A newly recognized pollutant is widely present in the atmosphere A new study shows that a specific type of silicone, the so-called methylsiloxanes, is widely present in the atmosphere across diverse environments. Also, concentrations appear to be much higher than expected. According to the researchers, this raises concerns about their potential—yet poorly understood—effects on human health and the climate. Methylsiloxanes are commonly used in industry, transportation, cosmetics, and household products. The study was supervised by Utrecht University and the University of Groningen, and the results are published in Atmospheric Chemistry and Physics.