EMISSIONS OF NITROGEN OXIDE FROM CARS, TRUCKS AND BUSES

During a long time regulated as well as unregulated automobile exhaust emissions have been measured at the automobile exhaust emissions laboratory. Among the unregulated, nitrogen dioxide has been measured in passenger cars as well as heavy trucks and buses with diesel engines. Some literature background is also included. The results show that nitrogen dioxide is 5-10 percent of the nitrogen oxide emission, but, at low load, at high excess air, with certain filters/catalysts and from a diesel passenger car, the percentage of nitrogen dioxide can range from 25 to almost 100. For gasoline fuelled passenger cars conforming to Swedish a10-regulations a strong negative correlation can be seen between fuel consumption per time unit and the percentage of nitrogen oxides being nitrogen dioxide. This means that high loads are associated with low nitrogen dioxide percentages and idle, light cruising and decellerations give low percentages of nitrogen dioxide. For other cars and parameters correlations are low or not existing.