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Air quality

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The air quality in Helsinki has improved over the last few decades, and it is fairly good at an international level. However, exhaust emissions from traffic, street dust and emissions from burning wood in domestic fireplaces continue to be harmful to people’s health and comfort. In autumn 2021, the World Health Organization (WHO) published new threshold values for air pollution based on the latest health research. These threshold values are significantly lower than before, and they are largely exceeded even in Helsinki, especially in terms of nitrogen oxide, inhalable particles and small particles.

Helsinki City Strategy aims to improve the quality of the city environment and promote safety and comfort within it. Focusing on the electrification and further sustainability of transport will advance the City’s climate goals, as well as air quality. The purpose of the City’s Air Quality Plan is to reduce nitrogen dioxide emissions from traffic so that the emissions will not exceed the threshold values. In addition to decreasing exhaust gas emissions, the plan’s other focus areas are street dust and the small-scale burning of wood. The plan contains 48 measures to be implemented in 2017–2024. 

Nitrogen dioxide concentrations on the decrease

In the past years, the annual EU limits for nitrogen oxide have not been exceeded in Helsinki. The exhaust gas emissions from traffic have decreased thanks to advanced vehicle technology and electrification. Replacing buses with lower-emission ones has played a key role. However, the nitrogen dioxide concentrations may rise at times on busy and chasm-like streets. Last year, the concentrations across the board were higher than in 2020, during which the air quality was improved by the decrease in traffic volumes due to the COVID-19 pandemic and a very mild winter.

Image 7. The nitrogen dioxide concentrations were slightly higher than last year.

Street dust can be controlled by promoting studless tyres

In addition to direct exhaust emissions, traffic also produces street dust. The limit values for street dust, i.e. inhalable particles, have not been exceeded in Helsinki in recent years, but the risk of exceeding them still remains. The dust volumes in the spring are also significantly affected by the weather conditions and snow volumes in the spring and winter. In 2021, the situation with street dust was more difficult than in the previous year.

For several years now, Helsinki has participated in research collaboration projects on the formation of street dust and measures to reduce it. The measures that have proven to be the most effective have been adopted in practical street maintenance. In addition to these, the City aims to promote the use of studless friction tyres through communication, as these tyres wear out the street surfaces much less than studded tyres. The City will purchase only studless tyres for its own passengers cars and vans. In autumn 2021, the City prepared a pilot on banning studded tyres that will begin on the Lönnrotinkatu street in autumn 2022.

The impact of large construction sites on local particle concentrations has been identified as a challenge. In 2021, measurements were carried out in Jätkäsaari like in previous years. Efforts are being made to prevent dust emissions in cooperation with contractors, and new methods were developed in the HOPE project coordinated by Helsinki, among others.

Image 8. Street dust concentrations increased somewhat from the previous year.

Using communication to reduce emissions from burning wood

In dense detached house areas, the air quality is decreased by the small-scale burning of wood in fireplaces and sauna stoves. In the Helsinki Metropolitan Area, small particle emissions from fireplaces are even greater than those from traffic. Efforts are being made to find ways to decrease emissions from the small-scale burning of wood by means such as research projects in which the City is involved. Residents have also been extensively provided with information on ways to significantly influence how cleanly wood burns.

Eyes on the future

Thanks to advancements in vehicle traffic technology and the electrification of vehicles, direct exhaust emissions have decreased. However, street dust will remain a challenge, which is why the use of studless tyres and dust control require investments. It has even been estimated that electric cars may produce more dust emissions because they are heavier. In addition to this, air pollution is diluted less as the city structure grows denser. Large construction sites have been identified as major sources of street dust, and controlling their dust emissions requires further development. Burning wood in the fireplaces of detached houses will not decrease in the near future, which is why we must make an effort to control its emissions.