Air quality in different environments

Two ice fishers in the foreground with the city behind them on a sunny day. The ice is covered by a layer of snow.

The air quality varies in different areas of the Helsinki metropolitan area. It is influenced by various emission sources, the built environment, geographical features, and weather conditions.

Air quality is affected by car traffic in the vicinity of roads and streets, by wood burning in detached house areas, by ships and related traffic in the vicinity of harbours, and by airport operations and related traffic within the vicinity of the airport. Other activities that affect the air quality in the surrounding area include construction sites, crushing plants, asphalt mixing plants, wastewater treatment, waste treatment and industry as well as wildfires. The air quality in the Helsinki metropolitan area is also slightly affected by local energy production. In addition, air pollutants are transported to the area with air currents from outside the region and the country’s borders.

The Helsinki metropolitan area is mostly flat and low-lying territory. The flat topography and open location by the sea promote the mixing and dilution of air pollutants. In urban environments, the city structure affects the spread of air pollutants. In unfavourable weather conditions, such as mornings with little wind, higher levels of air pollutants accumulate.

Busy area

In the Helsinki metropolitan area, traffic exhaust gases reduce the quality of breathing air the most, because they are discharged close to our breathing height. Traffic increases the quantity of fine particles, nitrogen dioxide and street dust. A road has a significant impact on the air quality in the surrounding area when it is used by more than 10,000 vehicles per day. Emissions are highest right next to a traffic route, and every metre further away from it improves the air quality. Even just a block away from a main route, the air is cleaner, and your exposure to fine particles, for example, is reduced by approximately 25%. Traffic emissions affect the environment up to a distance of 150–200 metres. Traffic noise also indicates emissions: if the noise bothers you, there are pollutants from traffic in the air as well.

Street canyon

A street canyon is a street lined on both sides by tall buildings that prevent the spread and dilution of air pollutant emissions from traffic. Dilution is weakest in a situation where the buildings form a continuous, impermeable wall. The buildings prevent air pollutants from spreading to the courtyards, but reduce the air quality on the street side. Exhaust gases can spread through openings and open points. The air is cleaner in the courtyards and on the upper floors than in the street.

Downtown area and regional centres

Air pollutant levels are usually highest in city centres. If you move about or live in downtown and other busy areas, you will be exposed to air pollutants. However, buildings prevent the spread of air pollutants to courtyards, and thus the air is cleaner in the courtyards and at the height of the upper floors than at street level.  

Detached house areas

The air quality in detached house areas is usually affected by the use of fireplaces and by street dust.

The use of fireplaces increases the concentration of fine particles in detached house areas and can reduce the air quality from time to time. Wood is burned in approximately 80% of the detached houses in the Helsinki metropolitan area. Even though the use of wood as the primary heating method is rare in the area, emissions from fireplaces reduce the air quality, as there are many detached houses close together. Emissions from wood burning cause significant health effects because the emissions are generated in residential areas and are instantly in the breathing air of the area. The use of fireplaces is concentrated on times when people are at home or in their yard, and are thus exposed to the emissions. On days with freezing weather and little wind, the smoke will hang in the air in the yard and find its way into homes. 

Construction sites

Construction sites are significant local sources of dust and reduce the air quality in the surrounding area from time to time. Large construction sites can cause dust nuisance over a wide area for several years. With construction site traffic, dust can also be transported to nearby streets and roads. Emissions from the machinery can also have a local impact on air quality. Efforts are made to limit the emissions from construction sites to reasonable levels, and their negative effects are generally short-term.

Construction-related activities, such as rock crushing and excavation, can cause dust and noise nuisance in the surrounding environment. For activities that cause significant harm, regulations can be issued to reduce emissions, for example, in noise notification decisions, with the aim of keeping the environmental damage reasonable.

Areas adjacent to harbours, airports, industry and energy production

Ship emissions reduce the air quality locally and depending on the weather. When congested, traffic to harbours can reduce the air quality on nearby streets. Harbour machinery also causes emissions. Harbours are located in well-ventilated areas, and emissions tend to be diluted efficiently.

In the Helsinki Airport area, emissions into the air are caused by a number of different activities and operators, such as air traffic, ground equipment in the airport area, the airport’s own energy plants, as well as pick-up and drop-off traffic. Aircraft and area operations affect the air quality in and near the airport area. Kerosene evaporates into the air when refuelling aircraft, which can cause odour nuisance in the air at and in the immediate vicinity of airports. Emissions from pick-up and drop-off traffic reduce the air quality locally.

There is little industry in the Helsinki metropolitan area, and thus the impact of industry on the quality of breathing air is also low. Emissions from industry are regulated in environmental permits as well as registration and notification procedures. Efforts are made to limit the emissions to reasonable levels.

Emissions from energy production are discharged from tall chimneys, so they spread over a wide area and generally do not cause environmental damage locally.

Areas adjacent to waste treatment

There are operations at waste treatment sites that cause odours and dust. For example, total reduced sulphur compounds are released into the air from the final waste disposal site as well as from the treatment of biowaste and sludge at the Ämmässuo eco-industrial centre. Total reduced sulphur compounds reduce comfort even at low concentrations, due to their unpleasant odour. The concentrations are highest in the vicinity of the emission source and spread with the wind. Elevated concentrations occur in the air for short periods of time.

Wastewater treatment and wastewater pumping stations can also cause unpleasant odours in the surrounding area. Both waste treatment and wastewater treatment are subject to obligations set in environmental permits, and their operations, emissions and environmental impacts are controlled and monitored.

Cleanest areas in terms of air quality

Seaside

Air pollutants can be better diluted in open environments. Areas near the sea are well-ventilated and the wind brings with it clean air. Ship emissions and traffic to harbours can reduce the air quality in the surrounding area from time to time.

Parks and outdoor recreation areas

The air is the cleanest far away from busy roads and other emission sources. Favour parks and outdoor recreation areas for outdoor activities and jogging.

 

Contact information of cities’ environment centres:

Updated : 08.12.2022 16:38