Pedro Alcântra de Souza Alvares
In charge by Laboratory of Acoustic, CETEC/MG, 1979-1989
Technician of Brandt - Meio Ambiente-
Actually in Vitek Office - Belo Horizonte
Fernando Pimentel-Souza
Full Professor of Neurophysiology - UFMG,
Individual Member of the IBRO -UNESCO , PARIS
Electronics MS, ENSA-PARIS, ITA Engineer, Brazil
C.P. 486 - ICB - UFMG - 30.161-970 - Belo Horizonte
Tel.:(031) 499.29.39 - Fax: (031) 499.24.29


SUMMARY: In 1988 the urban noise, external and indoors in schools, and in 1991 in one hospital and in one home trangressed the city law 4034/85, edict 5893/88, ABNT recommendations and auditive wellbeing, giving noise stress in majority of people. Explosions from surrounding ore mining banged noxiously in some dwelling region. Internal levels in a home, from a lesser noisy region than mean, were showed also noxious. Claims increase in Militar Police and Ambiental City Secretary surveys. Similar noise pollution is probably occurring in many towns in Brazil. Peoples suffer and wait urgently from authorities and polititians actions and laws more effective to guard at least their remaining healths, to stop the worse.




Figure 1: Average noise level in each area of Belo Horizonte, where zc, comercial area, 
zr, residential area, and zi, industrial area and Leq, an average of the noise pression 
levels (WHO, 1980[1]). 


The average level of Leq of all the urban zones of BH city was 69,5 dB (A) (Figure 1). The zone ZI (industrial) had an Leq=66,7 dB (A), during the day, surprisingly almost 3 dB (A) less than the average, maybe cause in implantation phase and not well used. Been a place, where pertubation is almost null to citizens, because residents there wouldn't stay, it would be an ideal area to place the noisier activities, just as they do in the first world country cities and Curitiba. The average of the 8 tradicional residential zone, foreseen in the original director plan of Reis, in which incorporated a couple more of zones of the south district, considerated "nobles", had an Leq of 66,7 dB(A), exactly the same as ZI, showing a big indefinition about the actual planning of the city. The ZR5, including traditional noble residential districts of the mid-south such as Savassi, Funcionários, Lourdes and S Agostinho, had an Leq 71,7 dB(A), therefore 2 dB(A) above the average. Between the exclusively residential zones ZR1, including noble districts of the north area, next to Pampulha lake, added to BH about 50 years ago, showed in absolute better situation with a level of 61,0 dB(A)(Leq), during the day, so 8,5 dB(A) less than the average. The 6 comercial zones including the districts of Renascença, Floresta, S Inês, Cruzeiro, Grajaú, Pe Eustáquio, S Branca, S Amélia, Venda Nova and Pampulha Airport, and parts of Savassi, Funcionários, S Lucas, and not to say about downtown itself, they showed an average Leq of 73,8 dB(A) so more than 4 dB(A) above the average. However, even classified as comercials, a lot of these districts are typically residential and deserved better protection. The 21 serious areas of the city showed an Leq igual or superior to 79 dB(A) (Alvares and Pimentel-Souza, 1992[2]).

The noise of motor vehicles traffic is what contribuites more to the noise pollution. The Traffic Engineering can foresee the noise level in free spreading in function of the cars flow, that don't stop to grow numericaly in the cities, tending to aggravate the situation (CERNE, 1979[3]). It's expectable around 78 dB(A) to 15 m, when there is a flow of 1000 vehicles/hour with cars so noisy just like Brazilian ones. The noise level tend toget the same, when the traffic equals, when comparing streets with a lot of traffic in S Paulo, Rio or BH. Other big Brazilian Cities such as Salvador, Recife, Porto Alegre etc, and even echological urbanized Curitiba still has at least 4 points with more than 90 dB (Santana, 1991[4]), tend too reproduce areas in that the noise levels are equal to the 3 major capitals critic points. In these capitals that are unprovided arteries, surrounded with a very thick and high architectonic wall, trembling with motor vehicles surpassing and unknowingly people of the malefaction. Azevedo (1984[5]) foreseed a worsening of 2 dB(A) per years in Rio. In the accidental topography of BH aggravates the traffic noise, but still Rio and S Paulo continue more agglomerated, arresting the noise and having a more dense traffic.

On the other hand, the Traffic Noise Index (TNI, Griffiths & Langdon, 1968[6]) was calculated. According to his criators, the TNI has to do with midle values (L50), such as L90 and L10 and it's the more adequate to the subjective evaluation of annoyance. Some residents of ZR1, even though are living with the values lower of average noise (Leq), have potenciality of been more annoyed with the noise variation, since it's value TNI is the second higher one, 108 dB(A). Also it should be included the areas affected by the Pampulha Airport aircourse, where these accidental noises stay out of current evaluations. However, the areas ZR3, ZR4, ZR4A, ZR4B, ZR5, and ZR6, that has an higher Leq, has an lower TNI, around 95 dB(A), owing to a permanently traffic more intense, having values of L90 and L10 more close. However there is a bigger "adaptation" to noise, but without avoiding its slow health damage (Pimentel-Souza, 1992[7]).

To reduce disturbance, according to previsions using the TNI, it's not enough to limit the absolute average value of Leq, but to reduce also the oscilation between the L90 and L10 values. Paradoxaly, the noise in small towns of Brazil, as the average noise in the background lowers, it may annoy more than in the bigger cities, due to equipments and vehicles, originally coming from the same factories, that establish same potencial station source. In order for the get better of noise pollution at an minimum of 5 dB(A) in average the whole city should punish the violers of used cars and motorbikes, conductors and vandals extremely noisy, bohemian activities and semi-industrial activities in the residential zone and make all buses soundless (CERNE, 1979[3]). At mean time it should win 10 dB(A) adopting European rules or Australian rules for the motor vehicles fabrication or lose them if we don't take any severe rules towards the urbanism and architecture. Our streets are turning into accoustic boxes and our building excelent sources and means of noise transmitters (IPT, 1988[8]; Gerges, 1991[9]; Silva, 1991[10]). For this, is necessary to adopt plans to an direct urban growing plan and to use and occupate the ground for the big cities, in all these aspects. It is unbelievable how in Brazil it is not undestandable that is more racional, cheap and healthy to descentralize, build and support the development of small cities than to destroy and bad repair the unplodded center of the big cities, sometimes with historic loss.

The City of BH today can't be confused with the decanted one of the 40s and 50s, well deserveded called the "Garden City", with its restrained 400 thousand residents, that lived on the squares and streets with an auditable confort of 20 to 30 decibels. You could hear nature, make your own therapy of good sleep, dedicate to an intellectual activity and to develop reflection. At that time there was a maximum level of 70 dB, against 107 in the districts next to detonation of mines today. There's a difference of 37 dB that complete an increase of more than 4000 times of noise pression and something simular to the number of vehicles to an increase of 5 times of the population only (Nava, 1958[11]). The recovery policy of life quality will only be effective if it was deep, without losing its in superficialities, facing the mistakes of the new reality and recuing the possible, once life is unmaginable easily degradating.



The Municipal Environment Law, that have the control of the noise pollution in BH, is the number 4034/85, edict 5893/88, that establish among other things, maximum levels of internal noise for each of the 3 periods: Day (from 7AM to 7PM), evening (7PM to 10PM), and night (10PM to 7AM), according to the ground use and occupation law.

The internal readings accomplished in the library showed and Leq varying from 53,4 to 68,2 dB(A) and in the auditorium, Leq between 51,1 and 66,5 dB(A). Only when ambiental noise would get near of the minimum noise level was obeyed the Municipal Environment Law, which in this case prescribe to schools egual values to ZR1. A few times the noise level allowed audictible confort, 50 dB(A), to its user and almost was well above the beginning of stress, already in a forwarded stage (Cantrell, 1974[12]; WHO, 1980[1]; Babisch, 1991[13]). In the interior of the library in the School of Engineering and of the auditorium of the Music School the noise level would go over to 80 dB(A) (Lmax), showing as unsuitable places for reflection, for studies, for research, for intellectual criation and for the sensorial perception as it is prescribed, such as the rest of the other schools.

So the conclusion we reach is that the noise level at these schools is critical, since they don't follow the Ambiental Law, that does not even garantee healthy conditions (Pimentel-Souza, 1992[7]), moving away a lot of the recommended values by ABTN (1987[14]). The traffic is the principal infrator, allied to permissitivity of ambiental organs and the ecological absence of planning.



The internal readings accomplished in 1991 in the Medical Practice Hospital, during the hours of 9AM and 11AM, out of the traffic peak, showed Leq varying from 63,2 to 68,4 dB(A) (Table 1). In the Intensive Treatment Center (ITCs) the noise, although less, only for some moments would follow the Ambiental Law. The noise in hospitals is prescribed equal to ZR1, by notecing the minimum noise values (Lmin). At any moment the audictable confort would be proportioned, levels below 50 dB(A), to its future traumatic or life risk patients. On the contrary, they would stay almost always in an advanced noise stress condition.

TABLE 1-Levels of noise in dB(A), measured in the new interior part of the Medical Practice 
Hospital of UFMG, when it was not occupied by pacients. 



Leq(30 min)

(8th floor, extremity of block)




(8th floor, middle of block)




(8th floor, center of block)




(4th floor)




(2nd floor, extremity of block)




(2nd floor, center of block)





The noise in this hospital will continue still more critic inclusive in the new part. It doesn't follow the Ambiental Law, moving away a lot of the recommended values by ABTN (1987[14]), that is of 35 to 45 dB(A) for these places. Thanks to some traffic detour from the neighbourhood, these areas still concentrate about 20% of the buses traffic and the noise level stabilized around 73 dB(A) in the place Hugo Werneck in last years. Paradoxally the traffic there might come to grow to 50.000 vehicules/day, after the opening to traffic of an extensive viaduct. Certainly the report of the ambiental impact should not have seen such aspect or if it had it should not be considered.

The noise level is increasing in higher floors the buildings in the new block and extreme parts near the traffic track. It would be expectable the contrary considering the major distancing from the main station source, the local traffic. The noise from the Andradas avenue, located at some hundred meters in the north with an flow of some thousands vehicles per hour, is intercepted on the lower floors by the topography and other low constructions. Also the ITCs floors are better isolated from the exterior. The isolations and accoustic curtains could be more efficient projected, if they were projected according to the technical of accoustic control (CERNE, 1979[5]; Silva, 1991[12]). It is clear the indecision in the urbanization planning of the city about the destination of this central and important area between hospitalar and residential zones or traffic circulation.




Figure 2: Maximum noise levels in an apartment in the south zone of Belo Horizonte. The 
vertical bars indicate instantaneous noise as the motor vehicles went by, the higher ones 
referee to the buses and heavy weigh trucks, the middle ones, noisy cars, and the low 
ones, the less noisiest cars. Thick bars: with an arrow, horns or cars noise or motobike 
with adulterate exhaust, and with full circles with thin vertical bars, intermittent playing of 
balls on the superior floor. The traffic flow was estimated in 30 car/hour (5PM), 60 
(6PM), 30 (7PM), 15 (8PM) and 7 (10PM). 


Until 7PM the traffic noise reflected a lot in the residency interior, showing a strong oscilation between 55-81 dB(A) according with a flow of cars (Figure 2, D). From there on, in the evening and in the beginning of the night, the level would go up from the background noise (40 dB(A) at 11PM), in function of the drop of frequency of traffic, but maintaining on those two limits, cause the station source was the same. This means an ciclic oscilation on Leq decreasing and increase of TNI. Observe that in a case it reached 95 dB(A) from a passage of a car with open exhaust. This relation sign/background noise is more than sufficient to wake up the majority of people with deep sleep, which threshold in stages IV and paradoxal, in which one dreams, are from 35 and 31 dB(A) respectively (Lukas, 1971[15]). The internal noise, during the evening and beginning of night, were infringing the Environment Law, because its limit drops respectivily from 5 to 10 dB(A), annoying a lot more because of the background noise drop, transpassing the healthy limits (Cantrell, 1974[12]; WHO, 1980[1]; Babisch, 1991[13]; Pimentel-Souza, 1992[7]) and moving away considerably of recommended values by ABTN (1987[14]), which are between 35 and 45 dB(A).



The noise perturbation constitutes in the major complaints at SMMA (53% of the total) and Military Police (PM), the citizen is basing on the Municipal Law 4034/85, edict 5893/88 and article 42 of the penal code. The absolute excessive level of noise is prejudicial, but the variation of the background noise sometimes bothers more (Griffith & Langdon, 1968[6]). The complaints in BH increased so much that call the PM (phone 190) become almost useless (Alvares and Pimentel-Souza, 1992[2]). In mid 1991 the Military Police received more than 25 calls per day average, only attend to a few, when they sum up to plough an act of incident to posterior act of the SMMA. After the SMMA can assign a inspector to measure the pertubation, the majority doesn't exist no more. But it was catched in the act, it can have a fine or even retire the commerce authorization. The major judiciary law suits don't even begin. The straigh complaints to SMMA were low because it concentrates at the day time of work days and it was unknown its way of action. But, recent data seem to indicate an increase on the complaints at SMMA, more than 10 per day, as the people know that is more effective than PM. Damages to health and to work are not sued by the Procuracy and it's severity is underestimate by the judges, because they are not well informed, just as the own physicians, because they are new cientifically and still not well known. The unsatisfactory work accomplished until now putrify the instituitions images and envolved profissional categories. But, the PM is the only organ that maintain regular duty to restrain the noise pollution at times of trouble rest, at night and weekends, when most transgression happen. Recently the SMMA accepted the suggestion of one of the authors to work together with the PM during weekend nigths to measure of noise pression.

The registered complaints at SMMA can be distribute according to the station source, notecing the predominance perturbation of bars, restaurants and live music places, that astonishingly obtained at the Municipal Office approval to fix them in any district, and of semi-industrial activities, placed on residential areas. These are things that use to happens in a third world country!

By the noise disturbation in BH the perturbation due only to traffic the TNI should be provoking annoyance in about 100% ofthe population according to the Ollerhead (1973[16]) estimatives and would reach a " High " disturbance in about 50% of the population according to Schultz et al (1976[17]). So the reason to the level of complaints at the SMMA and PM, although increasing, still are underestimate and don't indicate the true level of disturbance and damages caused to the population.


BIBLIOGRAPHY: 1. WHO (1980). Noise. WHO, Geneve, 103p. 2. Alvares & Pimentel-Souza (1992). Rev. Acústica e Vibrações, 10:23-42. 3. CERNE (Eds.) (1979). Bruit dû aux moyens de transports. CERNE, BRON, 61p. 4. Santana (1991). "Folha de Londrina", 27 julho. 5. Azevedo (1984). Avaliação e controle do ruído industrial. CNI, Rio 6. Griffiths & Langdon (1968). J. Sound vib., 8(1), 16-32. 7. Pimentel-Souza (1992). Rev. Acústica e Vibrações, 10:12-22. 8 IPT (Ed.) (1988). Tecnologia de Edificações. PINI, SP. 415-460 p. 9. Gerges (1991). Tecnologia de minimização e medição da poluição sonora no meio urbano. Sem "Silêncio e Saúde". SMMA-ABES, BH, 25 junho. 10. Silva (1991). Sem. "Silêncio e Saúde". SMMA-ABES, BH, 25 junho. 11. Nava (1958). Psicologia Prática. Itatiaia, BH, 108 p. 12. Cantrell (1974). The laryngoscope, LXXXIV, 10(2 supl), 1-55. 13. Babisch (1991). Traffic Noise as a Risk Factor for Mycardial Infarction. Symp. "Noise and Disease", Berlin. 14. ABTN (1987). NMBR/10152. ABNT, RJ. 15. Lukas (1971). Relative frequency of five sleep stages and relative sensitivity to tones during the seep stages. Am Ind Hyg Conf, Toronto 16. Ollerhead (1973). Appl. Ergon., 4(3), 130-138. 17. Schultz et al (1976). Recommendations for changes in HUD's noise policy standards. DC, Dept Housing & Urban Develop.