Sofia

Sofia, Bulgaria’s capital and largest city, is home to more than 1.4 million people. Set in the Sofia Valley beneath Vitosha Mountain, the city combines rich history with a growing role as a modern hub for culture and business. Learn how the city is working with Breathe Cities to ensure its residents breathe cleaner air. 

80% of Sofia’s winter air pollution comes from residential heating using coal and wood.

Air pollution in Sofia

Sofia’s residents live with air pollution levels that regularly exceed international guidelines. Although it now falls in the EU regulations, in 2023, the average concentration of fine particles (PM2.5) in the city’s air was around three times higher than the limit recommended by the World Health Organisation.

The largest source of this pollution is residential heating. Nearly three-quarters of harmful particles in Sofia’s air come from burning coal and wood, and in winter this rises to about 80% as some households still rely on solid fuels to heat their homes. Transport and in-born pollution also contribute to the problem, particularly through traffic emissions and pollution from nearby cities and regions, which together further worsen air quality across the city.

Poor air quality has a direct impact on Sofia’s economy and public health. It reduces productivity, drives up absenteeism, and makes it harder for the city to retain highly skilled workers. In 2019, air pollution was estimated to have cost the city 13.4% of its GDP through reduced labour output and lost working hours.

What we're doing in Sofia

Breathe Sofia is supporting the municipality to cut air pollution in half by 2030. A central focus is the city’s Low Emission Zones (LEZs) for transport and heating, the first of its kind in South-East Europe. The transport zone began in 2023 and is being expanded in phases, while restrictions on coal and wood heating start in 2025 and will extend across all districts by 2029. Breathe Sofia is working to ensure these measures are enforced effectively and operate throughout the year.

To track progress and strengthen policy, Breathe Sofia is measuring pollution inside the transport zone, expanding the city’s sensor network, and supporting the development of a robust air quality data platform. These steps are providing a stronger evidence base for decision-making and giving residents clearer information about the air they breathe.

Breathe Sofia is also providing technical support to phase out coal and wood heating and replace them with cleaner alternatives. This work includes sharing international best practice, analysing the costs of heating replacement to increase uptake, and addressing energy poverty so that vulnerable households, including Roma communities, are able to benefit from the transition.

Community engagement is a vital part of this approach. Breathe Sofia is raising awareness of the health impacts of air pollution, working with health professionals to highlight risks and benefits, and supporting residents in neighbourhoods where exposure is particularly high. By combining stronger data, effective policies, and public engagement, Sofia is making important progress towards cleaner, healthier air.

In Sofia, we work with a range of local partners and community groups in our efforts to clean the city’s air, including Air4Health, Za Zemiata, the Centre for Study of Democracy, EnEffect, Janev & Janev, AirBG, Chaordika and Trust for Social Achievement Foundation.