Ammonia Emissions from Vehicles and the Effects on Ambient Air Concentrations.

Air concentrations of gaseous ammonia (NH3) have been measured in the vicinity of roads in Bavaria and Austria. The measurements have been performed using passive samplers and a continuously working denuder system. Based upon the comparison between different urban locations in Munich and Salzburg a relationship between the mean NH3 concentrations and the traffic density could be found. An analysis of hourly measured ammonia data from an important junction in Munich reveals similarities with the daily variations of other gases emitted by vehicles. The mean concentrations measured near traffic crossroads and an highway were comparable to those observed in the vicinity of numerous agricultural sources. The WHO guideline, 8 mug/m(3) as an annual average for the protection of vegetation, was exceeded at the urban station with the heaviest traffic