The scale of the problem
Nearly 97% of the population in the five largest Bulgarian cities – Sofia, Plovdiv, Varna, Burgas, and Ruse – live under conditions of long-term exposure to transport noise above 55 decibels. This covers over two million people, according to the results of the scientific study "Traffic noise assessment in urban Bulgaria using explainable machine learning," published in 2025 in the international journal "Sustainable Cities and Society."
The authors of the study – Marko Helbig, Julian Hagenauer, Angel Burov, and Angel Djambov – use data from 232 permanent monitoring points and machine learning technologies to create detailed noise maps with a grid of 50-meter cells.
Regional differences in decibels
The study shows significant differences in average noise levels between cities. Plovdiv recorded the highest values with an average of 68.36 decibels. Following are Ruse (65.45 dB), Burgas (64.81 dB), Sofia (61.53 dB), and Varna (57.06 dB).
In all investigated settlements, central areas are noisier than peripheral ones, with the highest levels observed around major road arteries, commercial, and industrial zones. For the five cities combined, 81.8% of residents (about 1.73 million people) fall into zones with prolonged high noise levels, with over half a million people exposed to levels of at least 65 decibels.
In Plovdiv, the share of people in such zones is the highest at 58.3%, while in Burgas it is 48%. Although the percentage in Sofia is lower (16.7%), due to the large number of residents, this means that nearly 195,000 people live in areas with high noise load.
Health and economic consequences
The World Health Organization (WHO) classifies environmental noise as a public health problem. According to the organization's recommendations for Europe, average exposure to noise from road traffic should be below 53 decibels (according to the Lden indicator).
Another study, published in 2025 in the journal "Environmental Research" by Angel Djambov and co-authors, examines the perception of 4,640 residents. It was found that for road traffic, strong irritation increases markedly above 62.5 decibels, while for railway and aviation noise, a similar reaction is observed at lower values – between 40 and 45 decibels.
You may also like
- 35 drivers were driving under the influence of alcohol and drugs in the last 24 hours
- Foxes in the Urban Environment: Animals Spotted in Various Parts of Sofia
- Police checks in Sliven region: confiscated licenses and sanctions for technical malfunctions
- Tragedy on the Ruse-Byala road: 4 dead after collision between truck and minibus; prosecution takes over investigation
The theoretical economic assessment of the consequences of noise on society is estimated at approximately 302 million euros. Researchers emphasize that solving the problem requires complex measures: improving pavement quality, traffic optimization, speed management, and better organization of urban space, rather than just the use of quieter vehicles.