Helsinki considers restrictions on car traffic because of increased air pollutants

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Air quality assessments conducted by the Helsinki Metropolitan Area Council (YTV) last year indicated that concentrations of nitrogen dioxide originating from traffic along Mannerheimintie and Hämeentie exceeded the limits set by the European Union.
      The concentrations of nitrogen dioxide exceeded the annual limit in the Helsinki metropolitan area for the first time last year. Even particle concentrations exceeded the limit, but this happened already in 2003, according to the mobile monitoring station in Runeberginkatu.
     
The city is forced to find ways to restrict traffic in busy streets if nothing else helps to reduce airborne pollutants.
      Nitrogen dioxide is the most dangerous of all nitrogen oxides, and its levels have not decreased, even though the total amount of nitrogen emissions caused by road traffic has been cut down by the use of catalytic converters on cars.
      Nitrogen dioxide is penetrates deep into respiratory passages, causing symptoms particularly in children and asthmatics. In high concentrations it causes bronchial compression.
     
Heavy traffic in particular generates nitrogen oxide emissions. The concentrations rise during rush hours as well as in the frost spells of the winter, and in the spring when airborne pollutants mix and disperse poorly.
      In the Greater Helsinki area, it has been decided already that a joint air quality monitoring programme will be carried out in cooperation with the region's municipalities and YTV.
      Environmental inspector Jari Viinanen of the City of Helsinki's Environment Centre believes that in order to reduce the amount of pollutants, certain measures including parking restrictions and the subsidies for of public transport will be required.
      "One bus always pollutes less than 30 passenger cars", he argues.
      Other ways to decrease the amount of pollutants would be to adopt more advanced cleaning techniques for exhaust gases or to change to less polluting fuels, such as natural gas.
      The exhaust pipe of a passenger car emits nitrogen monoxide which reacts with ozone producing nitrogen dioxide. On the other hand, a diesel catalytic converter emits more direct nitrogen dioxide.
     
The set limits for air quality are binding and they are to be reached by certain deadlines. The deadline for cutting airborne particles was already at the beginning of last year.
      The deadline for the reducing nitrogen dioxide is January 1st 2010. Based on the measurements in Helsinki's Hämeentie last year, the emissions of nitrogen dioxide reached 46 micrograms per cubic metre, while the maximum permissible limit for the annual average concentrations per hour could have been 40 micrograms. In the monitoring station of Mannerheimintie 5 the average was 43 micrograms.
     
On Thursday morning pollution levels were high in the Greater Helsinki area including Espoo. The concentrations of nitrogen dioxide were around 140 micrograms per cubic metre in Mannerheimintie during the morning rush hours. The afternoon was cloudy which reduced the concentrations.
      The maximum level for nitrogen dioxide is 200 micrograms. In Helsinki the emissions have very seldom exceeded this limit.
      The most hazardous pollutants are airborne particles, nitrogen dioxide, ozone, carbon monoxide, benzene, and sulphur dioxide.
     
This is already the second time for Helsinki to have to submit its account to the European Commission for the elevated particle emissions in its streets on some days. The city has already once promised to improve its street maintenance and to choose cleaner gritting sand in the spring.
      Nevertheless, compared with European metropolises, the air quality in the Greater Helsinki area is good.


Previously in HS International Edition:
  Helsinki under pressure from EU again over airborne dust (9.12.2005)
  Sudden and deep decline in air quality in Helsinki region (23.11.2005)
  Study shows serious airborne dust problem in Helsinki in recent months (6.5.2005)
  Poor air quality caused by cold weather, street dust, and exhaust fumes troubles Helsinki residents (17.3.2005)

Links:
  The Helsinki Metropolitan Area Council (YTV)
  City of Helsinki Environment Centre

Helsingin Sanomat