This study explores the relationship between air quality and tree quantity before, during, and after the Metro Manila smog event on September 22, 2023. The Kriging method was used to interpolate PM10 AQI readings across the study area. Tree count was obtained through volunteered geographic information and verified through the DeepForest tree crown detection model. Geographically weighted regression results indicate that higher tree quantities correlate with improved air quality for monitoring stations in the north and selected stations in the center of the study area located near residential areas, rivers and green open spaces. However, the positive effect of tree quantity on air quality was not evident for monitoring stations located in the west where the congested former capital near the bay is located, and in monitoring stations near industrial, business and commercial areas.