Assessment of the level of noise and chemical air pollution in two distinct urban areas

In the paper are presented the results of tests on the evaluation of the level of noise and chemical air pollution in two distinct urban areas: an industrial area and an area characterized by heavy road traffic, with a focus on the novelty elements introduced by the regulations in force on the measurement and management of the level of ambient and industrial noise by periodically developing specific noise maps. The results of direct tests and noise maps developed in the case of the studied areas indicated higher values of the indicators measured near the road artery compared to the other measuring points, highlighting the influence of vegetation in urban areas to reduce noise levels and reduce air pollution.


INTRODUCTION
The environment is an essential element of human existence and is the result of the interference of natural elements with elements created by human activity. Ensuring a proper quality of the environment, protecting it as a necessity of survival and progress, is a matter of major interest and certain topicality [1]. Industrial development policy in recent years has aimed at transforming the industrial economy into an economy based on sustainable development interest in the protection of the environment in general and air in particular; special attention is paid to noise pollution in urban areas, due mainly to heavy road traffic and activities carried out in industrial areas [2][3][4][5]. Noise is a risk factor with harmful effects on the human body, which can lead to disorders not only of the hearing aid but also of other organs with effects on labor productivity but also on the general health of people [6][7][8][9][10][11][12] All input values affecting the emission level of a source shall be determined at least with the accuracy corresponding to the uncertainty in the level of the source emissions [13]. To calculate the uncertainty of measuring the noise level in the industrial zone, it is necessary to estimate the uncertainty of the measurement conditions. Thus, the determinations are made at distances small enough from the sources so that the variations in the sound pressure level are independent of the meteorological parameters according to equation 2: where Lmi is the measured value representing a typical cycle of operation, expressed in decibels (dB), is the arithmetic mean of all Lmi , expressed in decibels (dB), and n is the total number of all independent measurements. The total uncertainty is given by the following equation: where: is the sensitivity coefficient calculated for the measured noise level to be determined by the equation: is the sensitivity coefficient calculated for the measured size of the residual noise to be determined with the equation: The uncertainty calculation also involves determinations of the residual noise level, measurements made at a distance large enough to eliminate or undetected the noise emitted by the tested sources [16]. For the noise level determined in the area with heavy traffic, the equivalent leq noise level is determined by the direct counting of all vehicles (regardless of their type) passing through the vicinity of the measuring point. The number of vehicles allows the calculation of standard uncertainty: (dB) (6) where n is the number of vehicles; C = 10 for combined traffic as is the case with this study.
In this paper are presented the results of tests on the evaluation of the level of noise and chemical air pollution in two distinct urban areas: an industrial area and an area characterized by heavy road traffic, with a focus on the novelty elements introduced by the regulations in force on the measurement and management of ambient and industrial noise levels by periodically developing specific noise maps.

EXPERIMENTAL PART
Location Figure 1 shows the two areas studied and the points at which the measurements were made. It should be added that for noise measurements and acoustic map making, a higher number of measuring points were made both near the main sources and at two distances of 50 m each as required by the noise mapping program. For pollutants determined at the emissions, 4 measuring points were established and the determinations were made under the standards of the method in force [19][20][21]. For the measurement of NO2, SO2, and CO at the emissions, the measuring equipment was placed in the points shown in Figure 1 as follows: for the industrial zone at the limit of industrial property and the area with heavy road traffic (intersection) two points near the street and the other two at a distance of about 50 m from the street in the area with vegetation. The tests were carried out at a maximum activity time interval for the areas studied. Figure 2 shows the equipment with which the measurements were carried out: for pollutants in the surrounding air CO, NO2 si SO2 -automatic analyzers Horiba (Fig. 2a), which perform continuous measurements by the following methods: spectrometry in IR non-dispersive for CO, fluorescent for SO2 and chemiluminescence for NO2; for the noise level was used Sonometer Light Brüel & Kjaer 2250 (Fig. 2b)  Noise level measurements were made over 10 minutes for each point and results were made to measurements representing the noise level in (dB) over the frequency range between 31.5 Hz and 8 kHz was used to make the noise map for the two areas studied. The values obtained were compared with the limits presented in the current legislation: SR 10009:2017 for the noise level, for the pollutants measured at the emissions: NO2 si SO2 (1-hour measurements) -Law 104/2011; CO (30-minutes measurements) -STAS 12574-87 [22][23][24]. The results of noise measurements were used to make noise maps for both sites. For noise level mapping, the software was used as a software PREDICTOR 7810 Version 6.1 from Brüel & Kjaer. Figure 3 shows graphically the values determined for the noise level in the industrial zone (Fig. 1a) and in Figure 4 the values of the noise level measured at the points established for the characterization of noise pollution in the urban area with heavy road traffic (Fig. 1b).

Fig. 3. Noise measurement graphs depending on the frequency at the 4 points
It is found that the values recorded in these points are: Point The conditions in which the measurements were performed, the peak period of the urban traffic, determined the obtaining of more values for points 1 and 2 because the measurements were performed near the street and points 3 and 4 are lower values that slightly exceed the limit. from the legislation for values of the noise level near the house. Figure 5 shows the noise map for the industrial area and Figure 6 shows the values calculated by the noise map software used, values of the noise level at the edge of the studied area. Thus, it is observed that at the edges of the studied area, the noise level reaches values between 60 -65 dB. The limit for industrial premises and spaces with activities assimilated to industrial activities is 65 dB thus, the values at the limit of the studied area fall within the limits provided in the legislation [22]. For the area with heavy road traffic, Figure 7 shows the noise map and Figure 8 shows the values calculated by the noise map software used, values of the noise level at the edge of the studied area. Higher values are observed for the pollutants determined at immissions for the second case, especially at points 1 and 2 located near the street where the noise level is also higher (Fig.  10). Points 3 and 4 show lower values for both NO2, SO2, and CO pollutants and the noise level due to the attenuation caused by the vegetation curtain. Fig. 10. Graphs of CO, NO2, and SO2 measurements in the area with heavy road traffic

CONCLUSIONS
The results of tests performed to assess the level of noise and chemical pollution with CO, NO2, and SO2 highlight the following aspects: In the case of the industrial area, points 3 and 4 present higher values for the noise level 64.1 dB, 65.1 dB because it is in the vicinity of noise sources (industrial fans). From air pollution, higher concentrations were obtained in point 1, located in the wind direction, values that fall within the limits imposed by the legislation.
In the case of the studied urban area with heavy road traffic, higher values were obtained both for the noise level and the chemical pollutants in points 1 and 2 points that are placed near the street. For the other measurement points, the values are lower due to the vegetation area that attenuates both the noise level and the concentration of CO, NO2, and SO2 in the ambient air. It is recommended in this situation to increase the areas with vegetation in urban areas to reduce both the noise level and the chemical pollution of the air with compounds specific to traffic emissions. For the industrial area, the placement of attenuators or sound-absorbing barriers in the vicinity of noise emitting sources will reduce the level of noise pollution in the workplace and in the vicinity of industrial units.

ACKNOWLEDGEMENTS
The tests were carried out in the Competitiveness Operational Program project nr. 55/05.09.2016 "Promoting, identifying and implementing partnerships for the transfer of knowledge in the field of industrial ecology", ID_P_40_300, cod SMIS 105581, Subsidiary contract nr. 2142/12.02.2019.