Try it if: You want to minimize allergens preventively.
How it works: Installing a particle-catching furnace filter from 3M Filtrete in homes with forced-air systems reduces exposure to a range of triggers, including dust, pollen, and mold. (Filters cost less than $20 at furnacefilterwarehouse.com.) James Sublett, an allergist in Louisville, Kentucky, suggests getting one with a residential MERV rating of 12. (MERV ratings indicate how effective a filter is at catching allergens; 12 is the highest rating.)
Good to know: Change it every three months. Leave the system’s fan on to keep clean air circulating.