This study clearly demonstrates that urban commuters, especially two-wheeler users, are exposed to extremely high concentrations of particulate matter (PM2.5 and PM10) during peak traffic hours. The recorded exposure levels exceed the WHO air quality guidelines by a wide margin, reflecting the severe air quality challenges in densely populated urban areas. Two-wheeler users, who are often exposed to exhaust emissions from nearby vehicles without any physical protection, face the greatest health risks. With exposure levels reaching 6.33 times the WHO limit for PM2.5 and 3.50 times for PM10, these commuters are particularly vulnerable to respiratory and cardiovascular health problems. Numerous studies, such as those by [24–26], have found similar trends, where the proximity of two-wheeler users to vehicle emissions makes them disproportionately susceptible to harmful pollutants. The high levels of particulate matter encountered by this group can lead to long-term health consequences, including chronic respiratory conditions and increased mortality risks.
Pedestrians are also not immune to these risks. The findings show that their exposure levels to PM2.5 and PM10 are 4.67 and 2.27 times higher than the WHO guidelines, respectively. This suggests that even individuals walking along city streets are subjected to elevated levels of pollution, often due to their proximity to high-traffic areas. Pedestrians, especially those who regularly walk during peak traffic hours, face long-term health hazards, with studies like those by [27–29] indicating that such chronic exposure can lead to an increased risk of cardiovascular diseases, lung cancer, and asthma. Despite having less exposure than two-wheeler users, the health risks for pedestrians remain considerable, particularly when walking near roads with heavy traffic.
The fixed-site monitoring station, while intended as a reference, also recorded pollution levels significantly higher than the WHO guidelines. This indicates the widespread nature of poor air quality in urban settings. Although fixed sites provide useful background data, they tend to underestimate the real-time exposure commuters face, as seen in the mobile measurements taken for this study. The consistently elevated levels across the modes of transport show that pollution is not confined to certain hotspots but is rather a pervasive issue across urban environments. This aligns with findings from [30–32 ] which showed that fixed monitoring stations often fail to capture the full extent of mobile exposure to pollution, particularly in areas with high traffic density.
These results highlight the urgent need for comprehensive mitigation strategies to tackle the high levels of particulate matter in cities, particularly for vulnerable groups such as two-wheeler users and pedestrians. One key solution is to reduce traffic emissions, as vehicles are the primary source of urban air pollution. Policies that promote cleaner, more efficient engines, electrification of transport, and stricter emission standards could drastically reduce the concentration of pollutants. Additionally, improving vehicle design, particularly for two-wheelers, to include protective features against inhaling polluted air, may offer some degree of protection. For pedestrians, creating dedicated walking lanes farther from traffic or promoting green buffers along walkways could help reduce their exposure to harmful pollutants.
Promoting the use of public transport can also be a powerful tool in reducing traffic emissions, as fewer vehicles on the road lead to lower overall pollution. Encouraging citizens to use public transportation or alternative forms of commuting like cycling can reduce the number of individual vehicles on the road, thereby lowering emissions. However, these strategies alone may not be sufficient. Fixed-site monitoring, while useful, should be supplemented with mobile exposure assessments to better understand the real-time exposure that commuters face while in transit. Mobile measurements provide a more accurate representation of the fluctuations in pollutant concentrations during specific times, such as peak traffic hours, and can guide targeted interventions more effectively.
In conclusion, long-term exposure to elevated levels of PM2.5 and PM10 poses significant public health risks, particularly in urban environments where traffic emissions dominate. These risks necessitate immediate action, both in terms of policy and urban planning, to protect vulnerable populations from the harmful effects of air pollution. Reducing overall exposure through emission control measures, infrastructure improvements, and enhanced monitoring systems should be prioritized to ensure better air quality and healthier urban populations.