a comparative study of noise pollution levels in ilorin metropolis, nigeria

A Comparative Study of Noise Pollution Levels in Some Selected Areas in Ilorin Metropolis, Nigeria

Oyedepo S.Olayinka1

Saadu A.Abdullahi (Ph.D)2

1Department of Mechanical Engineering,Covenant University, Ota, Ogun State2Department of Mechanical Engineering, Kwara State Polytechnic, Ilorin, Kwara State.

Correspondence: Oyedepo S Olayinka E-mail: [email protected]

ABSTRACTThe noise pollution is a major problem for the quality of life in urban areas. This study was conducted to compare the noise pollution levels at busy roads/ road junctions, passengers loading parks, commercial, industrial and residential areas in Ilorin metropolis. A total number of 47- locations were selected within the metropolis. Statistical analysis shows significant difference (P<0.05) in noise pollution levels between industrial areas and low density residential areas, industrial areas and high density areas, industrial areas and passengers loading parks, industrial areas and commercial areas, busy roads/ road junctions and low density areas, passengers loading parks and commercial areas and commercial areas and low density areas. There is no significant difference (P>0.05) in noise pollution levels between industrial areas and busy roads/ road junctions, busy roads/ road junctions and high density areas, busy roads/ road junctions and passengers loading parks, busy roads/ road junctions and commercial areas, passengers loading parks and high density areas, passengers loading parks and commercial areas and commercial areas and high density areas. The results show that Industrial areas have the highest noise pollution levels (110.2 dB(A)) followed by busy roads/ Road junctions (91.5 dB(A)), Passengers loading parks (87.8 dB(A)) and Commercial areas (84.4 dB(A)). The noise pollution levels in Ilorin metropolis exceeded the recommended level by WHO at 34 of 47 measuring points. It can be concluded that the city is environmentally noise polluted and road traffic and industrial machineries are the major sources of it. Noting the noise emission standards, technical control measures, planning and promoting the citizens awareness about the high noise risk may help to relieve the noise problem in the metropolis.

Key words: Noise pollution, environmental noise, industrial noise, Ilorin, health hazard

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mailto:[email protected]

1.0 INTRODUCTIONNoise, a by-product of urbanization and industrialization, is increasingly recognized as an environmental nuisance that affects human health and well being (Mansouri et al, 2006). City noise levels can be investigated in three different ways as traffic and transportation; industrial activities; Sport, marketing and entertainment facilities (Sukuru et al, 2006).In comparison to other pollutants, the control of environmental noise has been hampered by insufficient knowledge of its effects on human and lack of defined criteria. Noise pollution is a significant environmental problem in many rapidly urbanizing areas. This problem is properly not recognized despite the fact that it is steadily growing in developing countries. It is well established now that noise is a potential hazard to health, communication and enjoyment of social life. It is becoming an unjustifiable interference imposition upon human comfort, health and quality of life (Ahmad, 1998).Noise as a physical pollutant is not easily recognized. This is because the sensitivity of human ear gets automatically adjusted to the ambient level of sound and so slow increases in the ambient level go unnoticed. Therefore, noise continues to do the damage silently. Pollution, in general, is a by-product of some essential function or activity. Therefore it is almost impossible to completely eliminate the pollutant, but it can be controlled or reduced. Most of the pollutants can be tolerated only up to a certain level, the level being dependent on the type of the pollutant. When the level of pollution continues to increase, it becomes necessary to know the amount by which the permissible limit has been exceeded so that their increase can be checked by the introduction of suitable regulations. To know the level of pollution the pollutant has to be measured. In the case of noise pollution, measurement is all the more essential because of the incapability of our auditory system to recognized slow changes (Sampath et al, 2004).In Nigeria, the problem of noise pollution is wide spread. Several studies report that noise level in metropolitan cities exceeds specified standard limits. A study by Ugwuanyi et al (2004) conducted in Makurdi, Nigeria found that the noise pollution level in the city was about 3 dB(A) to 10 dB(A) above the recommended upper limit of 82 dB(A). Onuu and Menkiti (1993) also found that the peak noise level ranges between 86-106 dB(A) in Aba and Uyo, Nigeria. This noise level is higher than the recommended level of 60 dB(A) for commercial and residential areas. Ighoroje et al (2004) investigated the level of noise pollution in selected industrial locations in Benin City, Nigera. The average ambient noise level in Sawmills, Electro-acoustic market and food processing industrial areas was determined to be above 90 dB(A). This noise level is well above the healthy noise level of 60 dB(A).The noise pollution is not a unique problem for developing countries like Nigeria only. Many researches have revealed that, more than 130 million people in Europe suffer from exposure to noise levels above 65 dB(A) ( CEC, 2000). Bond (1996) reports that 16% of people in Europe are expose to 40 dB(A) or more of traffic noise in their bed rooms at night compare it with WHO’s average estimates of 30 to 35 dB(A) for undisrupted sleep. WHO has proposed the time base guideline for LAeq for 16h daytime and 8h night-time. The environmental noise level of 70 dB(A) LAeq, 24h was recommended by WHO for industrial, commercial, shopping and traffic areas, indoors and outdoors areas to prevent impairments (Birgitta et al, 1999).

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Depending on the duration, volume of noise and distance from noise source, the effects of noise on human health and comfort are divided into four groups: physical effects, such as hearing and ear burning; physiological effects, such as increased blood pressure , irregularity of heart rhythms and ulcers; psychological effects, such as disorders, irritability, annoyance and stress; and finally performance effects, such as reduction of productivity and lack of understanding what is heard (Yilmas and Ozer, 2005; Saadu, 1988; Tekalam, 1991; Narender and Davar, 2004; Okah-Avae,1996).It is sad to know from the investigations by Saadu et al (1998), Onuu and Menkiti (1993), Ugwuanyi et al (2004) , unpublished works of Saadu (1988) and Agbendeh (2000) that Nigerians are noisy people. In Nigeria, there is no legal frame work upon which noise pollution can be abated. Federal Environmental Protection Agency (FEPA) in Nigeria only provided daily noise exposure limits for workers in industry (i.e 90 dB(A) for 8h exposure).In short, the Nigerian Government and her citizenry appear not to be conscious of the present and future impacts of noise induced health hazards in their environment. Unless and until measures are taken to control the level of noise, the ongoing urbanization and industrialization may complicate the problem so much that it becomes incurable.Ilorin is one of the biggest cities in the Middle belt zone of Nigeria. The most important factors raising the noise pollution in the city in the last two decades are the increased number of cars, the increased population and industrialization. The population has increased from 423,340 in 1980 to 902,131 in 2006 (NPC, 2006). The city has been subjected to persistent in road traffic and commercial activities due to overall increase in prosperity, fast development and expansion of economy. Very few studies have been carried out to investigate and assess noise pollution in Ilorin metropolis. Saadu (1988), carried out research on community and occupational noise survey and analysis in the city of Ilorin. Many recent survey changes in demography and urban boundary in the city have taken place and consequently, further investigation of this phenomenon is needed. Oyedepo and Saadu (2008) studied the changing noise climate of Ilorin metropolis. In the study, a noise level in Ilorin was investigated and noise map for the city was developed.This study was carried out to determine: (i) the noise pollution levels in selected locations (commercial areas, busy roads/road junctions, passengers loading parks, residential and industrial areas) in Ilorin metropolis. (ii) if there is significant difference in noise pollution levels (LNP) in the selected locations.

2.0 Materials and Methods2.1 Study AreaThis research is based on the results of outdoor sound level measurements carried out in October 2004 and July 2005 at 47 different locations (12 commercial areas, 12 busy roads/road junctions, 6 passengers loading parks, 6 high density residential ,6 low density residential and 5 industrial areas) in Ilorin metropolis, the capital city of Kwara state. Table1shows the locations selected for the noise level measurements in Ilorin metropolis. Figures1 and 2 show an overview of Ilorin metropolis showing the locations of noise measurements for this study and the population growth of the metropolis respectfully.

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Table 1: Locations selected for the noise level measurements in Ilorin MetropolisDesignation No

Location DesignationNo

Location

123456789101112131415161718192021222324

Ita-AlamuOffa GarageGaa-AkanbiGRATankeBasinJebba RoadMaraba Yoruba RoadChallenge JunctionRailway Station Unity RoadNigerAgo MarketEmir’s RoadOpo MaluIpata MarketOja –GboroGambariOja-ObaGegeleIta-AmoduTaiwo RoadAgbooba Junction

2526272829303132333435363738394041

423327

332

Baboko GarageAgakaOja-TitunKuntuUnilorin JunctionAdewoleSawmill-GarageAsa Dam RoadGeri AlimiAirportAdetaPakataOlojeOkeleleShao GarageSobi RoadGeneral Hospital Round-aboutBalogun FulaniMinerals crushing millsSoft drink bottling Ind.Beer brewing & bottlingInd.Tobacco making Ind.Mattress making Ind.

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Fig. 1 Overview of Ilorin metropolis showing the locations of noise measurements Throughout this study (Source: Survey Division, Min. of Lands & Housing,Ilorin, Kwara State)

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Figure 2 The Increase in Population of Ilorin

1950 1960 1970 1980 1990 200020006

204,257

252,784

317,729

423,340

557,568

754,662

902,131

0

100000

200000

300000

400000

500000

600000

700000

800000

900000

1000000

Years

Po

pu

lati

on

2.2 Instrumentation and Noise SurveyInstrumentation for the field measurements consisted of precision grade sound level meter (according to IEC 651, ANSI S1.4 type), ½- in. condenser microphone and ⅓- octave filter with frequency range and measuring level range of 31.5Hz – 8 KHz and 35-130dB respectively. The instruments were calibrated by the internal sound level calibrator before making measurements at each site. All the instruments comply with IEC standards.2.3 Assessment of Community Noise SurveyFor community noise survey, measurements were made at street level (at road junctions, market centers, passengers loading parks and residential areas). The instrument was held comfortably in hand with the microphone pointed at the suspected noise source at a distance not less than 1 m away from any reflecting object. L Ai (A-weighted instantaneous Sound pressure level) measurements were recorded at intervals of 30 seconds for a period of 30 minutes, giving 60 meter readings per sampling location. This procedure was carried out for morning (7:30 -8:00 a.m), afternoon (1:00 – 1:30 p.m), evening (4:00-4:30 p.m) and night (8:30 -9:00 p.m) measurements. From these readings, commonly used community noise assessment quantities like the exceedence percentiles L10, and L90, the A-weighted equivalent sound pressure level, LAeq, the daytime average sound level, LD, the day-night average sound level, LDN, the noise pollution level, LNP and the traffic noise index, TNI were computed. These noise measures are defined as follows (Saadu et al, 1998):

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Where LAi is the ith A-weighted sound pressure level reading dB, N is the total number of readings, LAeq is the A-weighted equivalent sound pressure level, LAeqM is the equivalent sound pressure for the morning measurement, LAeqA is the equivalent sound pressure level for the afternoon measurement, LAeqE is the equivalent sound pressure level for the evening measurement, LAeqN is the equivalent sound pressure level for the night measurement, LN is night time noise level, LD is day time noise level, L10 is the noise level exceeded 10% of the time, L90 is the noise level exceeded 90% of the time, LNP is noise pollution level, LDN is day-night noise level, TNI is the traffic noise index. Tables 7-11 show the noise levels measured in commercial areas, road junctions/ busy roads, passengers loading parks, high density residential areas and low density residential areas.2.4 Assessment of Industrial Noise ExposureFor industrial noise survey, noise levels were measured at the positions of the employees’ heads while they kept their work posture. A total number of 74-industrial machineries were assessed for noise emission: minerals crushing mills (16), soft drink bottling industry (12), beer brewing and bottling industry (14),tobacco making industry (14), and mattress making industry (18). For each of the selected machines in the study, five measurements were taken at interval of 30 seconds for a period of 15 minutes. The experimental apparatus used, measures both time varying (non-impulsive) noise and impulsive noise. Occurrence of impulsive noise was noted during measurement and analyzed in this study. Each employee was assessed for a period of 8-working hours per day and 48-working hours per week in each of the selected industries.2.4.1 Time varying noise exposureIn the case where workers experience time-varying noise exposure because the noise is cyclical or varies unpredictably at their work station or because they move around the department or plant in performing their job, the ISO R1999 (Saadu,1988)standard provides for summing the series of partial exposure that such workers receive during their work period. The noise levels so measured should be grouped in classes with width of 5 dB each, the level and total duration within the week being recorded for each class. The total duration of exposure of each class in a week is then converted to partial noise exposure index utilizing table of partial noise exposure indices. The composite noise exposure index is then added up and the corresponding equivalent continuous sound level, LAeq, was read from the chart of relationship between equivalent continuous sound level and composite noise exposure index.

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The above procedure was applied in computing the equivalent continuous sound level (non-impulsive noise), LAeq, in the industries surveyed. Tables 8-12 show the computed equivalent continuous sound level (LAeq) for the industries surveyed. The noise pollution level can be computed by using the relation (ISO/R131- 1959) (Peterson and Gross, 1974):LNP = LAeq +19.88 (7)2.4.2 Impulse Noise LevelThe new Draft International Standard, “Determination of occupational noise exposure and estimation of noise – induced hearing impairment “(ISO/DIS 1999-1981) stipulates that so far the un-weighted instantaneous sound pressure level does not exceed 145 dB(A), impulse noise and non-impulse noise should not be considered independently but should be included in the A-weighted daily noise exposure averaged on an equal energy basis.The draft recommendation, in effect, permits the combination of exposures to different kinds of noise in the same daily duration for estimating the sound exposure level (SEL), LAeq (8h), which is defined as equivalent A-weighted exposure level for an 8-hour daily working period. This is given by (Saadu,1988) :

(8)

WhereLAj is the A-weighted sound pressure level of a continuous noise

tj is the duration of LAj in hours,

q is the number of different values of LAj

LAi is the A-weighted sound pressure level (peak) of a single impulse noiseni is the frequency of occurrence of LAi

k is the number of different values of LAi

N is the number of values of LAi given by

The noise exposure records of the workers in the soft drink bottling industry, minerals crushing mills and beer brewery and bottling industry were computed based on the above equation. Tables 13 -14 show the noise expose records.

2.5 AnalysisThe indoors and outdoors ambient noise measurements carried out in October 2004 and July 2005 at 47 locations in Ilorin metropolis are to be analyzed.In table 2, the noise pollution levels (LNP) for commercial centers is presented to illustrate the full data set. Fisher’s distribution and Scheffe’s Post Hoc tests were made on the full data set.Using one-way analysis of variance, a null hypothesis of the first test isHo: μ1 = μ2

That is, the means of populations from which the samples are drawn are equal.In this test, two independent estimates of the population variance are (i) within group variance estimate which deals with how different each of the values in a given sample is

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from other values in the same group (ii) between group variance estimates which deals with how different the means of various samples (or groups) are from each other. These are computed as follows:The total sum of squares is

(9)

Where (10)

The sum of squares between groups is

(11)

Where k is number of groupsSum of squares within groups is

(12)Computation of various degrees of freedoms is as follows:Degree of freedom between groups isdfB = k – 1 (13)Degree of freedom within groups isdfW = N – k (14)Total degrees of freedom isdfT = N – 1 = dfB + dfW (15)Where N is the total number of observationsComputation of mean squares between and within groups is as follows:Mean square between the groups is

(16)

Mean square within the groups is

(17)

Finally, the Fisher’s ratio is computed as

(18)

The second test, known as Scheffe’s Post Hoc Test is to be carried out on the data set. This test ascertains the pair wise difference responsible for significant difference (if any) in obtained F-values in Fisher’s distribution test (ANOVA test).The technique behind this test is to moderate a critical value of F (usually α = 0.05) by a factor k – 1. So, we obtain

(19)Next we adjust the MSSW of Fisher’s test by the factor k – 1 to obtain

(20)

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Where Nk are the numbers of elements in each sample. The two tests were made with α = 0.05, i.e probability of making an error by saying the null hypothesis is false when it is actually true. On the other hand, (1- α ) is the probability of making the right decision when the null hypothesis is true, or the confidence level ( Adedayo, 2000).Table 2: Noise pollution levels (LNP) for commercial centres

x 968281818681939290688380

11.6 134.56-2.4 5.76-3.4 11.56-3.4 11.561.6 2.56-3.4 11.568.6 73.967.6 57.765.6 31.36-16.4 268.96-1.4 1.96-4.4 19.36

3.0 Results and Discussion The results for complete data set of noise pollution levels (LNP) in all the locations surveyed are presented in Table 3. Relevant parameters to determine F- values in Fisher’s test (ANOVA test) are computed. A glance look at Table 3 shows that the average noise pollution of locations surveyed ranges from 59- 110.2 dB(A). The lowest and highest noise pollution levels were recorded at low density residential areas and industrial areas respectively. The major sources of noise pollution at the selected industries for this study are the industrial machineries such as Vibratory crusher, grinding and filling machine (at solid minerals crushing mills), electric generator, ammonia compressor and bottle washing machines (at soft drinks bottling and beer brewing and bottling industries). The noise exposure pattern of these machineries is impulsive in nature. The next locations of high noise pollution level are the road junctions/ busy roads. The major sources of noise at these locations include road traffic, vehicle horn, rolling tires etc.

Table 3: Noise Pollution Levels in dB(A) for all Locations No. of Location

LocationCommercial Road Junctions/ Passengers High Density Low Density IndustrialCentres Busy Roads Loading Parks Residential Areas Residential Areas Areas

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(X1) (X2) (X3) (X4) (X5) (X6)123456789101112

96 106 90 76 64 10982 90 81 72 63 11181 85 89 76 52 11181 89 94 86 61 10586 88 86 67 57 11581 87 87 69 5693 10292 86 90 9468 9083 9580 86

1013 1098 527 446 353 551

84.4 91.5 87.8 74.3 58.8 110.2 86145 100952 46383 33382 20875 60773

85514.1 100467 46288.2 33152.7 20768.2 60720.2

Tables 4 and 5 show the mean number and standard deviation and ANOVA source table respectively of noise pollution levels (LNP) of all the surveyed locations.

Table 4: Means and standard deviations of noise pollution levels

1 (n= 12) 2 (n=12) 3 (n=6) 4 (n=6) 5 (n=6) 6 (n=5)Mean 84.4 91.5 87.8 74.3 58.8 110.2StandardDeviation

7.25 6.36 3.92 6.18 4.22 3.25

Table 5: ANOVA source table

Source SS df MSS

Between samples 8524.24 5 1704.85Within samples 1596.98 41 34.72 49.11 3.97Within Total 1021.23 46

From Table 5, F-values calculated is 49.11 while the tabulated values (F0.05,5,41) at 95% confidence level is 3.97 (Lipson and Seth,1973).Since the calculated F-value is greater than the tabulated, hence, there is a significant difference (P< 0.05) in noise pollution levels in all the locations surveyed based on the data analyzed.Since the obtained F-value leads to the result being significantly difference in Fisher’s test, we now wish to find out which pair wise difference was responsible for the significant difference. Could it be pair wise of (μ1 and μ2) or (μ1 and μ3)? To ascertain which pair wise responsible for significant difference, a test known as Scheffe’s Post Hoc test is carried out. This test is an appropriate measure for all comparisons of mean after Fisher’s test (ANOVA test).

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Using equation (20) and substituting the appropriate parameters we have

= 24.44Next, we compare this value of SSE with difference in pair wise mean. Any pair with difference more than SSE is responsible for the significant difference in Fisher’s value.

Table 6: Table of pair wise difference

From Table 6, the pair wise differences between and (51.4) , and (35.9), and (25.8), and (32.7), and (29) and and (25.6) are greater

than the critical F-value (SSE).Hence, these pairs are responsible for the significant difference in F-value.This analysis reveals that there is significant difference (p< 0.05) in noise pollution levels between industrial areas and low density residential areas; industrial areas and high density residential areas; industrial areas and commercial areas; road junctions/ busy roads and low density residential areas; passengers loading parks and low residential areas and commercial areas and low density residential areas. But there is no significant difference (p> 0.05) in noise pollution levels between industrial areas and road junctions/ busy roads; industrial areas and passengers loading parks; road junctions/ busy roads and high density residential areas; road junctions/ busy roads and passengers loading parks; road junctions/ busy roads and commercial areas; passengers loading parks and commercial areas and commercial areas and high density residential areas.At 95% confidence level, the F-value tabulated is less than the calculated F-value. Hence, we reject the null hypothesis and infer that the difference in noise pollution level is significant.Generally, in Nigerian urban areas noise exposure levels vary from one location to another. Noise pollution exposure in industrial areas, road junctions/ busy roads, commercial areas and passengers loading parks are relatively high when compare with that of low density residential areas. This makes industrial employees, residents living close to road junctions/ busy roads, traders, police men and traffic warders to be exposed to excessive noise pollution. These group of people are prone to various noise induce problems.Figure 3 shows variation of noise pollution levels with locations in Ilorin metropolis. The highest average noise pollution level was recorded at industrial areas (110.2dB (A)) followed by road junctions/ busy roads (91.5 dB(A)) , Passengers loading parks (87.8 dB(A)) and commercial areas (84.4 dB(A)). These noise pollution levels are higher than those reported by Saadu (1988) for all the locations chosen for this study in Ilorin metropolis. This is basically due to increased in population density, commercial activities, industrial activities and traffic volume.

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Tables 7 to 11 show the Traffic Noise Index (TNI) of Commercial areas, Road junctions/ busy roads, Passengers loading parks, High density residential areas and Low density residential respectively in Ilorin metropolis. The average Traffic Noise Index (TNI) ranges from 70 to 84 dB(A) at commercial areas; 86 to 98 dB(A) at road junctions/ busy roads; 80 to 89 dB(A) at passengers loading parks; 62 to 70 at high density residential areas and 36 to 54 dB(A) at low density residential areas. It should be noted that a TNI of 74 dB(A) has been reported to be associated with less than 3% annoyance in social survey ( Ahmad et al , 2006).Hence, road junctions/ busy roads and low density residential areas have the highest and lowest annoyance responses due to traffic noise.Tables 12 to 16 show the noise exposure levels in the industries surveyed in this study. The average equivalent continuous noise level (LAeq ) ranges from 82.8- 94.83 dB(A).The highest and lowest noise pollution level (LNP) were recorded as114.77 and104.92 dB(A) at minerals crushing mills and mattress making industry respectively. The impulse noise level ranges from 105.9 – 110.9 dB(A). Based on Occupational Safety and Health Administration (OSHA) criteria, the computed daily Time Weighted Average (TWA) exposure of the industries ranges between 73.83 to 95.94 dB(A). The highest exposure to 8- hour TWA noise is experienced by the operator of washing machine II in soft drink bottling industry.In all the locations surveyed, the noise levels are very much higher than the levels reported for living rooms. The bedroom noise levels of 25-30 dB(A) reported by Davies and Masten (2004) has been exceeded in all locations of Ilorin metropolis during the night time, resulting in more possible sleep disturbance due to traffic noise. It should be noted that the World Health Organization (WHO), recommends a noise level of less than 35 dB(A) based on the continuous equal energy concept for the restorative process of sleep (Mufuruku, 1997).

4.0 CONCLUSIONComparative study of noise pollution levels in Ilorin metropolis was carried out at 47-different locations to compare the level of noise pollution from community and industrial noise sources .A statistical analysis carried out shows that the noise pollution levels (LNP) differs significantly (P<0.05) at α = 0.05 between industrial areas and low density residential areas; industrial areas and high density residential areas; road junctions/ busy roads and low density residential areas; passengers loading park and low density residential areas and commercial areas and low density residential areas. But no significant difference (P>0.05) in noise pollution levels between industrial areas and road junctions/ busy roads, industrial areas and passengers loading parks, road junction/ busy roads and high density residential areas, road junctions/ busy roads and passengers loading parks, passengers loading parks and commercial areas and commercial areas and high density residential areas. The statistical analysis paired all the locations surveyed into two zones: zone of similar noise pollution levels and zone of different noise pollution levels.The results of this study show that the average noise pollution levels in Ilorin metropolis ranges from 58.8 dB(A) to 110.2 dB(A) with the highest average noise pollution at industrial areas (110.2 dB(A)) followed by road junctions/ busy roads(91.5 dB(A)), passengers loading parks (87.8 dB(A) and commercial areas ( 84.4 dB(A)). This result differs from that of Braj and Jain (1995) that reported the measurements of noise levels in some residential, industrial, and commercial areas in the capital city of India, Delhi that

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commercial areas have the highest noise levels followed by industrial and residential areas. The reason for having highest noise pollution levels at industrial areas in Ilorin metropolis is possibly due to aging and poor maintenance of the industrial machines of the industries selected for this study as observed when noise measurement was carried out.Due to few number of industries in this metropolis compare to traffic volume and commercial activities, the major sources of noise pollution can be associated to traffic noise which include the ambient noise sources from exhaust, rolling stocks and tires of motor vehicles, vehicle mounted loudspeaker; human conversation in the market place, hawking, record player and loudspeaker use to call on passengers into commercial vehicles at the passengers loading parks and worshippers at religious centers.This investigation reveals that noise pollution levels at 34 of 47 measurement points in Ilorin metropolis exceeded recommended level of 80 dB(A) by values of 1 to 34 dB(A). Hence, the present status of noise pollution in Ilorin metropolis poses severe health risk to the populace. Furthermore, discomfort and irritation being caused by the pollution can drastically reduce productivity, both in public service and private sectors. In addition, some areas may soon reach the threshold of pains, and lead to permanent loss of hearing and death.

5.0 RECOMMENDATIONSDue to these adverse effects of noise pollution on the populace a number of action plans can be taken to abate the environmental and industrial noise pollution in Nigeria. These include: technical, planning, behavioural and educational solutions. For industrial noise pollution, firstly, noise should be reduced from the source through proper and regular maintenance, replacement of worn out parts, replacing old machines with new ones and provision of damper at the base of machines. Secondly, minimizing noise intensity transmitted along its transmission path by covering outer surfaces of machine rooms with sound absorbent materials, Green belt design and use of noise protective measures. In environmental noise pollution, since transport infra-structures can be recognized as major sources of noise, technical actions on the transport systems can produce interesting results. Possible technical controls include (i) changes in road profiles, (ii) low noise pavements (porous or porous elastic) type, (iv) effective repairs to the silencers and vehicle suspensions so as to reduce exhaust and rolling stock noise, (v) reduction limitations or restrictions on traffic (types of vehicles, speed, hours of access etc) and (vi) building of acoustic barriers along the sides of heavily traveled highways running through residential areas. Transportation and land planning (private versus public transportation, bus lanes, parking areas, shuttle buses and pedestrian areas) are important components of plan. Since noise also results from the citizen’s behavior (driver, music player, hawker etc), information and education campaigns usually produce good results in the long term. Information on different actions and on the results should be well disseminated and should correspond to general aims and action plans. There is need to establish environmental noise impact criteria levels for various land use purposes. These criteria levels would enable impacts to be determined. The authorities should pass laws to check excesses of the sources of high noise levels. Other professionals such as town planners, architects and environmental engineers as well, should have the problems of

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environmental noise pollution in mind when siting new roads, shopping centers, schools, hospitals and both commercial and residential houses in general.Table 7: Commercial areas noise levelsSite Period of the day Noise level descriptors(dB (A)) LAeq L10 L90 TNI LNP LD LN LDN

Oja-Oba Market Morning 82 87 71 105 98 Afternoon 84 88 74 100 98 83 Evening 85 89 78 92 96 Night 76 81 67 93 90 83 89

Oja- Ago Market Morning 69 73 62 76 80 Afternoon 71 75 66 72 80 70 Evening 78 82 71 85 89 Night 66 66 53 75 79 75 81

Oloje Market Morning 76 81 65 99 92 Afternoon 72 76 65 79 83 74 Evening 71 74 66 68 79 Night 59 62 53 59 68 68 76

Oja-Titun Market Morning 68 71 59 77 80 Afternoon 76 79 63 97 92 74 Evening 74 77 62 92 89 Night 51 54 43 57 62 71 78

Ipata Market Morning 73 78 64 90 87 Afternoon 74 79 64 94 89 74 Evening 66 72 57 87 81 Night 72 56 40 74 88 69 77 Oja-Gboro Morning 78 71 59 77 80 Market Afternoon 75 79 63 97 92 72 Evening 76 77 62 92 89 Night 76 54 43 57 62 76 83 Gegele Market Morning 77 80 63 101 94 Afternoon 80 84 66 108 98 79 Evening 84 87 75 93 96 Night 69 74 60 86 83 81 87

Gambari Market Morning 79 81 68 90 92 Afternoon 86 90 77 99 99 84 Evening 83 86 73 95 96 Night 74 73 66 64 81 81 88

Agaka Morning 78 80 70 80 88 Shopping Afternoon 83 86 76 86 93 81 center Evening 82 84 75 81 91 Night 75 76 63 85 88 80 87

Yoruba Road Morning 47 60 51 57 56 Shopping Afternoon 68 70 60 70 78 65 center Evening 69 74 59 89 84 Night 47 50 43 41 54 66 72

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Station Morning 78 80 73 71 85 shopping Afternoon 75 79 69 79 85 77 center Evening 76 78 73 63 81 Night 72 74 66 68 80 75 81

Taiwo Road Morning 66 69 59 69 76shopping Afternoon 75 79 69 79 75 73 center Evening 74 74 65 71 86 Night 69 73 61 79 81 72 79

Mean Morning 73 76 64 83 84 Afternoon 77 80 68 88 89 76 Evening 77 80 68 84 88 Night 67 66 55 70 76 75 82

Table8: Traffic noise levels at major road junctions /busy roadsSite Period of the day Noise level descriptors(dB (A)) LAeq L10 L90 TNI LNP LD LN LDN

Challenge Morning 89 94 75 121 108 Junction Afternoon 88 93 74 120 107 89 Evening 86 94 74 124 106 Night 81 87 65 123 103 84 92

Ita- Amodu Morning 77 81 72 78 86 Junction Afternoon 81 86 71 101 96 79 Evening 81 84 72 90 93 Night 76 80 70 80 86 79 85

Unilorin mini- Morning 70 75 63 81 82Campus round- Afternoon 72 77 63 89 86 71 about Evening 72 78 60 102 90 Night 69 71 60 74 80 71 77

General Hospital Morning 74 79 69 79 84 Junction Afternoon 77 82 69 91 90 76 Evening 77 81 70 84 88 Night 76 80 62 102 94 77 83

Agbooba - Morning 78 81 71 81 88 Surulere Afternoon 77 80 73 71 84 78 Junction Evening 81 85 71 97 95 Night 77 81 72 87 86 79 85 Unity road Morning 78 81 72 78 87 Afternoon 78 83 73 83 88 78 Evening 78 82 73 79 87 Night 77 76 66 76 87 77 84

Emir’s road Morning 80 82 71 85 91 Afternoon 85 89 71 113 103 83 Evening 87 92 70 128 109 Night 82 86 64 122 104 85 91

Asa Dam road Morning 72 77 64 86 85

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Afternoon 75 76 65 89 86 74 Evening 74 77 66 80 85 Night 73 64 49 79 88 74 80

Sobi road Morning 81 84 71 93 94 Afternoon 81 83 71 89 93 81 Evening 85 88 74 100 99 Night 76 77 63 89 90 83 89

Pakata road Morning 74 77 68 74 83 Afternoon 75 79 63 97 91 75 Evening 75 80 66 92 89 Night 74 73 52 106 95 75 81

Jebba road Morning 72 76 54 112 94 Afternoon 75 78 53 123 100 73 Evening 69 74 58 116 93 Night 68 72 46 120 94 68 75

Adeta Morning 73 75 68 66 80 Junction Afternoon 72 73 59 85 86 73 Evening 70 74 64 74 80 Night 74 79 55 121 98 72 79


Table9: Passengers loading parks noise levelsSite Period of the day Noise level descriptors(dB (A)) LAeq L10 L90 TNI LNP LD LN LDN

Maraba garage Morning 74 79 63 97 90 Afternoon 81 81 59 117 103 79 Evening 72 75 62 84 85 Night 69 67 54 76 82 71 80

Shao garage Morning 76 71 60 74 87 Afternoon 71 74 64 74 81 74 Evening 72 76 66 76 82 Night 62 65 55 65 72 69 77

Offa garage Morning 79 83 71 89 91 Afternoon 74 78 66 84 86 72 Evening 81 86 73 95 94 Night 73 77 66 80 84 79 85

Baboko garage Morning 80 84 74 84 90 Afternoon 82 88 74 100 96 81 Evening 83 86 77 83 92 Night 81 86 71 101 96 82 88

Saw-mill garage Morning 81 81 72 78 90

17

Afternoon 78 80 72 74 86 80 Evening 76 79 72 70 83 Night 71 75 62 84 84 74 82 Geri-Alimi Morning 79 80 71 77 88 garage Afternoon 75 77 65 83 87 78 Evening 76 80 73 71 83 Night 73 77 62 92 88 74 82


Table 10: Residential area noise levels (high density areas)Site Period of the day Noise level descriptors(dB (A)) LAeq L10 L90 TNI LNP LD LN LDN

Opomalu Morning 64 68 58 68 74 Afternoon 66 70 59 73 77 65 Evening 66 69 59 69 76 Night 65 68 58 68 75 66 72

Okelele Morning 62 63 57 51 68 Afternoon 56 58 52 46 62 60 Evening 71 75 69 63 82 Night 66 70 61 67 75 69 75

Kuntu Morning 63 73 57 91 79 Afternoon 60 63 52 66 71 62 Evening 68 67 56 70 79 Night 65 60 50 60 75 67 73

Niger Morning 64 67 60 58 71 Afternoon 77 80 61 107 96 74 Evening 76 75 62 84 89 Night 76 80 68 86 88 76 82

Balogun fulani Morning 60 63 57 51 66 Afternoon 62 66 56 66 72 61 Evening 61 63 52 66 72 Night 55 56 52 38 59 59 66 Gaa-Akanbi Morning 66 69 62 60 73 Afternoon 56 60 51 57 65 63 Evening 65 69 60 66 74 Night 57 60 52 54 65 63 66


Table 11: Residential area noise levels (low density areas)Site Period of the day Noise level descriptors(dB (A)) LAeq L10 L90 TNI LNP LD LN LDN

18

Tanke Morning 59 55 46 52 68 Afternoon 51 47 40 38 64 57 Evening 57 53 43 53 67 Night 54 55 53 31 56 56 63

GRA Morning 61 58 46 64 71 Afternoon 57 60 46 72 67 59 Evening 55 59 47 65 61 Night 56 59 54 44 52 56 53

Basin Morning 45 48 41 39 52 Afternoon 41 43 38 28 46 43 Evening 46 49 43 37 52 Night 55 56 55 29 56 53 59

Adewole Morning 57 54 43 57 68 Afternoon 47 51 38 60 60 54 Evening 51 52 43 49 60 Night 45 47 38 44 54 49 57

Ita-Alamu Morning 49 52 43 49 58 Afternoon 49 54 45 51 58 49 Evening 48 52 43 49 57 Night 49 51 45 39 55 49 55 Airport Morning 51 52 39 61 64 Afternoon 43 41 33 35 51 49 Evening 44 44 32 50 56 Night 44 40 33 31 51 44 52

Mean Morning 54 53 43 54 64 Afternoon 48 49 40 47 58 52 Evening 50 52 42 51 60 Night 51 51 46 36 58 51 57 M- Morning; A- Afternoon; E- Evening; N- Night

Tables 8 : Exposure Records Table of Employee in Beer brewing and bottling industry

Noise Source Sound pressure Level

Total duration per wk in hr(Obtained by interview)

Partial Noise Exposure Index(PNE)

LAeq LNP

(dB(A)) (dB(A))

Boiler

Air.Compressor1

Air Compressor2

908580

908580908580

101614

71815101218

25155

2015525105

85.1

84.9

84.9

19

Air Compressor3

Air Compressor4

Ammonia Compressor1

Ammonia Compressor2

Pump

Electricity Generator

Filling & Crowning M/c

Washing M/c

Full Sighting M/c

Case Packing M/c

Labeling M/c

908580

908580

908580

908580

100959085

10095

959085

959085

959085

100959085

908580

151213

151015

82012

101515

2.27.81020

1525

251510

9301

10255

313186

201010

40105

40105

20155

25155

50652515

400200

2004010

70750

80654

75110455

50105

86.2

86.2

84.9

85.1

93.2

97.7

94.6

92.5

92.8

94.1

87.2

20

Mean 89.2

Tables 9 : Exposure Records Table of Employee in Soft Drink bottling industryNoise Source Sound pressure

LevelTotal duration per wk in hr(Obtained by interview)


LAeq(dB(A))

Boiler

Carbon Dioxide Compressor

Ammonia Compressor

Pump1

Pump 2

Pump 3

Electricity Generator 1

Filling & Crowning M/c

Washing M/c1

Washing M/c 2

908580

908580

959086

959085

959085

959085

1009590

9590

959085

959085

102613

9255

92010

42312

62013

52410

16202

2019

8265

6284

25205

25200

705010

306510

455010

406510

400505

16050

65654

70750

85.6

85.4

92.2

89.5

89.5

90.9

96.5

93.5

92.5

92.5

21

Full Sighting M/c

Case Packing M/c

959085

100959085

10255

313186

80654

75110455

Mean

92.8

94.1

91.18

Tables 10 : Exposure Records Table of Employee in Tobacco making industryNoise Source Sound pressure



LAeq(dB(A))

Boiler 1

Boiler 2

Vacuum pump

Vacuum Compressor 1

Vacuum Compressor 2

Auto Fixing M/c

Mechanical Fixing M/c


90

9590

105908580

959085

959085

9590

85

105100

37.5

2.535

2.510205

101215.5

11.51313

2.535

37.5

1.11.4

100

2090

20025150

803015

953510

2090

30

9035

90

90.6

94.2

91.4

92.5

90.6

84.8

92.9

22






Air Compressor

Packing M/c(Automated)

9080

Not in use

1051009080

1051009080

1051009080

1051009080

908580

9085

4.230.8

Not in use

1.21.03.531.8

1.41.34.030.8

1.51.04.031

1.21.74.130.5

81316.5

17.520

1010

-

90251010

105351010

120251010

75110455

20105

4515

Mean

-

92.3

93.2

93.5

92.8

84.9

88.5

90.87

Tables 11 : Exposure Records Table of Employee in Mattress making industryNoise Source Sound pressure


Partial Noise Exposure

LAeq(dB(A))

23

Index(PNE)Electricity Generator 1


Automated foam production M/c

Trolley 1

Trolley 2

Trolley 3

Trolley 4

Sowing & Knitting M/c 1






Sowing &

10080

10085

8580

908580

908580

908580

908580

8580

8580

8580

8580

8580

8580

85

1624

1723

1525

51718

61816

82012

81220

1921

2515

2218

1921

1525

2020

19

4005

45020

155

15155

15155

20155

20105

155

205

155

155

155

155

15

95.6

96.8

82.8

84.4

84.4

84.9

84.4

82.8

83.1

82.8

82.8

82.8

82.8

82.8

24

Knitting M/c 7



Cutting M/c

Electric Motor

80

8580

8580

908580

908580

21

2416

2515

101515

15205

5

205

205

25155

40150

Mean

83.1

83.1

85.1

86.2

85.04

Tables 12 : Exposure Records Table of Employee in Solid Minerals crushing mills in Ilorin Metropolis

Noise Source Sound pressure Level

Total duration per wk in hr(Obtained by interview)


LAeq(dB(A))

Electricity Generator

Vibratory Crushing M/c

Vibratory Grinding M/c

Vibratory Milling M/c

1051009590

10510090

10510090

10510090

1.04.012.023.0

8.515.2516.25

9.014.516.5

7.51418.5

801009565

71040045

71040050

63035050

94.8

101.4

101.5

100.2

25

Blower 1 (Vibratory Grinding M/c)

Electric motor 1

Crush Feeding M/c

Sucking M/c

Electric Motor 2

Filling M/c

Blower 2(Filling M/c)

Vibratory Milling M/c 2

Electric Motor 3

Hammer Mill M/c (Hammer Blow)

Milling M/c

959085

959085

1009580

1051009590

959085

959080

959080

959080

959080

10585

1009590

51718

81517

91219

4101016

8.51615.5

151114

61816

818.513.5

8.51912.5

2515

515.519.5

404515

654015

225955

3152508040

704015

125305

45455

65505

70505

198015

10012550

90

91.4

94.6

98.1

91.6

93.2

87.1

91.4

91.6

104.5

94.4

26

Electric Motor 959080

819.512.5

65505

Mean

91.4

94.83

Table 13: Continuous Noise Exposure RecordsExposure Levels in dB(A)

Duration of Exposure in Hours

Operators in the minerals crushing mills

Operators in the soft drink bottling industry

Operators in the Beer brewing & bottling industry

10510095908580

3.43.54.53.93.03.3=21.6

3.03.54.02.52.4=15.4

2.53.03.52.33.1=14.4

Table 14: Impulse Noise Exposure RecordsExposure Levels (Peak) in dB(A)

Estimation number of occurrence per day

Operators in the minerals crushing mills

Operators in the soft drink bottling industry

Operators in the Beer brewing & bottling industry

11511010510095

45286352

=188

50604430

=184

40504547

=182Table 15 shows the computed LAeq (8h) for Minerals crushing mills, soft drink bottling industry and Beer brewing and bottling industry where impulse noise occurred.Table 15 Computed impulse noise exposureIndustry Impulse Noise Exposure

(LAeq (8h)) dB(A)Minerals crushing mills Soft drink bottling industryBeer brewing & bottling industry

110.9106.7105.9

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29

a comparative study of noise pollution levels in ilorin metropolis, nigeria

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