Air quality improves in Helsinki harbours

13.5.2022 15:40:30

Air quality in the harbours is mainly affected by emissions from car traffic and ship traffic. According to the measurements of the Helsinki Region Environmental Services Authority (HSY), the amount of air pollutants has decreased notably over the years.

Silja Serenade at South Harbour.
HSY monitors the development of air quality in harbours. In the harbour areas, air quality is mainly affected by emissions from cars and ships. However, the seaside being open and well-ventilated improves the air quality.

Harbour air quality is mostly good

Helsinki Region Environmental Services Authority (HSY) has monitored the air quality of harbour areas in Katajanokka, West Harbour, Eteläranta and Vuosaari for several years. The location of the measurement station varies each year. In 2021, the station was at Katajanokka. The air contained particulate matter, such as street dust, fine particles, sulphur dioxide, and nitrogen oxides, meaning exhaust emissions.

“Emissions from ship traffic and car traffic in the harbour areas have clearly decreased, which can also be seen in air quality. For example, sulphur dioxide concentrations have decreased notably as a result of emissions standards for ship traffic becoming stricter,” says Saija Korhonen, HSY’s air quality specialist.

In 2021, the annual sulphur dioxide concentrations at Katajanokka were at 0.8 micrograms per cubic metre (µg/m3). In 2013, before the latest changes to the emissions standards, the concentrations were at 3.2 µg/m3. Besides emissions from ship traffic, the sulphur dioxide emissions from energy production have also been reduced.

Annual nitrogen dioxide concentrations have also decreased in Helsinki harbours in the long term. The reduction in concentrations is at least partially caused by the car population becoming increasingly modern and exhaust emissions becoming cleaner. Another reason is the COVID-19 pandemic reducing the number of ship passengers and the volumes of car traffic, which can be seen in the results for 2020 and 2021.

“In the last few years, the Port of Helsinki has adopted onshore power supply in several harbours, which will also be expanded in the coming years. Onshore power supply reduces the emissions generated significantly while ships are berthed,” says Andreas Slotte, head of sustainable development at the Port of Helsinki.

Last year, the World Health Organization (WHO) published increasingly strict threshold values for various air pollutants. In the Helsinki Metropolitan Area, these values are exceeded in various environments, including the harbours in terms of nitrogen dioxide and fine particles.

Ships’ arrival and departure times affect daily fluctuation of pollutants

The air pollutant concentrations in harbours vary by the ships’ arrival and departure times. In Katajanokka, for example, the concentrations of nitrogen dioxide increase in the morning and evening.

“The air pollutant concentrations show clearly when the ships have arrived and departed: the concentrations fluctuate based on the schedules of incoming and outgoing traffic. The same fluctuation can be seen both on weekdays and at weekends,” Korhonen says.

Information about air pollutants:
• Nitrogen oxides (NOx) originate from traffic emissions, particularly from diesel vehicles and heavy traffic. Of nitrogen oxides, nitrogen dioxide is the most common cause of health hazards. In high concentrations, it contracts the bronchi and increases respiratory symptoms among children and persons with asthma, in particular.
• Sulphur dioxide (SO2) outdoors mainly originates from energy production and ship emissions. Sulphur dioxide emissions have decreased significantly over the past decades, which is why concentrations outdoors are low these days.
• Inhalable particles (particulate matter, PM10) mainly come from street dust raised by traffic, which may pose a health hazard. Increased amounts of street dust weaken the wellbeing of persons with respiratory illnesses, in particular.
• Fine inhalable particles (PM2.5) mainly come from emissions caused by traffic and the burning of wood. They also traverse to the Helsinki region from outside Finland. These particles are considered especially hazardous to health since they can enter the lungs’ most peripheral parts.
• The groups who are the most vulnerable to health hazards caused by air pollutants are small children, seniors, and persons with respiratory or cardiovascular illnesses.

• Air pollutant concentration trends in the Helsinki Metropolitan Area: 
• Emissions trends from various sources in the Helsinki Metropolitan Area: 
Air quality publications by HSY
Air pollutant concentrations as open data