Prepare for spring allergy season and receive a free filter (a $147.00 value) when you purchase a new Blueair Air Purifier this month. Buy a new Blueair model 201, 402, 501, or 601 with Particle Filter or Deluxe with SmokeStop filter and receive a free filter when you mail in a coupon with the UPC code. Offer ends April 30, 2006. Browse the selection of Blueair Air Purifiers at achoo! ALLERGY.