We need to cut down on the unpleasantness that our guest is bringing inside with him after going outside to smoke. Can anyone recommend a good air filter to help in this situation?
I already asked and a decontamination unit build in front of the door is not an option, neither is the guest staying elsewhere nor just not smoking. 
Thanks for any help.
Why is simply not smoking not an option?
If the guest is staying at your house, and your house is a non smoking environment, the guest should respect that rule, it’s not like going without their nicotine fix is going to kill them anyway…
Why don’t they use any of the available substitutes to get their fix, nicotine gum/patches/e-cigarette (note, do not use simultaneously )
If such a filter existed, I think it would sell better than I-phones ! Unfortunately, I don’t think such a “filter” exists.
The problem is that the smoke smell gets impregnated in clothes, hair, etc… So if allowing your guest to smoke (outside) is necessary, then the only real solutions that come to mind are:
As their host I would think you have some say in the rules:
Spray him with Febreeze every time he comes back in the house!
In my experience, people who reek of smoke reek because they re-wear their clothes or don’t wash their hair and and hands well. Or because they smoke in their closed car.
My vote is to tell your guest that your place is no-smoking, but you’re probably already nixed that option since you’re asking.
If it’s cold, have them hang their coat outside. Ask them to wash their hands when they return. Offer to throw their jeans in the laundry if you’re doing a load. Throw a ‘decorative’ blanket on the piece of living room furniture that they gravitate to.
And.
Febreeze.
You could try Genuine Filter Queen Vacuum Cleaner Cones and Charcoal Enviropure filters. They work great for dust and smoke.
They’re designed to work with Filter Queen vacuums and air cleaner/purifiers but you can build an adapter to use them with any vacuum. You’ll need a plastic or metal cone/funnel-shaped skeleton form to hold the filters and an adapter to match your vacuum. The filters would be placed on the intake side of your vacuum or vacuum hose. Bad air in - good air out (unless your vacuum output/exhaust already smells).
Or buy an old Filter Queen.
The problem with such a filter is that it doesn’t help until the air containing the smoke goes through it. That would take a complete exchange or 3 of all the air in your home. This could take hours.
A HEPA filtration system wouldn’t help by itself as the HEPA standard doesn’t cover smoke and odors. You’d need a charcoal filter for that. There are charcoal furnace filters available. Filtrete Pet Odor Reduction filter is one example.
Another option is to install a window fan in one room to exhaust the air outside and open windows to ventilate those rooms. Depending on where you live this time of year, your heater will be working overtime to keep up.
Still the best way to avoid the smell of cigarette smoke is to not allow it in the first place.
Buy him a long jacket and have him use it just for smoking outside and leave it outside before he comes in (a smoking jacket, as it were)- you can probably find one for cheap at a thrift store.
Have him wash him hands, neck, and face when he comes in from smoking. Have him Febreeze his hair.
Doing these things should cut down on the smell by at least 90%.
My partner has learned to stay outside after the smoke for as least as long as the time it took to smoke it. It has made a massive difference to what comes back in with her. Ask your guest to wander a bit after the cig. We have the same rule for the car, no butting out and getting straight in, too much gets into the car and I can’t ride in it (lest you think me a precious sort I have severe lung disease and smoke triggers very big badness, it is not just a yucky smell).
Perhaps this is why there’s none of your kind left. 
This. Even a light robe. If it has a hood, even better. Or have him wear a knit cap if there’s no hood to keep it out of his hair. Remove the items before coming back into the house. If there’s a mud room they can go for storage, somewhere removed from the other coats and stuff, you’ll want them there when not in use. And yes, going for a little walk around the yard or whatever for a few minutes after extinguishing will also help a lot.
An air filter in the house isn’t going to work when the smell is on a person. That’s like using an air filter to get rid of BO.
I agree that a smoking jacket is likely the most feasible solution. My suggestion is a cheap vinyl poncho – doesn’t absorb as much as a fabric would, can be stored in a grocery sack, and inexpensive to eventually replace.
Well, I am still around a little bit but I do accept responsibility for forgetting to have children so the line ends here, then they can make it official and call all the trackers down in Tassie dingbats.
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That’s not accurate. The only way for you to detect an oder, any oder, is for the scent molecules to enter your nose. In order to do that, the scent molecules must travel over the air currents, from the scent producer to your olfactory senses. In other words, the scent you detect is in the air.
I know of two ways to prevent your nose from detecting a scent that’s already present. Either mask the scent with another scent or remove the scent from the air by filtering it. Three if you wear nose plugs or a gas mask.
Place a frozen turkey on a table and you shouldn’t be able to smell it (assuming your freezer is clean and scent free). Leave it there for a week and the fowl will smell pretty foul. You’ll need to remove the offending bird AND filter the air for scent molecules AND clean every surface the fowl’s scent landed on to completely remove the oder.
Here’s an interesting, and sort of thread related, article concerning K9 scenting -
Information from: Bill Syrotuk - Scent and the Scenting Dog
http://policek9.com/html/scent.html
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Yes, an air filtration system needs to circulate air thru its filtering medium in order for it to work.
I suggested thursday next try Genuine Filter Queen Vacuum Cleaner Cones
and
Genuine Filter Queen Charcoal Enviropure filters. The Charcoal Enviropure filters do contain charcoal.
It’s not necessary to use a Filter Queen vacuum cleaner because it is the filters that do the filtering. It’s “easier” to use a Filter Queen vacuum but it’s far “cheaper” to build an adapter that uses the Genuine Filter Queen filters.
Any chance they would switch to a vapor/e-cigarette? I “smoke” mine (no nicotine) even in the car and it’s undetectable to anyone.
They could try the old stoner trick of just smoking right into the vacuum cleaner. I don’t think that trick ever actually fooled anyone, but if you had a vacuum with a hose and a decent air filter that might get the smell down to tolerable levels, combined with hand-washing.
It’s very accurate. It’s not a finite cloud of smoke, and once the cloud has been filtered, the scent is all gone. Just like with BO, the smoker is continuously releasing the molecules causing the odor. Those molecules will not go directly to the air filter. Enough will get to the OP’s nose for the OP to smell.
Thank you to everyone who took the time to respond to the thread! The suggestions are very helpful and are being looked into, especially the robe with a hood (or poncho) idea.
Guest does not smoke in the house. It is done outside, but when he waits one minute after smoking and then comes back inside it really doesn’t help. Most of the problem is that Guest just doesn’t care that it causes problems for anyone. Unfortunately he’s always been this way, so its not likely to change. Hopefully some of the suggestions here will help. 
My Sweetpea did end up getting a snazzy new air filter with a million different types of filtration including HEPA and charcoal. The charcoal makes me feel like a fish in a tank.
What kind did you get? My husband and I moved to a new place, and the downstairs neighbors smoke like chimneys. The smoke comes out from under their door (there’s an inch gap or so in places), and I’ve done my best to seal this place up, but occasionally we get a bit of a whiff of smoke, and would like to eliminate it.