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Indoor air investigations

Indoor air investigations are usually based on establishing the reason for a building’s indoor air problems, or acquiring preliminary information for a renovation project.

If indoor air problems are suspected in a building and cannot be solved through adjusting the ventilation and cleaning, for example, the City will examine the building in more detail.

The investigations will be ordered from external investigative consultants chosen as a result of a competitive tendering process. The City applies commonly accepted investigation methods. Strict quality criteria are in place for the researchers and research methods, and the contents of the investigations are defined case-specifically.

Usually, the investigation report is complete some 4–6 months after the investigation starts. The report will be used as a basis for the plan of the necessary repairs.

What do the investigations comprise?

There can be several simultaneous factors that can affect the quality of indoor air, which is why the investigations must be sufficiently extensive and the building must be examined as one unit. Indoor air investigations can measure and review the following matters, among other factors:

  • structural risk analysis: structure types and their moisture technical functional modes
  • reasons for and extent of moisture damage through measures such as moisture measurements, opening structures, and microbial analysis of material samples
  • indoor air temperature and humidity and the temperature of supply air
  • the cleanliness of the ventilation system, quantity of air and the ‘flushing out’ process of the premises, i.e. the distribution of clean supply air in the rooms
  • condition of the building services systems
  • pressure differences between outdoor air and the interior, for example between the crawl space and rooms
  • carbon dioxide content of the indoor air
  • concentrations of chemical compounds in materials and indoor air
  • occurrence of mineral wool fibres
  • harmful substances in materials, such as asbestos and PAH compounds.

The key guidelines for indoor air investigations and assessments:

Rakennusten kosteus- ja sisäilmatekninen kuntotutkimusopas 2016 (Guidebook for the condition surveys of buildings’ moisture and indoor air technology)

Decree on housing health 545/2015

Application manual for the decree on housing health (National Supervisory Authority for Welfare and Health 2016)
Indoor air classification (Sisäilmayhdistys 2018)

The Finnish Institute of Occupational Health’s reference values (in Finnish)

Assessment of exposure conditions

If necessary, an assessment of exposure conditions can be carried out alongside the condition surveys or after they have been completed. Its purpose is to assess whether the indoor air conditions in the premises deviate from those of ordinary conditions, e.g. whether they have more indoor air contaminants or sources of contaminants than similar, ordinary operational environments.

The assessment is primarily based on technical surveys of indoor air and moisture conditions. It considers the extent, severity, location and potential indoor air connection of the contaminant sources, as well as other factors related to the spreading of contaminants, such as the functionality of ventilation and pressure differences. Exceeded reference values alone do not allow for conclusions to be drawn on the exposure conditions and their significance.

If an abnormal condition is likely or highly likely in the building, the plans for repairs and measures securing the use of the premises will be started without delay.

Radon measurements

The City of Helsinki reviews the radon concentrations at its workplaces. These measurements are based on the Radiation Act, according to which an employer has the duty to review its employees’ exposure to radon.

The radon measurements at the City of Helsinki’s workplaces are carried out in close cooperation with the City’s various divisions. The Urban Environment Division’s Indoor Air Team is in charge of coordinating the measurements, which are implemented by the site’s contact person. The measuring process has been made as easy as possible with detailed instructions.



 19.08.2021 18:53