well, if the condo is newly constructed, the building will be more airtight than something 10 or 15 years old and, of course, buildings built before that will not be too airtight at all.
there's also the issue of the materials used - most new construction has tyvek sheets added before siding is put on - keeps the building energy efficient also blocks most air circulation too.
your concerns are real. when a building doesn't breath, toxins (like those that plastics give off) stay inside and newer construction has more man-made components than older buildings (which are basically wood and brick/morter with no moisture barriers like the tyvek) so the air quality might not be so good.
spider
plants are one of those known to be a filter tho, so i'd say there is some other issue on top of the air quality.
do the
plants you are choosing have enough light for their requirements? what about water? do you use your tap water? if so, do you let it sit overnight so that the chlorine in it can dissapate?
there are also other things in the water that might cause a problem. for example, i've always had a fish tank. never had a problem with the water in nj; when i moved back to pa, something made me test the water. high levels of ammonia in it! good thing i tested before setting up the tank as i would have killed all the fish immediately! (there's a treatment that can be applied to remove the excess ammonia)
the spider
plant may have just reached the end of it's lifecycle. i'm not sure how long they usually live - 15 years sounds like a long time tho!
you can do tests for the air quality as well as what, exactly, is in your water. if you aren't getting sick, i wouldn't worry about it too much, tho. try choosing different
plants...things that are a better match to the conditions in your new home (sunlight levels as well as what direction your windows face).
