Localized air pollution from open burning, waste disposal, and gas emissions remains difficult to monitor effectively, especially in inaccessible areas. Conventional air quality monitoring methods are often costly, stationary, and inadequate in coverage. We present AirborneSense, a novel unmanned aerial vehicle (UAV)-based monitoring system equipped with low-cost particulate matter (PM2.5) sensors, GPS, and environmental sensors (temperature, humidity, and barometric pressure), using the Global System for Mobile Communications (GSM) to transmit real-time data to the cloud. The HPMA1115 PM2.5 sensor was chosen for its high accuracy, R2 > 0.7, and a calibrated RMSE of 1.98, compliant with US EPA standards. Field tests were carried out at various altitudes and locations to evaluate system accuracy and adaptability. At higher altitudes, AirborneSense demonstrated its peak sensor performance with an R2 value of 0.78, maintaining consistency with reference analyzers (R2 = 0.73). The system effectively mapped pollution, revealing elevated PM concentrations in construction zones and significantly lower levels in rural areas. The findings underscore the potential of UAV-based systems to enhance spatial and temporal environmental assessments, providing a scalable, cost-effective tool for comprehensive pollution monitoring and management.