Nitrogen Oxides (NOx)
Data on pollutant emission inventories and air quality index reported for the ZMCM can be found in local authority information web page:
Historical data of pollution at five specific parts of the city are available for ozone, carbon monoxide, sulphur dioxide, nitrogen dioxide and inhalated particles (PM10), pollution standard indexes (IMECA, Indice Metropolitano de Calidad del Aire), and lead concentration. 1996 data of polluted days above local standards.
NOx and HC are precursors of photochemical smog. In the formation process, part of NOx is divided to produce an atom of oxygen which reacts to form ozone (O3) at ground level. The oxides of nitrogen are mainly formed in combustion chambers (such as car engines) when the nitrogen in air is heated above 2500oF. To reduce NOx emissions, burning temperature has to be reduced; burning time shortened, or air concentration decreased. Specific effects of this pollutant on human health have also been detected.