Evaluation of Equivalent Noise Levels across Some Commercial Areas of Warri and Benin Metropolis in Nigeria

: Globalisation has given rise to an increase in the amount of noise generated around us, such that man has adjusted to this increment without considering the possible risks associated with it. This study aims to measure the equivalent noise level in eighteen (18) locations in some commercial areas of Warri and Benin Metropolis in Nigeria using a noise level metre (Model: CEL-231). The assessment was done twice daily, during the day and at night. The results obtained revealed that the daytime equivalent noise level of both cities ranged from 48–68, 78–102 dBA for minimum and maximum noise levels, while the nighttime equivalent noise level ranged from 39–59, 59–83 dBA for minimum and maximum levels, respectively. It was observed that the daytime noise level values in some locations for both cities were higher than the nighttime values and also higher than the recommended standard noise quality description for daytime and nighttime duration as recommended by the World Health Organization (WHO) and some existing literature in Nigeria and across the globe. The reason for this noise level elevation is due to the activities of automobiles and tricycles plying the road incessantly, and again, these are major industrial cities with a lot of activities during the daytime. However, it can be recommended that those whose daily activities confine them to areas with unhealthy noise levels ensure at least 10 hours of recovery time in areas where the sound level is less than 65 dBA and also encourage the planting of trees in this vicinity.

Noise pollution is a pervasive issue in commercial cities worldwide.With rapid urbanisation and industrialisation, the constant buzz of traffic, construction, and commercial activities has become an unavoidable part of urban life.Excessive noise levels disturb the tranquilly of urban dwellers and cause detrimental effects on their physical and mental health.As such, it is crucial to delve into the causes and consequences of noise pollution in commercial cities to find solutions.(Bilewu et al., 2019;Mansouri et al., 2006;Amoatey et al., 2020;Anomoharan, 2013).
However, transportation or road noise is the leading source of noise in many cities (Yilmaz and Ozer, 2005).Blake (2006) asserted that noise is an unwelcome, unwanted sound that emerges from human activity.Sound pressure is used to assess the study of sound: its production, transmission, and reception.The environment and the noise source's power output affect the sound pressure level.The ear's incredible capacity to process sounds is astounding.However, sound becomes an issue when it obstructs our ability to read, work, or engage in leisure activities.
Sound is important in aspects of communication and to enjoy drama and musical performances.Some loud sounds are signals that alert us to an oncoming potential hazard ahead, such as an aeroplane about to land at the airport.Changes in sound pressure are responded to by the human hearing mechanism in a relative rather than absolute manner.This is why the sound pressure level is measured using a logarithmic scale known as the decibel (dB).The threshold of hearing, which corresponds to 0 dB, is the weakest sound that the human ear can detect.The threshold of pain, on the other hand, is defined as the level of sound pressure that causes pain in the ear and corresponds to 120 dB.A 3 dB variation in sound intensity is just enough to make such a difference perceptible.Nonetheless, one can perceive a 10 dB rise as twice the sound's volume.Two weighting networks, the A and C networks, are used in sound measuring.However, for environmental applications, the measurement is conducted using an A-weighted scale (dBA), which measures sound levels like those of the human ear.Noise pollution has been identified as a serious problem facing the world today.According to the WHO, noise is a hazardous substance that harms both human health and the environment.People in Nigeria, on the other hand, pay little attention to the significance of noise pollution and its harmful environmental implications.This is not the situation in other nations where adequate measures have been put in place to control and regulate this hazard (Anomohanran et al., 2008;Rafal and Emil, 2023).In every human activity, there is always an interference of noise; hence, one can categorise noise as an occupation (workplace noise) or environmental noise, which involves noise in all other areas, be they community, residential, or domestic (traffic, playground, sports, and music).Noise pollution is an environmental problem that constitutes a nuisance, and it has not been widely recognised in our growing society but has gained recognition in developed countries (Mangalekar et al., 2012).Sources of environmental noise pollution in the urban locality are road vehicles, tricycles, heavy-duty trucks, and motorcycles (Usikalu and Kolawole, 2018).The World Health Organisation (WHO, 2006) noted that exposure to incessant noise at night leads to selfreported sleep disturbances and induced sleep, classified as health problems or challenges.It is evident in the literature that noise pollution disturbs sleep, causes fatigue and accidents, and reduces performance.Traffic noise pollution affects those living around road junctions in urban cities.As a result of the ever-present exposure to noise in these study environments, people lose their hearing ability, decreased human performance and action, put stress on the nervous system, annoyance, developed hypertension, headaches, and increased blood pressure (Naish et al., 2012;Esi et al., 2015;Passchier-Vermeer and Asscher, 2000).The World Health Organization (WHO) Guidelines Development Group advises that noise levels from road traffic be kept at 53 decibels (dB).In addition, for nighttime noise exposure, it recommends decreasing noise levels caused by road traffic to less than 45 dB.In the Nigerian cities of Warri and Benin Metropolis, determining the levels of noise pollution is of utmost importance.
With rapid urbanization and industrialization, these cities have experienced a surge in population and economic activities, resulting in increased noise pollution.Understanding the extent of noise pollution in these commercial cities is crucial for developing effective strategies to mitigate its negative impacts on the health and well-being of residents.Hence, the objective of this paper is to evaluate the Equivalent Noise Levels across Some Commercial Areas of Warri and Benin Metropolis in Nigeria

MATERIALS AND METHOD
Study area: The study areas (Warri and Benin City) are cosmopolitan cities from the medieval located in the southern region of Nigeria, usually named the Niger Delta Area.The sampled locations and their geographical locations are presented in Tables 2 and 3 below.The study locations have a population of 1,397,646 (NPC, 2006).The occupation of the people in this region was mainly agriculture and craft before the establishment of numerous multinational companies and industries such as the Warri refinery and petrochemical industry and the Nigeria port authority.These companies came into being as a result of the natural resources (oil) found in this region, and this has equally increased the population of individuals residing in these areas and automatically turned into a commercial, industrial, and metropolitan city based on the influx of people seeking white collar jobs.

Measurement of noise level:
The study was carried out using a portable sound level metre with model number CEL 231.This metre is used to determine the exposure level to noise in our environment.The sound metre reading starts at 20 decibels and not zero (0) because no environment is 100% free from noise and one cannot observe total quietness in an area.The ambient noise level was monitored and measured using the metre within the hour (8:00 a.m.-6:00 p.m.) during the daytime (LD) and the nighttime (LN) (10:00 p.m.-6:00 a.m.).The measurement was performed according to the instructions provided by Maiti in 2003.Basic safety measures were taken by choosing an acceptable and suitable distance from the source of sound to allow for sound resonance and echo.According to noise guidelines (2000), as updated in 2010, readings were taken and recorded every ten (10) seconds for six minutes at each point of measurement in the area (during the day and night).

RESULTS AND DISCUSSION
The minimum and maximum daytime and nighttime noise levels in some selected locations in two prominent cities in the Niger Delta region of the southern part of Nigeria, together with their geographical locations, have been presented in Tables 1 -4.The time between 8:00 a.m. and 6:00 p.m. is referred to as daytime, and the hours between 10:00 p.m. and 6:00 a.m. are known as nighttime.The measured ambient sound levels were compared to values from other published sources, such as the Environmental Protection Act of 1986 and the CPCB (Triparthy, 1999), as well as international norms.The noise pollution controls and regulations laws from 2000 have established a standard for the environmental noise pollution level, which serves as a standard and limit for monitoring.Table 1 shows the ambient air quality criteria for noise for all four zones.The day-time equivalent noise levels for both cities ranged from 48 to 68, 78 to 102 dBA for minimum and maximum noise levels, and also from 39 to 59 and 59 to 83 dBA for minimum and maximum noise levels as shown in Tables 3 and 4 respectively.From Tables 3  and 4, Oba market, the ring road, and Igbudu market all had elevated noise levels (95,92,and 93 dBA).This is also characterised by the presence of commercial and business activity in these areas, which could have increased noise levels.The quality of the daytime maximum noise level was observed to be above the typical noise quality description for daytime and nighttime at several locations in Warri and Benin.
Comparing the obtained results with the standard noise quality description for daytime and nighttime duration values as stated in Table 5, it is clear that New Benin, with a daytime equivalent noise level of 102 dBA has the greatest noise level which falls in the not allowed region following the criteria in Table 5.This highly Tables 6 and 7 give the quality of the level of noise generated in the study areas, ranging from good quality to not allowed, but the majority of the locations were within the unsatisfactory range.The locations (Okere Market, Avenue by Estate, Igbudu Market, Siluko Road, Akpakpava Road) fall within the satisfactory limit for nighttime noise levels of 62, 65, 63, 59 and 60 dBA, respectively.
The map depicting the daytime and nighttime noise levels in the studied locations is as shown in Figures 1-4.The figures below will serve as a guide for the populace to ascertain if the area is suitable to work and live in, considering the health implications.

Fig 1 :
Fig 1: Daytime noise map for Benin

Table 1
Noise standards for ambient noise level

Table 1 :
Sampled areas and their geographical locations in Warri

Table 2 :
Sampled areas and their geographical locations in Benin

Table 3 :
Measured Mean Values of Noise Level in Some Selected

Table 4 :
Measured Mean Values of Noise Level in Some Selected