For example, have a look at the performance of different MERV rated filters, MERV 8 - 16 (hpac.com/industry-per...) For MERV 16, you can't say 1 micron particles will be trapped - they almost certainly will be, but not a definitive YES. 5/

Similarly, for MERV 13, particles between 0.3 and 1 microns, have about a 75% chance of getting trapped. Again, not a definitive NO or YES. More than an even chance, so not too shabby. 6/