Is there really third hand smoke?

Yes, thirdhand smoke (THS) is real. It's the residual nicotine and other chemicals left on surfaces and in dust after someone has smoked, even if it was hours or days ago. This residue can react with chemicals in the air, creating new, more toxic compounds. THS can be breathed in or ingested, and has been linked to several health risks, including lung cancer, heart disease, and asthma, especially in children.