Spatial and Temporal Factors of Air Quality in Surabaya City: An Analysis based on a Multilevel Model

Transport sector has been one of the major sectors to worsen the air pollution in Surabaya City. Air pollution concentration vary across location and time, however it hasn’t been clarified yet. To fill in this gap, this study examines spatial and temporal variations of air quality based on a multilevel model. We use six air quality data NO, NO2, SO2, O3, CO and PM10, from February 2001 to September 2002, measured with interval 30-mins at five monitoring stations which represents land use characteristics at different locations. Therefore it is hypothesized that high variance of air quality should be observed among stations. To obtain how land use affects the concentration, we use monthly data. A multilevel model was estimated by including a group-level predictor (here, refers to stations) and individual (refers to measurement at the same location). Temporal variations were analyzed by introducing seasonal, day-to-day, and peak concentration time variations. We note that the shares of locations are small, indicating that the concentrations do not depend on locations. Also, the model result shows that the air quality related to traffic volume (NO2) are generally lower in suburban area (Sukomanunggal). Moreover, the quality of SO2 and CO is lower in suburban indicating low industrial activities. We also notice an upward trend of air pollution, indicating the growth of Surabaya's vehicle volumes. Significance interaction between NO, NO2, and O3 was confirmed. The most obvious meteorology impact on all air pollutants are coming from all factors. There is the necessity to urban planning management to add green spaces as part of efforts to reduce ambient concentrations.