This article presents a novel tool to quantify potential air quality co-benefits of local climate action and an analysis applying it to a large sample of cities across European and neighbouring countries. The tool estimates the effects of local actions tackling greenhouse gas (GHG) emissions associated with two sectors, namely residential buildings and transport, on air quality. It estimates emission changes associated with GHG mitigation actions described in city climate action plans (CAPs) for five key air pollutants, namely fine particulate matter (PM 2.5 ), nitrogen oxides (NOx), sulphur dioxide (SO 2 ), ammonia (NH 3 ) and volatile organic compounds (VOC). The analysis applies the tool to evaluate potential impacts of local climate action for 494 cities on ambient air pollutant emissions, based on 531 CAPs submitted to the Covenant of Mayors for Climate and Energy (CoM) initiative. The results demonstrate that GHG mitigation actions are often synergic with air pollution control strategies, offering significant air quality co-benefits. The magnitude and type of benefits depend on the sector and pollutant considered. Nevertheless, some actions may pose risks for air quality. There are risks of increasing, for example, ammonia emissions through a transport fuel switch and, more significantly, fine particulate matter emissions if solid biomass for heating in the residential sector is promoted. Therefore, context-specific data and case-by-case tailored analyses are needed to support the adequate integration of GHG mitigation and air quality policies at city level, avoiding potential trade-offs and maximizing synergies.
Monforti-Ferrario et al. (2026) studied this question.