Air quality challenges now and in the future
The Helsinki metropolitan area is one of the cleanest metropolitan areas in Europe in terms of air quality. Concentrations of air pollutants in the Helsinki metropolitan area have generally decreased or remained stable over the long term, despite strong growth in population, traffic volumes and energy production.
Current air quality challenges
The most problematic air pollutants for air quality in the Helsinki metropolitan area are fine particles, thoracic particles, benzo(a)pyrene, nitrogen dioxide and ozone. The main emission sources in terms of air quality are:
- traffic, long-range transport and small-scale wood burning for fine particles;
- street dust for thoracic particles;
- small-scale wood burning for benzo(a)pyrene and
- traffic, especially diesel vehicles, for nitrogen dioxide.
The most problematic areas in terms of air quality are poorly ventilated busy street canyons, areas close to busy routes, and densely built detached housing areas where a lot of wood is used as an additional heat source.
The adverse effects on air quality caused by traffic exhaust gases have decreased in the Helsinki metropolitan area. In the busies places, the concentrations of nitrogen oxides in exhaust gases have fallen rapidly. This has been facilitated by the renewal of the car fleet and emission reduction technologies, as well as by the reduction of emissions from HSL’s bus fleet. Fine particle and benzo(a)pyrene concentrations have also decreased. The concentrations of thoracic particle have decreased in the long run thanks to street maintenance measures. Ozone concentrations have remained at the same level for a long time.
The EU limit values are not exceeded any more. However, the concentrations of nitrogen oxides, fine particles and thoracic particles exceed WHO air quality guidelines widely in urban areas. Exceedances of the target value of benzo(a)pyrene have not been measured lately. Ozone concentrations still exceed the health-based EU long term objective and WHO guidelines.
Future air quality challenges
Fine particles, thoracic particles, nitrogen dioxide, ozone and benzo(a)pyrene will continue to be challenges in the Helsinki metropolitan area even in the 2030s. Especially particle emissions from small-scale wood burning and street dust will remain problems in the future as well.
Health effects of air pollutants to decrease slightly in Finland in 2030
- Exhaust emissions from traffic and machinery will be significantly reduced.
- The amount of long-range transported particles will decrease slightly, but the risk of wildfires will increase.
- Wood burning and street dust will continue to be challenges in urban areas.
- The population is growing and ageing, and cities are becoming denser, resulting in more exposed people and groups sensitive to air pollutants.
Long-range transport of fine particles is decreasing
Long-range transport has a major impact on fine particle concentrations. Emission reductions of particles and particle-forming gases (sulphur dioxide, nitrogen oxides, ammonia and volatile organic compounds) implemented in Europe are reducing the long-range transport of fine particles.
In 2030, fine particle concentrations in the Helsinki metropolitan area will be below the EU’s annual and daily limit values. The concentrations will probably also be below the WHO annual guideline value. The WHO daily guideline value may be exceeded due to long-range transport or the accumulation of fireplace and local emissions in the breathing air in calm weather.
Street dust will remain a challenge for air quality in the future as well
It is difficult to estimate the development of street dust emissions. The population of the Helsinki metropolitan area is projected to grow strongly. As a result, traffic volumes will also grow, increasing street dust emissions. The electrification of transport does not reduce the amount of street dust. On the other hand, street and road maintenance measures can significantly reduce street dust emissions. Studded tyres, their characteristics and share in traffic flow also have a major impact on street dust emissions. Lowering driving speeds can also reduce the amount of street dust.
The prevention of street dust emissions has been developed in the Helsinki metropolitan area in recent years, and measures are still needed to control the concentrations of thoracic particles. The prevention of dust problems caused by construction sites needs to be developed as well.
The daily limit value for thoracic particles will not be exceeded in 2030. Health-based WHO daily guideline values will continue to be exceeded in many urban areas and in the busiest traffci environments.
Emissions from fireplaces remain a challenge
Residents favour wood as an energy source for climate reasons and to save electricity, and at the same time, the urban structure is becoming denser in detached housing areas as well. Wood burning has a significant impact on the air quality in densely built detached housing areas. The amount of wood used in detached houses in Finland has been growing steadily since the 1980s, and HSY estimates that the amount of wood used in detached houses will remain unchanged or increase in the Helsinki metropolitan area.
New heat-storing fireplaces and wood-burning stoves have lower emissions than the average fireplaces in use. Emissions from new boilers and fireplaces sold after 2020–2022 are controlled by ecodesign regulations (EU 2015/1189, EU 2015/1185). The impact of the regulation on the emissions of fireplaces is slow due to the long service life of heat-storing fireplaces and the slow renewal of the equipment stock.
The target value for benzo(a)pyrene is unlikely to be exceeded in 2030 in the Helsinki metropolitan area.
Concentrations of nitrogen dioxide and fine particles caused by road traffic are declining
The specific emissions of exhaust air pollutants from new vehicles will decrease in the future due to stricter exhaust emission regulations. Total emissions will also decrease, but the development will be slowed down by, among other things, the slow renewal of the car fleet and the growth in traffic volumes. The phase out of fossil fuels and the consequent proliferation of electric cars would be effective in reducing emissions, but so far the number of electric cars has increased quite slowly.
The city structure will be made denser for climate reasons. As the need for mobility decreases, so do emissions. However, in terms of air quality, this may lead to city structures that weaken the mixing and dilution of air pollutants and thus reduce the air quality. For example, turning Helsinki’s busy entry routes into city boulevards, where housing and workplace construction has been assigned to the immediate vicinity of routes, threatens to increase congestion and reduce the air quality unless the volume of car traffic can be curbed at the same time.
The EU limit values for nitrogen dioxide are not exceeded but health-based WHO daily guide line is in danger to be exceeded in all busy traffic monitoring sites. High traffic volumes and congestion can cause high concentrations in narrow and high street canyons.
Ozone continues to enter the region
Long-range transport has a major impact on ozone concentrations. Its concentrations are difficult to influence through local action, and reducing them requires international cooperation. Emissions of ozone-forming compounds are declining in Europe. This has not led to a corresponding decrease in concentrations, as ozone concentrations do not depend directly on emissions of ozone-forming compounds, but are influenced by many factors.
Ozone concentrations are likely to continue to exceed the EU health-based long-term objectives and WHO guide lines in 2030.