The existence of CO in a vehicle park indicates that other dangerous fumes (e.g. benzene) will also be present. As a result of this, the German authorities have lowered the limits for CO in car parking services from 100 ppm to fifty-60 ppm, according to the federal state in dilemma. https://basementventilation79011.life3dblog.com/35240660/not-known-details-about-basement-ventilation