Helsinki could ban driving on days of poor air quality

The Mayor of Helsinki may soon have the authority to ban the use of private cars in central Helsinki on days of very poor air quality.
      Such a move would require that the content of nitrogen oxides in the air would have been at a high level for several consecutive days, and that a certain level in the air would be exceeded.
      "Such a situation is very unlikely. It is more typical for air quality to be poor because of nitrogen dioxide for just a few hours", says Helsinki environment inspector Jari Viinanen.
     
Helsinki has drawn up guidelines for sudden spikes in pollution. The most stringent measures are reserved for situations in which nitrogen oxides resulting from transport emissions reach a high level.
      Especially in wintertime there can be large amounts of nitrogen dioxide in the air, if cold air is trapped underneath a layer of warmer air hovering above, and the emissions do not have a chance to dissipate. In such situations, heart patients, asthma patients, and small children can suffer symptoms.
     
In the new contingency plan, street dust and smoke are also taken into consideration.
      There are high levels of street dust in the air especially in springtime, when the content of airborne particles often exceeds the maximum acceptable levels.
      If there is too much street dust in the air, the streets are sprayed with a mild saline solution which can keep the streets damp for several weeks. However, no restrictions on traffic are planned for dust.
      With respect to smoke, Helsinki is preparing for wildfires and controlled burn-offs in Russia and other nearby areas, which sometimes send smoke over Helsinki.
      In such situations, there is little that the city can do beyond warning residents of the situation and its likely duration.


Previously in HS International Edition:
  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)
  Helsinki lags behind other large cities in discouraging use of cars in centre (24.9.2007)
  Airborne dust season begins early in Helsinki area (16.3.2007)
  Street dust may weaken air quality in Helsinki noticeably (14.3.2006)

Links:
  Helsinki considers restrictions on car traffic because of increased air pollutants (27.1.2006)