We need some expert help here to debug a problem that we are having in the basement.

Our house has a daylight basement that's finished with Brazillian cherry. For the last 9 months, we have been battling with a very strong smell in the basement. We did re-sand and stain the floor back in November 2010. We use Bona traffic water based stain. After the work, there is always some lingering smell. For the first few months of this year, we thought the smell is probably coming from the crawl space behind the basement. But after spending $$$$ to improve the crawlspace, we still have this strong odor in the basement. Even though we also have odor in the crawl space, that smell does not cause headache at all. Just simply unpleasant. However, the odor in the basement is kind of sour, or acidic that causes my throat to ache. That's when we start suspecting that there might a problem with the floor.

When we refinished the Brazillian cherry floor, we did the for both basement and main living level. The main living space does not have this smell at all. The basement floor is built on the plywood which in sitting on the slab. Is it normal for cherry floor ( about 6 years old) to emit smell after being finished 9 months with water based Bona traffic? The smell gets worse when it is humit outside or it's cold at night.

I read some of the floor finishing products may have fomaldyhyde. Is this a case for Bona traffic? I also want to add that a few weeks after we finish the floor, we did use an anti-microbia product called Terminator to wipe the floor. Don't know if that chemical may interacts weird with the floor finish. But the floor itself looks fine. When we put our nose next the floor, it's hard to tell whether it has stronger oder than the ambient environment in the room or not. But the room definitely has a very strong odor.

Anyway, we haven't ruled out other root causes yet for this smell. Just want to check in and see if anyone has similar experience.

Thanks