Researchers studied how different combinations of chemicals in the air can create particles that affect air quality. They looked at mixtures of o-cresol and α-pinene, which are found in both human-made and natural sources. By using special instruments, they found that the particles from these mixtures have different levels of volatility, or how easily they evaporate. Some new chemicals formed in the mixtures made the particles less volatile, while others made them more volatile. This means that the particles from mixtures have a volatility level in between those from individual sources. This study gives us new insights into how different chemicals interact in the air and affect the formation of particles that can impact our environment.