1.0 Introduction

Air pollution is the largest environmental health risk, contributing to millions of premature deaths annually [12, 16]. Given its far-reaching effects, air quality has become a focal point in discussions on climate change, public health, and sustainable development. Studies have shown that exposure to air pollutants, particularly fine particulate matter, can negatively affect cognitive function [14], increase the risk of neurological disorders such as dementia and Alzheimer’s disease [19] and increase the risk of neurodegenerative diseases, and Parkinson's disease [14, 15, 20]. Air Pollutants may induce oxidative stress and inflammation in the brain, leading to long-term cognitive decline [18]. Auto-mechanic village is a portion of land where repair and services of vehicles is done [3-5]. Services such as serving of vehicle engines, repair of fuel tanks, repair or charging of batteries, repair of brake systems, repair of clutch system and overhauling of vehicle engines are been carried out [3]. Its environment has a characteristic black color, littered with pieces of metal scraps from cars and contaminated with spent engine oil [4]. It has been recognized that activities in auto-mechanical workshops increase air pollution which has short and long-term effects on lung health [6, 12]. In Nigeria, most of the artisans responsible for vehicle maintenance and tire repair are working in the informal sector of the economy [1]. Their workshops are scattered all over the major cities. In providing their services, these workers carry out tasks like draining fuel or handling dangerous substances that regularly expose them to dust, lead, used auto lubricants, exhaust fumes, or petroleum products [11]. Several studies among car repair workers demonstrated that the exposure to these hazardous substances was associated with an increased prevalence of health problems, such as cardiovascular, urinary, brain, respiratory, and skin diseases [1,10]. The repair and maintenance activities generate a range of pollutants, especially from processes like engine testing, welding, and spray painting. Vehicle emissions from testing and tuning engines release carbon monoxide (CO), oxides of nitrogen (NO_x), and particulate matter (PM) into the atmosphere, which are known contributors to air pollution and are harmful to respiratory health [19, 22]. Spray painting releases volatile organic compounds (VOCs), which contribute to smog formation and pose respiratory hazards to workers and nearby residents [22]. In addition to these pollutants, auto-mechanic villages often use unregulated waste disposal methods, which can worsen pollution levels. For instance, oil spillage, improperly disposed batteries, and burning of used tires release harmful chemicals that can seep into the air, soil, and water [12, 22].

Auto-mechanic workshops are known for their exposure to various physical and chemical hazards. These hazards include exhaust fumes, dust, and chemical spills, which can lead to severe health issues such as respiratory problems and skin diseases [15]. These hazards in auto-mechanic villages also include high levels of particulate matter and gases such as carbon monoxide and volatile organic compounds (VOCs) [4]. These environmental conditions pose serious health risks, yet the existing research is sparse and lacks localized data. In Nigeria, where many auto-mechanic workshops operate in informal settings, traditional industrial safety standards may not be adequately applied or enforced, exacerbating the risks [2, 11]. Despite the known risks, there is a significant lack of research on the specific air quality conditions in these settings, particularly in Ibadan's auto-mechanic villages.

2.0 Methods

Cross-sectional survey design was adopted, integrating both quantitative (structured questionnaire) and air quality measurement. Air quality monitor (VT9IN1 MODEL) was used to measure air pollutant levels, including particulate matter (PM_2.5 and PM₁₀), carbon monoxide (CO), total volatile organic compounds (VOCs), formaldehyde, temperature, and relative humidity.  Measurements were taken at different times of the day, morning, afternoon and evening.

2.1 Study population

The study was conducted at the Samonda Auto-Mechanic Village, located in Ibadan, Oyo State, Nigeria. Ibadan is a capital of Oyo state, the largest city in West Africa and second largest in Africa. The target population consisted of consented artisans operating within the auto-mechanic village. These include automobile mechanics, welders, spray painters, electricians and apprentices under their tutelage.

2.2 Study Area

Samonda Auto-mechanic Village is situated in Ibadan North Local Government Area, Oyo State, Nigeria. Geographical Coordinates is between Latitude 7.3962° N, Longitude 3.9167° E. The village is nestled within the Samonda neighborhood, approximately 5 kilometers north of Ibadan city center. The village spans around 10 hectares of land. Estimated population is between 100-200 workers of age range 18-60 years.   This village is a hub for vehicle maintenance and repairs, hosting numerous artisans engaged in various trades, including automobile mechanics, welders, spray painters, electricians, and other auxiliary workers.  The village comprises workshops and open spaces where artisans perform tasks ranging from engine repairs to bodywork, making it a suitable location for assessing air quality and the perception of personal protective equipment (PPE) use among workers. Its high concentration of artisans and industrial activities makes it a suitable site for studying occupational exposure and air quality concerns.

Map showing study area - Samonda

2.3 Sampling Technique

A portable air quality detector was used to measure levels of air pollutants, including PM_2.5, PM₁₀, CO₂, CO, total volatile organic compounds, formaldehyde, temperature, and relative humidity. Measurements were taken at eight locations at designated times (morning, afternoon, evening) to capture spatial and temporal variations in air quality for seven days, air sample for each location at 40m distance apart was taken morning (9am), afternoon (1pm) and evening (4pm). Geographic positioning system (GPS) was used for location positioning and coordinates. The air quality meter was positioned at a height of 1.5 meters, approximating the breathing zone of workers.

2.4 Data Analysis

Analysis of Variance (ANOVA) and Duncan Range Multiple Test was used determine the statistical significance of the data and the significant difference   across locations and times of the day. Results were compared to permissible exposure limits set by Occupational safety and health administration (OSHA).

2.5 Ethical Considerations

Ethical approval was obtained from the UI/UCH Health Research Ethics committee at UCH with IRB number 25/0062. Informed consent was secured from all participants prior to data collection. For air quality monitoring, no personal identifiers were collected, and the process adhered to all local regulations regarding environmental sampling

3.0 Results and Discussion

3.1 Air Quality Measurement

The atmospheric temperature recorded across different sampled locations within the auto-mechanic village showed mean values that were higher than OSHA standards (Fig 1). This suggests that the working environment in the area is warmer than recommended, which could contribute to worker discomfort, dehydration, and reduced productivity. The presence of heat-generating activities, vehicular emissions, and lack of shade may be responsible for these elevated temperatures. The concentration of formaldehyde (HCHO) and total volatile organic compounds (TVOCs) was measured at multiple locations but lower than the standard (fig 4). PM_2.5 levels were higher than OSHA standards, whereas PM₁₀ levels were lower as indicated in figure 2. Elevated PM_2.5 concentrations are concerning because these fine particles can penetrate deep into the lungs, leading to respiratory diseases and cardiovascular complications. The high levels may be attributed to combustion engines, welding, tire burning, and unpaved road dust. Measurements of carbon dioxide (CO₂) revealed that concentrations was higher than OSHA standards (fig 3). High CO₂ levels could indicate poor ventilation and can contribute to fatigue, dizziness, and reduced cognitive function. CO₂ emissions are likely due to vehicular emissions, fuel combustion, and inadequate air circulation in workspaces. The results indicate that temperature, PM2.5, and CO₂ levels in all sampled locations exceeded OSHA standards significantly. However, relative humidity, formaldehyde, TVOCs, and PM10, were generally lower than OSHA's permissible limits. The significant differences (P<0.05) suggest air pollution concerns in Samonda Auto-Mechanic Village, particularly in PM_2.5 and CO₂ levels, which could pose health risks to workers and residents in the area. The various air quality parameters measured from the auto-mechanic village is presented in table 2.

Fig 1:  Temperature across the eight locations

Figure 2: Particulate Matters across the eight locations

Fig 3: Level of Carbon-dioxide across the eight locations

Fig 4: Formaldehyde and Total Volatile Organic Carbon across the eight locations

3.2 Perceived Health Impacts of Air Pollution on Respondents

Despite generally positive self-reported health, many respondents experience occasional respiratory issues and other symptoms linked to air pollution. Most recognize the impact of air pollutants on health and see PPE as a protective measure. Majority of respondents (74.2%) rated their overall health as "very good," while 24.2% considered it "good," and only 1.5% rated it as "fair." Despite this positive self-assessment, 97.7% believed that air pollution could affect their health, indicating a strong awareness of its potential risks. Although most respondents considered their health good, respiratory issues were still common. While only 2.3% experienced symptoms daily and 3.0% often, a significant 59.1% reported occasional respiratory problems, and 35.6% experienced them rarely. These findings suggest that air pollution may have periodic but noticeable health effects on workers. Headaches were the most frequently reported symptom, affecting 62.9% of respondents. Other common issues included coughing (39.4%), catarrh (36.4%), eye irritation (11.4%), skin rashes (10.6%), and fatigue (9.1%). Breathing difficulties were reported by 5.3% of respondents, indicating that while severe respiratory problems were less frequent, air pollution still contributed to discomfort and minor health issues. Most respondents (93.2%) experienced symptoms "once in a while," while only 1.5% reported them occurring daily or weekly. This suggests that although air pollution impacts health, its effects may not be constant but rather triggered by specific conditions or prolonged exposure. A strong majority of respondents believed that PPE use could reduce health risks associated with their work. Specifically, 56.8% strongly agreed, and 40.2% agreed, while only 3% disagreed. This indicates widespread recognition of PPE as an effective measure in minimizing workplace health hazards.

Table 1: Perceived Health Impacts of Air Pollutants on Respondents

3.3 The Relationship between Perceived Air Quality and Workers’ Health Symptoms in  Samonda Auto-Mechanic Village

Table 3 presents the correlation analysis to determine the association between perceived air quality and various health outcomes, including respiratory issues, coughing, breathing difficulties, eye irritation, skin rashes, catarrh, headaches, and fatigue. Respiratory issues showed a weak correlation with air quality (r = 0.139), indicating a minor relationship while coughing had a significant positive correlation with air quality (r = 0.195, p < 0.05), suggesting that workers who perceived poorer air quality were more likely to experience coughing. Breathing difficulties did not show a significant direct correlation with air quality (r = 0.085), but they were significantly associated with respiratory issues (r = 0.212, p < 0.05) and coughing (r = 0.224, p < 0.01). Eye irritation showed no significant correlation with air quality (r = 0.080), though it was associated with respiratory issues (r = 0.272, p < 0.01) and coughing (r = 0.200, p < 0.05). Skin rashes had a strong positive correlation with air quality (r = 0.242, p < 0.01), implying that workers perceiving poor air quality were more likely to experience skin problems. Skin rashes were also correlated with respiratory issues (r = 0.231, p < 0.05). Catarrh showed a weak negative correlation with air quality (r = -0.023), but it was significantly associated with respiratory issues (r = 0.211, p < 0.05) and coughing (r = 0.293, p < 0.01). Headaches had no significant correlation with air quality (r = -0.076), but a negative relationship was found between headaches and coughing (r = -0.215, p < 0.05) as well as breathing difficulties (r = -0.238, p < 0.01). Fatigue showed a weak positive correlation with air quality (r = 0.138), but it had significant associations with respiratory issues (r = 0.182, p < 0.05), coughing (r = 0.230, p < 0.05), and eye irritation (r = 0.219, p < 0.05).Significant relationships were observed between air quality and certain health symptoms. Specifically, coughing (r = 0.195, p < 0.05) and skin rashes (r = 0.242, p < 0.01) showed a positive correlation with air quality perception, indicating that workers who perceived poor air quality were more likely to experience these symptoms. Respiratory issues were linked to multiple health symptoms. Workers experiencing respiratory problems were also more likely to suffer from breathing difficulties, eye irritation, catarrh, and fatigue. Headaches and fatigue were indirectly associated with air quality through their relationships with other symptoms. While headaches did not correlate directly with air quality, they showed negative relationships with coughing and breathing difficulties.

Table 2: Air Pollutant from Sampled Locations at Auto-mechanics Village at Samonda

Key: Loc. – Sampled Location, OSHA – Occupational Safety and Health Administration, CO – Carbon-monoxide, CO₂ – Carbon-dioxide.

*P value – Significant (P<0.05). ^abMean±SD = Significantly different (P<0.05) down the column.

Findings:  Mean values recorded for Temperature and PM_2.5 from sampled locations were significantly higher (P<0.05) than OSHA standard. While, that recorded for   RH, HCOH, TVOCs, PM₁₀ CO₂ & CO were significantly lower (P<0.05) than OSHA Standard.   Mean values recorded for all parameters were significantly different from the OSHA standard with exception of RH (F = 0.167, P>).

Table 3- Relationship between Air Quality and Workers Health Outcomes

^aDependent Variables: Air Quality

^bPredictors (Constant): Fatigue, Headaches, Eye irritation, Cattarh, Coughing

Findings: There is no relationship between perceived air quality and the overall health outcomes of the workers (F = 1.943, P>0.05). Since insignificant relationship was recorded between perceived air quality and workers health outcomes, it implies that the Null Hypothesis (H₀) will be accepted.