This page shares publicly available air purifier performance test data from independent government-sponsored bodies. The equipment concerned was bought on the marketplace and air purifier manufacturers played no part in the testing or the reporting of the results. See links at the bottom of this page for the sources of the data.
The tests are:
1) A test of the performance of store-bought air purifiers carried out by the Shanghai Consumer Council early in 2013.
2) A test of air purifiers carried out by Consumer Reports of the USA in 2009.