The 503 Blueair is a very solid machine. Made in Sweden the 501 is one of our most popular room purifiers for asthma sufferers. We find this unit an excellent alternative under $550 dollars tag. When we test the 3 we found it very quiet at lower speed and comfortable as well at the highest setting. With more than 5 lbs of activated carbon this particle and gas filter configuration is very effective against odors, light chemical control and light smoking. This unit comes with 4 speed settings and offers and features a replacement filters indicator.I t is manufactured by a serious company that offers one of the longest limited warranties in the industry. If you are an asthmatic and have enough space the 503 is the unit for you
The 503 is very efficient and really gets the job done. Four fan speeds give you full control. Good for rooms up to 580 square feet at 6 air exchange per hour. It has a 5 years limited warranty.
The filters replacement procedure is not so smooth and for cleaning the fan it gets a little bit complicated. There is a cage built around the fan assembly, so you can't clean the fan unless you take the cage apart. The replaceable Hepa type air filters are costly, and should be changed every six months.