Particulate matter (PM10 and PM2.5) and nitrogen dioxide (NO2) are the most important components of local air pollution. Other pollutants such as sulphur dioxide (SO2), ground-level ozone, carbon monoxide (CO), polycyclic aromatic hydrocarbons (PAHs) and benzene can also contribute to poor local air quality.

National targets and limit values exceeded

Norway has national targets for concentrations of particulate matter, NO2, SO2 and benzene. Most towns will miss the national targets for these substances by a considerable margin in 2010. In 2008, no exceedances of the limit value for particulate matter laid down by the Pollution Regulations were recorded, but this level was exceeded in 2009 in Trondheim.

Although there is a downward trend, further action needs to be taken to achieve the national target for particulate matter.

The health risks associated with local air pollution depend on the concentrations of pollutants and exposure time.

In Norway, it is mainly people with asthma and respiratory complaints or who suffer from cardiovascular disease who experience health problems caused by local air pollution. Children and young people, pregnant women and the old are also particularly vulnerable groups.

It is difficult to estimate the scale of health problems caused by local air pollution because knowledge of the links between exposure and ill-health/mortality is limited and there is a lack of data from Norway. 

Health risks greatest for particulate matter and NO2

In Norway's largest towns, particulate matter is the air pollutant that poses the most serious health risk, although NO2 is also a significant factor. Exposure to these substances increases the frequency of various types of respiratory complaints. Particulate matter can also cause cardiovascular disease and higher mortality.

Particulate matter consists of particles of such small size that they can be inhaled. The largest of them are stopped in the upper airways, but smaller particles with a diameter of less than 10 μm (called PM10) can penetrate deep into the lungs and are much more harmful.

The maps below show the loss in life expectancy attributable to exposure to fine particulate matter with a diameter of less than 2.5 μm (PM2.5) in Europe. The upper map is based on figures for 2000, and shows that the population in central Europe was most at risk. The lower map shows the forecast for 2020, by which time a considerable improvement is expected as a result of new legislation and action to improve local air quality.

Other pollutants also cause health problems

Other air pollutants are also harmful. SO2 can result in lung disease in healthy people as well as asthma patients. Benzene and other aromatic compounds such as PAHs are carcinogenic. CO reduces the capacity of the blood to transport oxygen and can cause headaches, nausea and other problems for heart patients.

Effects on ecosystems and vegetation

Local air pollution can be harmful to ecosystems and vegetation. NO2 and SO2 both contribute to acidification and eutrophication of lakes and rivers. CO and NO2 also contribute to the formation of ground-level ozone, which can damage vegetation and various types of materials. SO2 is also corrosive and erodes buildings and historical monuments.

Road traffic, domestic heating, long-range pollution and industry are all sources of local air pollution. Important factors influencing the emission trends from these sources include:

• economic growth, which results in a higher volume of traffic
• the siting of workplaces and homes, which influences transport needs
• road construction, which influences traffic volumes
• car ownership, which increases mobility
• the size of people's homes, which influences heating needs
• the technology available – abatement technology and efficiency improvements can reduce emissions

Economic growth, growing international trade, changes in land use patterns and rising private consumption all result in a larger volume of transport. A higher volume of transport reduces the effect of stricter emission limits and improved vehicle technology.

Road traffic is the dominant source of local air pollution, including particulate matter and nitrogen dioxide in exhaust emissions and asphalt dust worn off roads by studded tyres and nitrogen dioxide. Fuelwood use is another important source of particulate matter.

In Oslo, road traffic (exhaust and asphalt dust) is responsible for more than 70 per cent of the concentration of particulate matter near roads in winter, while 15 per cent comes from fuelwood use and 10 per cent from long-range air pollution. However, there are indications that emissions from road traffic and fuelwood use are declining.

Road traffic

Road traffic is an important source of particulate matter, though the proportions vary during the year and from place to place. A car with studded tyres can produce up to 100 times as much asphalt dust as one with non-studded winter tyres.

Vehicle exhaust accounts for more than 90 per cent of the concentration of NO2 near roads. Diesel vehicles produce higher emissions of both NO2 and particulate matter than petrol vehicles. Stricter European requirements have been introduced, and emissions from newer diesel vehicles are therefore considerably lower. However, heavy vehicles (which generally run on diesel) are still an important source of local air pollution, particularly NO2.

Fuelwood use, industry and long-range pollution

Wood-burning results in emissions of particulate matter and PAHs, and these can be substantial on cold days in winter, when many people are using wood-burning stoves. Other important sources of local air pollution are industrial emissions (especially particulate matter and SO2) and long-range transport of pollution from other European countries.

Norway has set national targets for the concentrations of various pollutants in outdoor air. In addition, there are legally binding limit values, which are the same as those that apply in the EU. These are set out in Chapter 7 of the Pollution Regulations. 

The municipalities are responsible for control and enforcement of legal requirements relating to local air quality. The municipalities have done a great deal to reduce local air pollution – for example by restricting the use of studded tyres, reducing speed limits and improving road maintenance.

Reducing emissions from road traffic and vehicles

Measures to reduce traffic are most effective when used in combination, for example road pricing combined with parking restrictions and improvements in public transport.

The Planning and Building Act can be used actively to influence the location of workplaces and housing and reduce the need for transport, and to encourage a switch to environmentally sound forms of transport. The Government has also issued national policy guidelines for coordinated land-use and transport planning under the Planning and Building Act.

Technical measures can be used to reduce emissions from individual vehicles. Emission limits for vehicles are being made steadily stricter, and the petrol and diesel quality is being improved.

Since 1 January 2005, all fuel sold for cars and heavy vehicles has had to be sulphur-free. The use of studded tyres can be discouraged through local regulations imposing a charge on their use. Emissions from road traffic can also be reduced by encouraging the use of alternative fuel types such as gas, hydrogen or electricity.

Reducing emissions from wood-burning stoves

Since 1 July 1998, new wood-burning stoves have had to meet legal standards for emissions of particulate matter. To encourage the replacement of old, polluting stoves, muncipalities can introduce a system of partial rebates. Such schemes have for example been introduced in Oslo and Bergen.Older stoves can also be retrofitted with equipment to reduce emissions.

Reducing long-range pollution

Long-range air pollution is being reduced through international agreements and EU directives. These include the Convention on Long-range Transboundary Air Pollution, the EU directive on emissions to air from large combustion plants, and the EU directive on national emission ceilings for certain pollutants (or NEC Directive).

Are we doing enough to reduce local air pollution?

The national authorities must help the local authorities to continue and intensify their efforts, and provide them with new instruments to use in this work. Good results depend on a comprehensive approach and close cooperation between local, regional and central authorities.

Without new measures and policy instruments, it will be difficult to achieve several of Norway’s targets and statutory limit values for air pollutants.