Introduction
... [1-8]. The amount of oxidants and antioxidants in healthy people is always in balance, increasing the concentration of oxidants or decreasing antioxidants will lead to loss of this balance and to oxidative stress [9]. One of the effective factors in upsetting this balance is pollution caused by urban traffic [7, 8]. In 2020, Marianne Geiser et al. investigated inflammation due to oxidative stress in airways susceptible to human aerosols [5]. In 2021, Münzel Thomas et al., by examining the parameters of oxidative stress, found that ambient air pollution increases the risk of cerebrovascular disorders by causing inflammation and oxidative stress [6]. In 2021, Stephanie M. Holm et al. examined the association between traffic-related air pollutants, biomarkers of metabolic dysfunction, oxidative stress, and lung epithelial damage in children [7]. ... [9-16].
Aim (s)
The aim of this study was to compare oxidant factors (nitric oxide (NO), malondialdehyde (MDA)) and antioxidants (total oxidative capacity (TAC), catalase (CAT)) in drivers' blood serum.
Research Type
This study is a prospective cohort study.
Research Society, Place and Time
Male drivers (urban and suburban) who had referred to the occupational medicine of Ghaemshahr city-Mazandaran, Iran between 2019 and 2020 to issue a health card, formed the statistical population of this study.
Sampling Method and Number
As a control group, 45 urban and suburban drivers who were exposed to urban traffic pollution and 45 extra-urban drivers whose traffic route was rural roads and out of traffic and urban pollution, were selected using systematic sampling method.
Used Devices & Materials
Oxidative and antioxidant parameters (NO, MDA, TAC and CAT) were measured in serum blood. Quantitative parameters such as height, weight, glucose level and cholesterol level were also measured by standard methods. A questionnaire was also completed for each person including demographic information and history of cardiac risk factors in the past (hypercholesterolemia, diabetes). The methods used in this study were taken from the book of biochemical experiments of Dr. Amir Hossein Esmaili and also the book Antioxidant and Evaluation of Antioxidant Parameters by the same author. This study was performed in Ahura Lab and Shafa laboratories of Ghaemshahr, Iran. Blood samples were taken from the samples after 12 hours of fasting. Wills method [17] and Hadley and Draper double heat method were used to evaluate the development of lipid peroxidation in the serum of the studied samples and to quantify the amount of MDA. ... [18]. Total antioxidant capacity was measured by ELISA method using ZellBio kit [19]. Determination of catalase activity in samples was also evaluated based on Abie method [20] and slight changes in Luck method [21].
Ethical Permissions
By obtaining written and informed consent from individuals and fully explaining the purpose and method of the investigation, individuals were assured that the information would remain confidential.
Statistical Analysis
The data of the collected samples were encoded and analyzed using SPSS 22 software. T-test was used to compare the means. P <0.05 was considered to calculate the significant level of parameters.
Finding by Text
90 samples with an average of 30 to 60 years participated in this study in which there was a significant difference between age, glucose and cholesterol parameters in the group of urban drivers compared to suburban drivers (p <0.05) but the difference in height and weight parameters was not significant (0.05 0
Main Comparison to the Similar Studies
... [22-24]. Many parameters for the occurrence of oxidative stress such as catalase, superoxide dismutase, glutathione peroxidase, malondialdehyde and total antioxidant capacity are measured among individuals [25, 26]. The results of this study showed that the level of catalase in people exposed to traffic pollutants was lower than the control group. A study of taxi drivers by Brucker et al. showed that the levels of activity of catalase, glutathione peroxidase, and glutathione-s-transferase enzymes in drivers exposed to traffic pollutants were lower compared to control group. [25]. Another study looked at oxidative and nitrous stress levels among 50 bus drivers in Prague, Czech Republic. In this study, a significant increase was observed in the level of oxidative and nitrifying stress markers among bus drivers in comparison with the control group [29]. ... [30, 31]. The results of the present study showed that traffic pollutants increased the amount of malondialdehyde. In a study by Dejmek et al., the effects of traffic pollutants on oxidative stress markers in city bus drivers were investigated. The results increased the level of all 3 markers of oxidative stress including markers of DNA damage; The marker of lipid peroxidation and the level of carbonyl groups of proteins in bus drivers show a significant increase compared to the control group [32]. In this study, serum nitric oxide levels were significantly lower in the group exposed to traffic pollutants. Nitric oxide acts as an anti-inflammatory agent in physiological concentrations and is a toxic substance for invading and infectious microorganisms, and reducing the amount of nitric oxide in people who are exposed to traffic pollutants causes these diseases [33]. On the other hand, in the present study, the total antioxidant capacity in the group exposed to traffic pollutants was significantly lower than the control group. Nazi et al, have reported similar results [34]. Antioxidants are substances that inhibit or delay oxidative damage to a target molecule. In the study, there was a significant reduction in total antioxidant capacity in people exposed to traffic pollutants compared to controls. People exposed to traffic pollutants, including police traffic and urban drivers, are exposed to significant amounts of oxidizing agents in terms of the work environment they interact with. Improving their nutrition is one of the ways to increase antioxidants in this group of people [35]. The cause of high lipid peroxidation in the plasma of individuals exposed to traffic contaminants is enzymatic and non-enzymatic deficiency of the antioxidant defense system. The enzyme catalase plays a very important role in protection against lipid peroxidation, which showed a significant reduction in people who are exposed to traffic pollution.
Limitations
Study limitations included intervention variables that could affect outcomes, for example, driving time, smoking, diabetes and cardiovascular disease, diet, and sleep or wakefulness in drivers were not the same.
Suggestions
It is suggested that the effect of food enrichment in the diet of people exposed to traffic pollution be investigated to compensate for antioxidants and prevent cancer and cardiovascular disease caused by oxidative stress caused by traffic pollution. It is also recommended to evaluate the levels of vitamins E, C and selenium in the blood serum of these people.
Conclusions
The results of this study showed that the mean parameters of nitric oxide, total antioxidant capacity and catalase in the group of drivers exposed to traffic pollutants were lower than the control group, while lipid peroxidation was higher in this group compared to the control group. As a result, traffic pollutants increase the risk of oxidative stress in people exposed to traffic pollutants and can have an adverse effect on their health and the occurrence of oxidative stress-related diseases, including heart disease.
Clinical & Practical Tips in Police Medicine
Highway police forces are exposed to significant amounts of oxidizing agents, which reduces the antioxidant defense system in these people. The antioxidant capacity decreases and the antioxidant balance of the antioxidant changes to oxidative in this people.
Acknowledgments
This study is part of Ms. Leila Tabarestani's dissertation. The authors of this article would like to thank Dr. Younes Mahmoudi, the staff of Ahura Lab and Shafa laboratories, all relevant officials of Ghaemshahr Occupational Medicine Center and Tehran Azad University, for their cooperation in carrying out this research project.
Conflict of Interest
The authors state that there is no conflict of interest in the present study.
Funding Sources
Some parts of this research was done with the financial support of Azad University.

Table 1) Comparison of two groups of people exposed to
 traffic pollution (urban drivers) and far from traffic pollution (suburban drivers)

Figure 1) Comparison of nitric oxide levels in the two groups
 (***significant difference at levels less than 0.001)

Figure 2) Comparison of malondialdehyde levels in the two groups
 (***significant difference at the level of less than 0.001)

Figure 3) Comparison of total antioxidant capacity in the two case groups
 (***significant difference at the level of less than 0.001)



Figure 4) Comparison of catalase activity in the two groups
 (***significant difference at the level of less than 0.001)