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For the convenience of our customers and interested citizens, in this section of the site we have collected key documents related to noise and vibrations.

For more information, do not hesitate to contact us!

About Noise

Environmental noise is any unwanted or harmful external sound caused by human activity, including the noise emitted by means of transport from road, rail, water and air transport, from industrial and local noise sources. Its unpleasant impact on the person causes stress over time and leads to diseases the human organism.

The Impact of Noise on Health and its Cost for Society
Noise has a diverse impact on human health and is officially recognized by the "World Health Organization" (WHO) as a factor with a serious impact on public health.

  • The most common effects are states of irritability, fatigue and impaired concentration caused by noise.
  • The harmful effects of noise are not evenly distributed among society - vulnerable groups such as children, the elderly, as well as people suffering from severe mental and physical disorders and diseases are affected to a higher degree.
  • There is undisputed evidence that road traffic noise leads to sleep disturbances, cognitive impairment (especially in adolescents), and cardiovascular disease.

People who are exposed during sleep to an average annual nighttime noise exposure of more than 40 dB(A), which corresponds to the sound exposure of a quiet and peaceful street, may suffer minor health effects such as sleep disturbances and insomnia. Above 55 dB(A) average long-term noise exposure, similar to the noise of a normal conversation, can lead to increased blood pressure and heart attacks.

One in five Europeans is regularly exposed to noise above 55 dB(A) at night.

High levels of noise act as a stress factor and attack almost all organs and systems of the human body. Loud noise affects the auditory organ, central and autonomic nervous system. People become restless, irritable, unable to work, often have headaches and dizziness, suffer from insomnia. Sharp sudden noises increase the secretion of adrenaline from the adrenal glands, which leads to constriction of blood vessels, disruption of peripheral circulation and an increase in blood pressure. All this contributes to the development of hypertension and atherosclerosis and can lead to severe vascular accidents - strokes, heart attacks, thrombosis, etc.

As a powerful stress factor, noise does not exhaust its harmful effects on the body only with the auditory function. It affects the neuro-psychic system, the cardiovascular system, the gastrointestinal tract, the endocrine glands, metabolism, the muscular apparatus, etc. Studies have shown that there is no organ in the human body that is spared the harmful effects of noise.

Harm from unwanted noise is highly pronounced on children. For them, noise can affect their ability to concentrate, read and write. In classes where there is a lot of noise, students show significantly lower results than those in another class and the same school, where the harm of noise is avoided. According to WHO data, at the community level, noise pollution leads to lower birth rates, impaired learning, increased accidents and increased drug abuse. And last but not least, it has been proven that long-term exposure to noise with values higher than 70 dB(A) can lead to irreversible hearing loss.

Indicators for Noise Levels and Limit Values

To protect people from the harmful effects of noise, limit values have been adopted for individual noise indicators.

Noise indicators and limit values in the Republic of Bulgaria are regulated by Regulation No. 6 of June 26, 2006 (attached below) issued by the Ministry of Health and the Ministry of Environment and Water.

Noise indicators are physical quantities by which noise in the environment is determined, taking into account the limits and the degree of discomfort of people exposed to noise, depending on the nature of the noise, the time of day, the purpose of the living spaces, the nature of the territories and zones in and outside the urbanized territories.

The main noise indicators are:

  • noise level during the day - Lday, which is an indicator of the noise associated with discomfort during the daytime time period (from 7:00 to 19:00);
  • noise level during the evening - Levening, which is an indicator of the noise associated with discomfort during the evening time period (from 19:00 to 23:00);
  • noise level during the night - Lnight, which is an indicator of the noise associated with discomfort during the nighttime period (from 23:00 to 7:00);
  • noise level during the day and night - L24, which is an indicator of noise related to discomfort throughout the day and is determined by a computational method from the values of Lday, Levening and Lnight.

The limit values of noise levels in the premises of residential buildings, buildings with mixed purpose and public buildings, including objects with public purpose are given in Table No. 1 of Appendix No. 2 to Art. 5 of Regulation No. 6/2006:

Purpose of the Premises Equivalent noise level Leq dB(A)
day evening night
1 Rooms and operating rooms in medical facilities 30 30 30
2 Living rooms, study rooms and bedrooms in the children's facilities, sleeping quarters in dormitories, accommodation rooms in accommodation facilities within the meaning of § 1, item 9, letter "в" of the additional provisions of the Health Act 35 35 30
3 Doctor's offices in medical institutions, rooms for conferences, auditoriums of theaters and cinemas 40 40 35
4 Classrooms and auditoriums in educational institutions, research institutions, training rooms in schools and centers for working with children, reading rooms 40 40 40
5 Work premises in administrative buildings 50 50 50
6 Dining halls in public catering establishments, lobbies of theaters and cinema halls, clubs, barber, hairdressing and beauty salons, studios for tattoos and piercing and other similar products on various parts of the body, medical SPA centers, spa centers, wellness centers and thalassotherapy centers and saunas 55 55 55
7 Commercial halls of shops, passenger halls in stations 60 60 60


  • When affected by tonal or impulse noise, the correction is -5 dB(A) and applies to premises from item №1 to item №5 of Тable 1.
  • Tonal noise is characterized by a sound with a certain frequency (tone) and is determined by measurement.
  • Impulse noise is noise that is perceived as separate beats and consists of one or several pulses of sound energy, the duration of each pulse being less than 1 s.

The limit values of noise levels in the various territories and development zones in the urbanized territories and outside them are given in Table No. 2 of Appendix No. 2 to Art. 5 of Regulation No. 6/2006:

Territories and development zones in the urbanized territories and outside of them Equivalent noise level Leq dB(A)
day evening night
1 Residential areas and territories 55 50 45
2 Mixed central city areas 60 55 50
3 Areas subject to heavy traffic 60 55 50
4 Areas affected by rail and tram transport 65 60 55
5 Areas affected by aircraft noise 65 65 55
6 Production and storage territories and zones 70 70 70
7 Areas for public and individual recreation 45 40 35
8 Areas for medical facilities 45 35 35
9 Areas for scientific research and educational activity 45 40 35
10 Quiet areas outside urban areas 40 35 35

Note: The limit value of the maximum noise level when flying an aircraft over a certain territory is 85 dB(A).

Selected Regulations in the Republic of Bulgaria Related to the Concept of Noise

Selected Laws in the Republic of Bulgaria Related to the Concept of Noise

Selected European and International Documents

Other Useful Infromation

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