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Comparison of Spatio-Temporal Variations of Various Pollutants Levels at Residential, Industrial and Vehicular Sites of Lahore, Pakistan

The entire atmosphere is full of useful constituents present in the air and the environment possesses particulates, flora or fauna and alters the temporal variations [1]. A healthy ambient air is generally made up of 79% nitrogen (N2), 20% oxygen (O2), and 1% fusion of carbon dioxide (CO2), water vapors and little amount of numerous additional gases. [2]. Fresh and sterilized air is regarded as a crucial need for humans and animals, however, unclean atmosphere cause a major risk for the whole world [3]. At present, the human health and healthy environment directly correlates with each other [2,4].


Introduction
The entire atmosphere is full of useful constituents present in the air and the environment possesses particulates, flora or fauna and alters the temporal variations [1]. A healthy ambient air is generally made up of 79% nitrogen (N 2 ), 20% oxygen (O 2 ), and 1% fusion of carbon dioxide (CO 2 ), water vapors and little amount of numerous additional gases. [2].
Fresh and sterilized air is regarded as a crucial need for humans and animals, however, unclean atmosphere cause a major risk for the whole world [3]. At present, the human health and healthy environment directly correlates with each other [2,4].
A review of the ambient air quality is very necessary because it completely effects on individual well-being [5,6]. The present atmosphere contains air, water and ground pollution. About 76% of the entire particulate matters result in air pollution as a whole. There are several main reasons of worst urban air quality such as bad quality of fuel, vast number of old vehicles, insufficient assessment and conservation plans [7].
Due to the presence of contaminants in the environment disturbs the weather conditions. Increase in contaminant's level reaches the temperature range at dangerous zone in urban areas [7,8]. The harmful particles present in the environment and emissions arise from contaminants fluctuate with the time period disturb the natural ecosystem [9,10]. Destruction of the environment by natural or human induced processes is a dilemma and there is a need to cope with challenges of the present world. The main necessities for every air cleanup procedure are the elimination of the filthy smell and lethal gases of harmful particles [11]. Air pollutants level is increasing day by day [2].
The atmosphere is full of those elements or pollutants that emits during manufacturing or destruction of buildings which is clearly visible [12]. Particulate matter (PM 2.5 ), Nitrogen dioxide (NO 2 ), Sulphur dioxide (SO 2 ) and Carbon monoxide (CO) are the harmful pollutants which deteriorates the environment [7,13]. These particles interrelate to develop another secondary air pollutant for example, Ozone (O 3 ) which is extremely reactive and occur naturally in air. PM 2.5 particles are made up with a composite jumble of living and non-living materials (solid, liquid) present in the atmosphere. The main constituents of PM 2.5 are sodium chloride, black carbon, mineral dust and water. The harmful elements are the one with 10 μm thick or less easily enter and stay within the lungs. The long-lasting contact with contaminants resides in the atmosphere linked with health effects. Sources of PM 2.5 comprise incineration, industrial units, destruction, farming actions and automobiles. After a while, sufficient intake of PM 2.5 boosts up the possibility of chronic respiratory syndromes [14]. PM 2.5 contaminant becomes lethal when it comes into contact with additional contaminants such as NO 2 and O 3 [15]. NO 2 is a rosy-brunette gas with a pungent smell. The crucial causes of this gas are automobiles and their emissions. Heavy inhalation diminishes vision power and amplifies the danger of pulmonary diseases. Source of NO 2 is due to the burning of fossil fuels. It evolves from group of oxides of nitrogen (NO x ). NO x merge with additional amalgams such as ammonia and humidity to create minute particles able to infiltrate into the lungs [14]. SO 2 is colorless, disgusting and have bitter smell. Source of SO 2 is the ignition of fuels (e.g., oil and coal). Sulphur dioxide is important and prevalent contaminant enters in lungs and results in respiratory disease such as Chronic Obstructive Pulmonary Disease (COPD) [16]. It triggers the inflammation in lung tissues and spoils health of living beings. CO is neutral, colorless gas produce from the partial ignition of fuels. Consequently, the dominant causes of CO nowadays are automobiles. Infiltration of this gas lessens the quantity of O 2 in the blood vessels and elevated levels results in headaches, faintness, coma and collapse [14]. NO 2 combines with hazardous substances and high beam rays to generate ground-stage O 3 level [15]. Ozone (O 3 ) is a minor contaminant arises when sunbeams bring about photochemical reactions containing NO x and volatile organic compounds. Increase in levels is likely to rise in the afternoon. It affects like inflammation of eyes, increase risk of respiratory diseases and ultimate destruction of plants and animals [14]. Internationally, atmospheric contamination was most important ecological matter which disturbed pulmonary system of human beings [17].
Northern Italy has among the top dirtiest regions of Europe. The appropriate and instant socioeconomic growth, China has been facing critical atmospheric pollution matters [17,18]. The goal of the study is to assess the degree of air pollution in the surrounding areas that have been identified to monitor the air pollutants parameters, i.e., PM 2.5, NO 2 , SO 2 , CO and O 3 which influence ambient air quality also, find the correlation between various air pollutants and showed comparison among different contaminants at various sites.

Plan of work
This chapter contains information about how this research work has been conducted in assessment of ambient air quality. It further highlights all the methods employed to calculate air quality and the ways data collected for accounting all the air pollutants. The present study was designed to accomplish an assessment of the air pollutants parameters to monitor air quality which led to severe health impacts and compared the monitored values with the National Ambient Air Quality Standards of five most important pollutants like PM 2.5 , NO 2 , SO 2 , CO and O 3 .
The year comprised of four seasons to analyze the seasonal and temporal differences: Winter, spring, summer and autumn. The weather of Lahore such as summer is scorching and damp whereas winter is cool and dry. Similarly, spring is less hot, temperature amplifies steadily and flowers blossom and autumn is neither hot nor cold because temperature decreases slowly. The winter is comprised the months of January, February, December, spring begun from March, April, May, summer started from June, July, August and autumn season come in the months of September, October and November as per local meteorological conditions.

Sampling area
The study zone consists of three different sites from where air quality data has been monitored such as residential, industrial and vehicular sites. The residential is extended between 31°30'42.49''N latitude and 74°20'08.76''E longitude elevated at about 704 ft nearby National Hockey Qaddafi Stadium, Ferozpur Road Lahore. Sampling apparatus is carried out during air quality monitoring. Low Volume Air Sampler IMD-5IMP (SIBATA HV-1000F) would be used to check the concentration (µg/m 3 ) levels of air pollutants like PM 2.5 at designated sites. The NO 2, SO 2 and O 3 was calculated with the help of portable detector BW Gas Alert NO 2 extreme, BW Gas Alert SO 2 extreme, and BW Gas Alert O 3 extreme respectively. CO was collected with the help of portable instrument Neotronics Impulse XT. All the devices were placed at location for obtaining the maximum level of PM 2.5 , NO 2 , SO 2 , CO and O 3 in the air (Figures 1-4).
This Figure 2 shows the map of desired sampling sites in Lahore Punjab, Pakistan.

Data analysis
The study involved is descriptive and quantitative analysis.  Descriptive analysis is used to depict and elucidate the analysis of both tables and figures. Quantitative analysis brought out by means of IBM SPSS 24.0 version statistical software. Correlation analysis is to get the relationship (correlation) between air pollutants. The data obtained were presented in tabular form. Likewise, the obtained results were compared with National Ambient Air Quality Standards limit to testify the levels of contaminants.

Results and Discussion
This portion assesses and elaborates the findings of the current research. The results were dependent on analysis of air quality parameters and their correlation analysis through SPSS 24.0 software. They were used to determine the concentration of particular five respective pollutants such as PM 2.5 (µg/m 3 ), NO 2 (µg/m 3 ), SO 2 (µg/m 3 ), CO (µg/m 3 ) and O 3 (µg/m 3 ).

Concentration (µg/m 3 ) levels of air pollutants at industrial site
The multiple seasonal readings in recent study period of six years were carried out to check out the air pollutants levels reside in the atmosphere. At designated sites, multiple readings of each pollutant were recorded in different seasons. The data was represented in the form of simple line-bar charts/graphs. In previous studies, the mean concentration of PM 2.5 has obvious seasonal variation characteristics, the lowest value in summer and the higher value in winter and autumn. The seasonal characteristics with high concentration in winter and autumn but low in summer mainly could be attributed to the stable atmosphere in Changsha in autumn and winter [19]. Air pollution levels are the highest in the winter and the lowest in the summer observed in 32 major cities of China [20].
Photochemical associations of pollutants (NO x and VOCs) are mainly because of the greater intensity of sunbeams led to elevated O 3 concentration levels [21]. Numerous reports from Brazil indicated that in those zones where atmospheric pollution level was led by sugar cane incineration directly correlated with PM 2.5 concentrations [22].

Correlation within pollutants
Five major particular pollutants that were need to be monitored and correlated within those specific pollutants because one specific pollutant may increase or harm the other pollutant/environment. Significant association was found within pollutants at three different sites (residential, industrial and vehicular sites). The results suggested that there was strong positive bivariate correlation being observed between each pair of pollutants (PM 2.5 , NO 2 , SO 2 , CO and O 3 with p<0.01 or p<0.05) in Tables 1-3.
The increased concentration levels of pollutants (PM 2.5 , NO 2 ) being observed at vehicular site on the other hand elevated concentration level of pollutants (SO, CO, O 3 ) was seen at residential site. There was a study of Shanghai, China evaluate correlation coefficients which is quite similar to this study. Several current findings indicated that there was a strong connection between specific air contaminants [19].
All the pollutants (PM 2.5 , NO 2 , SO 2 , CO and O 3 depicted positive correlation within the pollutants at all sites (a, b and c) except PM 2.5 and NO 2 showed negative bivariate correlation with CO in the Table 3.

Conclusion
Most of the pollutants (PM 2.5 , NO 2 and O 3 ) were found to increase in winter season except SO 2 and CO which showed high concentration in spring and autumn seasons respectively. The questionnaire survey results have been shown that the health status was good of those people that were not living nearby industrial area. Kendall's tau-c test is applied on questionnaire results shows that all the factors indicated a significant association with health facilities, health status, air quality and the trends of air pollution level over last 10 years. Air purifiers are also need to be introduced in the environment which may help to reduce pollution all over the Pakistan. Use of Public Transportation, buy energy efficient vehicles, make use of Solar Energy, quit smoking which might purify the air. Grow Own Fruits and Vegetables in home and banned on cutting down of forests would be a great way to stop air pollution. It will be a major challenge to reduce the negative environmental effects and environmental risk factors can be mitigated, leading to improved health outcomes in patients with pulmonary diseases. By eliminating the source of the problem the level of pollution can be controlled. There should a need of preventive measures to be performed for safeguarding the health of the humans.