Common silicones from engine oil and cosmetics are far more prevalent in the atmosphere than expected, making up to 4.3% of organic aerosol mass. This stable pollutant is now omnipresent in urban and rural air, potentially impacting both human health and cloud formation.

Abstract. Synthetic pollutants have emerged as a widespread environmental concern. Recently, large molecular methylsiloxanes were identified in traffic emissions. Here, we show that large molecular methylsiloxanes are widely present in atmospheric particulate matter across diverse environments, including urban, coastal, rural, and forest sites in the Netherlands, Lithuania, and Brazil. Overall, methylsiloxanes of varying molecular sizes account for approximately 2.0 %–4.3 % of the non-ref…