If a person walks indoors after smoking, they carry dust with them. But what about the gases from the smoke? Do those stick to the person or persist in the area and continue to pose a threat?
The answer to your question is thirdhand smoking (THS):
From the American Nonsmoker's Right Foundation (ANRF), "Thirdhand smoke consists of the tobacco residue from cigarettes, cigars, and other tobacco products that is left behind after smoking and builds up on surfaces and furnishings."
So the chemicals from smoking do stick to a person and persist in the area. In regards to whether they pose a threat, research is still continually being done to assess the harm/adverse effects on health. So far, researchers have found that the leftover nicotine from smoking can react with nitrous acid (in indoor air) to form carcinogenic compounds. A different paper reported the reduction in body mass when mice were exposed to THS, explaining the potential for harm in humans.
From what I've read, there hasn't been any strong claims on the threat as seen in secondhand smoke. But it might be wise to consider "There is no safe level of exposure to tobacco smoke.", a view that is supported in the final two papers of my references.