Vegetationens inverkan på luftmiljön


Vegetation impacts the local air quality both positively and negatively. The positive effect is that air pollution concentration can be reduced by deposition on the vegetation surface and the air filtered. The total amount of air pollution is thus reduced. The negative effect is the ability of vegetation to act as windbreaks reducing the wind speed, which reduces the dilution of local emissions and can increase the levels in the surrounding area. In dense urban environments where dilution already without vegetation may be limited, such as in narrow street canyon with traffic emissions, this is a big risk. Vegetation can also be placed as a barrier between the emission sources (often major traffic routes) and the population, so that the transport of pollution from the source to the population may be limited, and the air is filtered on its way. This report describes the research in the area at present, and is mainly based on the scientific literature. It is at present difficult to describe vegetation in a way that simply relates to its effect on air quality. An example is the vegetation density can be measured in several ways, and best describes the effect either on wind movement or on deposit. The particle size of the pollution is of major importance to the processes, while chemical effects have been omitted in the description. Vegetation-curtains and different types of street canyon are studied with references to all the studies that is reported. The recommendations, explained in detail in the report, are: • place the vegetation near the source of air pollution, where the concentrations are high, increasing the ability to filter out pollution or redirect the polluted air, • ensure that the vegetation does not reduce the dilution of pollutants, for example avoiding close planting of dense trees in narrow and busy street canyons, where pollution is not easily diluted, • use vegetation barriers between transport and population, to introduce a deposit surface and control of the air movements, but preferably low hedges if dilution is limited at the site, • wall and roof vegetation in dense urban environments increases the deposition surface and has a limited restriction of ventilation compared to free-standing vegetation, • plan the vegetation from the start in view of all the effects of vegetation that can occur in a complex urban environment, and level different environmental effects against each other.The result has also been published scientifically in Janhäll (2015) “Review on urban vegetation and particle air pollution – deposition and dispersion” in the journal Atmospheric environment, 105, 130–137.



Cost Benefit Analysis (CBA) workshop in Stockholm

An open seminar and workshop in Stockholm will be held on 25-26 April 2018. The workshop deals with the use of CBA as a basis for decision-making in the public sector. The workshop is organized by, among others, Professor Jan-Eric Nilsson, VTI.



Modal shift for an environmental lift?

Investigations in Sweden and other countries suggest a shift of goods transport from road to rail and waterborne transport to reach environmental and climate objectives. VTI is leading a new project to investigate how the modal shift can contribute and what...


Automation and digitalisation are making rail competitive

Road transport is developing rapidly and its productivity has increased sharply. Rail transport, however, has not developed at the same rate. Automation and digitalisation are essential if rail freight in Europe is to survive.


New research is creating a driverless logistics chain

The research project Born to Drive has come up with a system that allows new cars to move, without a driver, from the production line out to the parking area prior to being transported elsewhere. The vision is to automate the entire logistics chain from...


VTI testing automation in EU project

VTI is leading a series of tests in a major EU project on automated driving. The first driving tests were carried out n a test track in Slovenia in December. The project will focus in part on acceptance among different groups in society, in part on...


Freight transportation on road and rail analysed

Freight transport accounts for a large proportion of the emissions, noise and congestion produced by road traffic. Transporting freight in larger but fewer lorries could reduce the problem. At the same time it might entail freight being diverted from more...


Millions for research into maritime transport and the environment

Maritime transport is a major source of emissions of harmful air pollutants and carbon dioxide. In a new project, a research team from the Swedish National Road and Transport Research Institute (VTI) and the University of Gothenburg has received SEK 6.4...