Thompson Tips for Conquering Allergies: "Build it tight, ventilate right!"
Housekeeping - before you spend any money, start with elbow grease. It isnt' sexy, but it's really effective. Vacuum religiously, dust, dust, dust, use mats at doors, don't keep towels longer than a few years.
Pleated furnace filter - These remove much smaller particulates out of the air (MERV), must change them as recommended, thicker filters last longer. Bath & Kitchen fans also remove concentrations of pollutants.
HEPA Filtration - Units are pretty good. Whole house is better (but considerably more expensive).
HEPA on an Air to Air Exchanger (ERV) - this is hospital quality, fresh & filtered air, right in your home.
Fresh, clean air is something you may not notice at first but once you experience it, you'll love it!
The acronym HEPA stands for "High Efficiency Particulate Air" or "High Efficiency Particulate Absorbing" Technically speaking, the US Centers for Disease Control defines a HEPA filter as an air filter that removes more than 99.97% of particles 0.3 microns or larger at a specified flow rate of air.
The acronym MERV stands for "Minimum Efficiency Reporting Value"