The article says:
“The results are strengthened by the authors controlling for levels of traffic pollution, which was recently shown to be associated with dementia as well as other diseases.”
“The results are strengthened by the authors controlling for levels of traffic pollution, which was recently shown to be associated with dementia as well as other diseases.”
I think the idea is that people living in the same building should all have roughly the same particulate and pollution exposure, but people living on a road-facing side of the building will have more exposure to road noise. It's an extremely clever study design.