Spatio-temporal variability of ambient air quality under the influence of private vehicle-dominated traffic activity in Yogyakarta Urban Area (Indonesia)

Air quality is one of the environmental issues that has become a global concern and a priority in the Sustainable Development Goals. This study aims to evaluate the ambient air quality on secondary roads in the urban area of Yogyakarta under the influence of traffic levels. The air quality variables in this study include PM2.5, PM10, CO2, HCHO, and TVOC. Data collection was conducted through observation and literature study. A total of 134 data points were collected from 37 measurement locations in this study. The data were analyzed using matching, geographic information systems (GIS), statistical methods, and descriptive approaches. The results indicate that CO2 is the only parameter significantly correlated with traffic activity. More specifically, CO2 is significantly related to motorcycles, where an increase in the number of motorcycles corresponds to a rise in CO2 levels. Spatially, there is a difference in average CO2 levels between urban and suburban areas. CO2 levels are higher in suburban areas than in the city center due to commuter traffic from surrounding areas. HCHO and TVOC do not show a significant correlation with traffic levels. Meanwhile, the number and intensity of cars on the road, although not as numerous as motorcycles, contribute to increased levels of PM2.5 and PM10. This study provides new insights into the relationship between private vehicle activity and air quality in non-industrial cities, contributing to the development of regional theories in Southeast Asia on the environmental impact of transportation activity on secondary roads. Additionally, the findings of this study imply the need for spatiotemporal traffic management, not only to prevent traffic congestion but also to control pollution levels.