The utility model discloses a special fresh air unit between public health, including the new trend filter, the new trend filter is connected with the heat exchanger, and the heat exchanger is connected with the forced draught blower, and new trend filter, heat exchanger and forced draught blower constitute air supply passage in proper order, the heat exchanger still is connected with the air exhausting filter, and the heat exchanger still is connected with the exhaust fan, and air exhausting filter, heat exchanger and exhaust fan constitute the passageway of airing exhaust in proper order. Through retrieving indoor cold volume (or heat) of airing exhaust, the sensible heat exchanging of existing conventional fresh air ventilator group reduce the air conditioner load demand in room, but the indoor proportion of airing exhaust of sending of further still automatic adjustment makes indoor certain negative pressure that keeps, avoids other building region of cross contamination. When if the conflagration takes place, it is bigger at the cigarette mist concentration of air exit, can early discovery fire dangerous case, if when detecting cigarette mist concentration above the setting value, both can report to the police, can give relevant managers with message routing through the GSM module again, strengthened the security performance, in time discover the conflagration.