Furthermore, NOx has NO2 in significant quantity ; produced under high temperature from the reaction of nitrogen (N2) and oxygen (O2) during kiln firing (Michael 1995). It is reported to produce acid streams and oxygen depletion in water bodies, and upsets the existing chemical balance to aquatic wildlife (U. S. EPA 1999a). In humans, it causes bronchitis and emphysema, reported by Clean Air (2007). A benchmark emission of NO2 in the range of 200 mg/m3 to 400 mg/m3 for a typical cement industry is recommended by World Bank group (1998) and VDZ (2002); also, and eight-hourly average NOx limit of 22.8 ug/m3 are recommended by FEPA (1991).