Local Traffic: a Source of Emissions
Air pollutants found within the vale are generally associated with vehicle emissions. A summary of the main pollutants, including and their sources, can be found below.
The main source of Nitrogen Dioxide in the Vale is road traffic emissions. This pollutant is therefore monitored at a number of road-side sites by passive diffusion tube and at one background site by a real time monitor. Levels are generally low and below the national air quality standards, although a small number of traffic hot-spots, where concentrations are higher than normal, have been identified in Aylesbury Town.
The principal source of airborne particulate matter is road traffic emissions, particularly from diesel vehicles. In our District historical monitoring and the air quality review and assessment program has shown that levels are below the national air quality standards.
Ozone arises from chemical reactions, driven by sunlight, between oxides of nitrogen and hydrocarbons derived mainly from vehicle exhausts. These reactions may take place over long periods and thus, ozone produced at one site may be carried for considerable distances. Most of the ozone reaching this country actually originates in Europe. Because of its trans-boundary nature ozone is very difficult to control and it is, therefore, not included in the national air quality Review and Assessment program. Despite this, ozone can be a problem particularly in the hot, sunny months of the summer and when the winds originate from the continent. During these conditions, so-called ozone episodes may occur anywhere in the UK.
Benzene is a hydrocarbon resulting mainly from the use of petrol and oil. Monitoring of roadside concentrations by diffusion tube was undertaken at four sites in the District between 1996 and 2000. All results were consistent with the national, downward, trend and no problems were found.
Date Updated: 09/08/10