Abstract: An apparatus to purify fresh air contains at least three types of filters such as high efficient particle filter 5, chemical filter 6 and two stage electrostatic filters 2. The filters are secured to fresh air unit 1 that is secured to the wall 4 or window 11 of the building. Particularly, the present invention contains low noise fan 7 to reduce noises entering from outside. The particle filters and chemical filters are either in rolled form or in plate form with protrusions to have effective filtration. More particularly, the present invention relates to an apparatus for purifying freshly supplied air from outdoor environment and recirculates the indoor air by using new type easily installable and serviceable, filters that are environmentally friendly biodegradable filters.