Adding a spice kitchen may help. For an additional info please read the following discussions at https://www.houzz.com/discussions/just-curiouswhat-is-a-spice-kitchen-dsvw-vd~700191

Maybe mom's kitchen needs a heavy duty exhaust fan - vented to the outside?

@tiamay: When we renovated the basement apartment, it was determined there was no way short of changing the kitchen footprint (cost-prohibitive) of adding an outside-vented range hood. What she wanted (and what we installed) was an above-the stove microwave with exhaust fan. The attached photo shows the kitchen prior to their move. (we hadn't yet changed the pendant light fixture, though!)

@Curt D'Onofrio: thank you for referring me to such an interesting article! If ever we move or need to renovate, that is definitely something to consider. However, at this point we are out of renovation money, as we renovated the upper level for ourselves while living in the basement prior to doing the downstairs renovations. And my parents are quite happy with their new home, so it's really only me who has a problem: my overly sensitive sense of smell, lol.

Could you ask your mom to open the kitchen window a tad and close the kitchen door while cooking? Living in NC it cannot be a heat related problem, I would think.
Good luck with the rest of the renovation!

@w110129: Yes, the window is now open a bit during cooking times, but the stairwell is in such close proximity to the range (closer than the window) that it acts as a chimney to draw the odors up. And I can't ask her to not fry onions, etc., because she's been cooking like that since she learned to cook, lol. Here's a picture of the stairwell I refer to (the range is just around the left hand-side corner of that blue wall:

It sounds like you have run out of ( inexpensive) solutions to your dilemma. I hope other nice things will make up for it. Courage and keep smiling ;-)

Why fight it? Just eat with her, then you won't have to cook!

@charleee: Well, we do eat with them occasionally. The problem is odors are my Achilles' heel, as in I get physically ill from some of them. And having my house smell of something I'm not cooking isn't good. I'm trying to reduce her cooking time by asking them to eat with us as much as possible, but by the same token I don't want to take away something she still loves to do. It's a quandary, and one I'm hoping to alleviate by keeping the smells contained. I'm to the point of asking our electrician to install a bathroom exhaust fan just outside the staircase, where it would be easy to vent to the outside, but I don't know how much that will cost yet. That's why I posted here: for ideas on how to help with the smells.

My first question was going to be, "Do you have carpets?" The runner on the stairs has answered that question (at least for the stairs). The dilemna is one of air movement, venting, "heat rises", etc.

Without adding MORE barriers (like "outside" doors, etc) there are going to be very few options. You may have to look for an air purifying system (the type used by asthmatics). These can be retrofit to air conditioning units OR the cheaper ones will be free standing at the top of the stairs. A "good one" should be a few thousand dollars - and you should be able to take home a floor model before purchasing.

You may want to find out what people with Multiple Chemical Sensitivity Syndrome (yes it exists) do when faced with concerns such as yours. The fixes are often the same - odours come from chemicals and chemicals produce odours. Eliminate one and you have fixed the other.

No, no carpets. What you see on the stairs is the stair-lift for my parents. And thank you for your ideas - I'm going to check into the Multiple Chemical Sensitivity Syndrome, as well as the air purifying units.

Getting rid of aromas in air is a challenging question. Love a challenge. I didn't even think of a air purifier. See ? That's why i love this site. Nancy, If you do go that route, please update to let us know how it worked out. Thanks

I think the air purifier can make a big difference (get 2, one for her space and one for yours). Another idea would be to get a free standing floor fan to run, aimed at the open window, when she cooks. I have a hepa filter attached to my central a/c, and when we run it, the air smells so good, fresh and clean. I am sensitive to smells as well, but we got the hepa filter because we have pets, allergies, and mild asthma, not for alleviating odors.

good advice, thank you! :)