AbstrakUdara merupakan komponen vital bagi kehidupan, namun peningkatan jumlah kendaraan, pembangunan kawasan, dan pertumbuhan penduduk perkotaan menurunkan kualitas udara ambien. Penelitian ini bertujuan mengevaluasi kualitas udara ambien di tepi jalan serta memprediksi penyebaran polutan CO dan PM₁₀ di Kecamatan Cimahi Selatan menggunakan model CALINE 4. Metode penelitian meliputi pemantauan kualitas udara, survei kinerja lalu lintas, dan pemodelan dispersi polutan berdasarkan data meteorologi, volume kendaraan, dan faktor emisi. Hasil penelitian menunjukkan konsentrasi tertinggi SO₂ 40,36 µg/Nm³ atau 26,9%, CO 6.675 µg/Nm³ atau 66,8%, NO₂ 22,33 µg/Nm³ atau 11,2%, PM₁₀ 68,20 µg/Nm³ atau 90,9%, dan PM₂.₅ 32,20 µg/Nm³ atau 58,5%, seluruhnya masih memenuhi PP No. 22 Tahun 2021. Kinerja lalu lintas berada pada LOS C, dan prediksi dispersi menunjukkan konsentrasi tertinggi pada area downwind searah angin dominan. Pengendalian emisi dan sosialisasi masyarakat disarankan. Kata kunci: CALINE 4, kualitas udara ambien, pemodelan dispersi, polutan CO, PM₁₀ AbstractAir is a vital component for life; however, the increasing number of vehicles, urban development, and population growth in urban areas have contributed to the degradation of ambient air quality. This study aims to evaluate roadside ambient air quality and predict the dispersion of CO and PM₁₀ pollutants in Cimahi Selatan District using the CALINE-4 model. The research methods include air quality monitoring, traffic performance surveys, and pollutant dispersion modeling based on meteorological data, vehicle volume, and emission factors. The results show that the highest concentrations were SO₂ at 40.36 µg/Nm³ (26.9%), CO at 6,675 µg/Nm³ (66.8%), NO₂ at 22.33 µg/Nm³ (11.2%), PM₁₀ at 68.20 µg/Nm³ (90.9%), and PM₂.₅ at 32.20 µg/Nm³ (58.5%), all of which remain within the limits of Government Regulation No. 22 of 2021. Traffic performance was categorized as LOS C, and dispersion predictions indicate the highest concentrations occur in downwind areas aligned with the prevailing wind direction. Emission control measures and public awareness campaigns are recommended. Keywords: CALINE 4, dispersion modeling, roadside ambient air quality, CO pollutant, PM₁₀