Out of curiosity, a quick pubmed (the 'search engine' of scientific publications) brings up this Norwegian study
https://www.ncbi.nlm.nih.gov/pubmed/29360764
"We have not found updated peer reviewed evidence that carpeted floor is unproblematic for the indoor environment. On the contrary, also more recent data support that carpets may act as a repository for pollutants which may become resuspended upon activity in the carpeted area. [...]
I also note that a conference paper was presented a few years ago, which concluded that
" Intensive carpet cleaning can be highly effective in reducing both surface allergen and airborne particle counts"
https://www.researchgate.net/publicatio ... th_Carpets
The operative word being
intensive - if you read the abstract it talks about hot water extraction, which requires bulky, expensive professional machines. We have it done about twice a year but I don't know anyone who owns one of these machines.
As for the Swedish study, is that the one which simply compared the occurrences of allergies in the '70s vs the '90s, and noted that in the 90s there were fewer carpets but more allergy sufferers? That is not exactly a like-for-like comparison! All kinds of allergies have increased over the last decades, and no one really knows why, it could be any combination of environmental factors, different lifestyles, different reporting (maybe these things were underreported in the past).
To make a comparison, you can't just say: we eat more avocados now than our parents did 20 years ago, we suffer more from X, so avocados contribute to X!!!