The influence of microplastics on atmospheric processes, notably their potential influence on ice nucleation in clouds, remains a subject of uncertainty. Our results demonstrate that certain microplastic samples, specifically PP-needles c , PP-fibers b , and PET-fibers b heterogeneously nucleate ice in the immersion freezing mode at temperatures between -15 and -25°C and have 𝑛 𝑠 (𝑇)-values similar to fungal spores and volcanic ash. The ability of microplastics to freeze at these relatively warm temperatures suggests they can be removed from the atmosphere by ice nucleation followed by precipitation, which may modify their long-range transport to faraway regions and their distributions throughout the atmosphere. Our results are consistent with field measurements by Kozjek et al. who observed fibrous microplastics inside hailstones. Exposure to O3 and UVC+O3 led to a reduction in nucleation temperature for two (PP-needles c and PP-fibers b ) out of the three ice-active microplastics.