Compared to other types of air purifiers with washable pre-filters and/or filters that need to be vacuumed every few weeks, this is a much more hygienic and convenient process
The none-too-subtle message was that if the doctor, with all of his expertise, chose to smoke a particular brand, then it must be safe
[6] Mishra A, Chaturvedi P, Datta S, Sinukumar S, Joshi P, Garg A
The same is true of the Coway Airmega 400S, a smart version of the 400
While I suggest in a comment at the PLoS ONE study site that we are seeing category crossover due to the studys dependency destroying definition of cold turkey ("gave up cigarettes all at once" instead of the actual definition, "abrupt complete cessation of the use of an addictive drug"), Table 7 footnotes indicate that there was also "missing data." Regardless, cold turkey crushed the competition