The overall objective of the project is to improve ambient air quality in the municipality of Plovdiv by reducing the excessive levels of fine particulate matter (PM10). The specific objective of the project is to implement measures for the phased replacement of old and inefficient combustion plants and solid fuel units (wood and coal) for domestic heating as the main source of pollution identified in the municipal AAQ programme with new and upgraded ones. The project will be implemented in two phases. The first phase covers technical assistance for the preparation of investment measures and will be completed no later than 31.05.2021. In the first phase, the following activities will be carried out: survey of the attitudes of the population; organising and conducting an awareness campaign for the population; developing a comprehensive vision of the approach to replace solid fuel heating devices; preparation of a mechanism through which the applicant will ensure that investments in renovated buildings are prioritised; preparation of a mechanism that takes into account the revenue generated by the delivery of the replaced heating devices; preparation of procurement documents for the selection of a contractor; preparation of analyses, assessments, justifications and studies for the purpose of preparing the project proposal; development of average/limited prices per unit of product (replacement with pellet installation, gasification, etc.) or for heating per cubic meter for different alternative forms of heating when replacing a device of wood and coal.In the second stage, investment measures will be implemented for dismantling and replacement of stationary individual and multi-family solid fuel fuel units with heating devices using as fuel: pellets, woody biomass, fossil solid fuel, gas or electricity, and other alternative heat sources. Both phases will ensure project organisation and management as well as information and communication measures.