Quite a few studies have been done with personal air purifiers and whole house air filter systems. The bottom line is that the personal systems are great for if you travel and such but for long term use, they don’t match up to the whole house air filter.
With the individual units, depending on the brand, air may or may not actually be moved through the unit to remove the particles. Some do, but some don’t.
With the whole house filters, the air moves as it should along with the heating and air conditioning units. When it does, the framework and the duct work trap the contaminants thus creating a nearly pollution free environment.
Studies do favor the home air filter systems but do not totally discount the individual units. Since the filters do get dirty on the individual units, it is obvious they are trapping at least some of the contaminants.
What About Older Houses?
Believe it or not there are still many, many houses which do not have heating and air conditioning duct work. There are still broilers and window air conditioners throughout the country.
Obviously, with no duct work, the individual units would certainly be better than having nothing to clean the air. They are going to trap at least part of the unwanted particles which keeps them out of the lungs of the residents. While home air filters may be the best, it is just not always practical.
New Houses and Air Filters
There are some, but certainly not all contractors and home builders that think to include a whole house air filter when designing and building the house. While that is true in some cases, there are just as many that have the regular filters and the open duct work (which will one day have to be cleaned).
If it is your house, insist on a home air filter system so you can have a contaminant free home from day one. Your house will stay cleaner, your family will be healthier and everyone will notice the fresh, clean air in your home.