclusion