In this study, we explored how tiny particles in the air, known as aerosols, have changed over time in two mountainous areas in Austria and Switzerland from 2007 to 2023. By using special instruments that measure sunlight, we tracked these changes and found that the amount of aerosols has been decreasing in both locations. This is important because aerosols can affect both our health and the climate. This work is crucial for understanding air quality trends in mountain environments.