Some of my family members suffer from asthma and allery to dustmites
and the few changes that seem to have helped are:

-- Using a bagless vacuum cleaner ( I have a Dyson ) ..never loses
suction power. They are better than ones with bags any day, since the
bags do clog no matter what kind they are after using just a couple of
times which affects suction power.
-- Reducing carpeted area in the home ( said to be the most effective
since its the breeding ground for dustmites ) by opting for
hard/resilent floors rather than wall to wall carpeting in as many
rooms as possible.If floor tiles are not the ideal choice ( they are
hard, noisy and cold under the feet)there are other options such as
flotex ( very good for children's rooms since its smooth like resilent
floors, noiseless and warm like carpet), linoleum or parquet/laminate
floors etc . I do not prefer vinyl floors as they offgas and affect
air quality within the home.
-- Not allowing pets in carpeted areas
-- Keeping kitchen grease free and clean to keep roaches away.

We've never tried boric acid so I cant say anything about that.