Impact of indoor air on health

Good indoor air promotes good health, work performance and learning. In addition to good indoor air, an indoor environment that supports health and wellbeing requires comfortable and functional facilities that are fit for the intended purpose.

On this page

High-quality indoor air in city facilities is essential for the wellbeing and comfort of staff and Helsinki residents. Good indoor air increases productivity at work and improves learning outcomes at school, for example.

Prerequisites for a pleasant indoor environment include:

  • Correct temperature
  • Suitable atmospheric humidity
  • Neutral scents
  • Good ventilation
  • Lack of draught
  • Good acoustics and low noise levels
  • Correctly selected low-emission materials
  • Cleanliness and ease of cleaning
  • Structures that are in good condition

What can reduce indoor air quality?

Indoor air quality can be affected by various impurities or conditions. These may also cause inconvenience or symptoms to the users of the facilities. In normal working and office environments, indoor air impurities mostly cause mild symptoms that will pass when the person does not spend time in the facilities or the building defects are repaired.

Symptoms or conditions related to indoor air may be caused by the following, for example:

  • Wrong temperature
  • Draught
  • Dry indoor air
  • Defective ventilation
  • Excessive number of users
  • Humidity and microbial damage
  • Dust and fibres
  • Insufficient cleaning
  • Chemical emissions from construction and interior decoration materials
  • Cigarette smoke
  • A variety of odours
  • Airborne allergens such as pollen or animal dust in the indoor air
  • Fine particles and other outdoor air impurities

What kind of symptoms can poor indoor air cause?

Symptoms associated with poor indoor air include:

  • Irritation of the eyes, respiratory system and skin
  • General symptoms (e.g. fatigue or headaches)
  • Difficulty concentrating
  • Respiratory symptoms (e.g. upper respiratory tract symptoms, coughing or wheezing)

For example, inadequate ventilation or indoor air that is too dry or too warm can cause general symptoms such as headaches and fatigue. The symptoms caused by poor indoor air quality can impair your ability to work and learn.

The symptoms are the sum of many factors and vary between individuals based on factors such as their immunity, perceptions of risks, general state of health, lifestyle and social factors. This is why only some of the people spending time in a room may show symptoms. Symptoms can also occur even if no impurities are detected in the facilities. The cause of the symptoms should always be investigated by the health care services so that the person can be helped in the road to recovery.

Many different factors can cause highly similar symptoms, which is why symptoms alone are not enough to determine what is wrong with a building. The starting point for the investigation into an indoor air issue should always be sufficiently comprehensive condition surveys. Many factors that deteriorate the quality of indoor air can be addressed by means of maintenance measures and cleaning, and by ensuring adequate and effective ventilation.

Link between indoor air impurities and diseases

Some indoor air impurities are associated with a risk of disease if the exposure is intense and prolonged. Unrepaired moisture and microbial damage, especially if it is extensive, is one of the risk factors for asthma. Moisture and microbial damage can also make other respiratory symptoms worse. Any observed damage must be repaired and its causes investigated, regardless of whether the people using the building are experiencing symptoms.

The main causes of indoor air-related health hazards and the risk of illness in Finland are:

  • Fine particles from outdoor air (risk factors for cardiovascular disease)
  • Cigarette smoke (a risk factor to several diseases, such as cancer)
  • Radon (a risk factor for lung cancer)
  • Moisture damage (a risk factor for asthma)

In addition to the impurities mentioned above, asbestos in indoor air is a risk factor for lung cancer. PAHs (polycyclic aromatic hydrocarbons) in indoor air are also linked to an increased cancer risk. The health effects of all impurities depend on the intensity and duration of the exposure, i.e. low or normal concentrations do not necessarily increase the risk significantly when compared to other risk factors for various illnesses.

Tools to assess indoor air quality and the severity of symptoms

We use a range of tools and approaches to investigate symptoms related to indoor air and perceived indoor air quality, to assess indoor conditions and to evaluate the health effects.

The perceived indoor air quality and the symptoms experienced by users can be investigated with a variety of questionnaires, such as:

  • A condition questionnaire based on a condition survey guide prepared by the Ministry of the Environment
  • An indoor air questionnaire for pupils developed by the Finnish Institute for Health and Welfare
  • A workplace indoor air questionnaire developed by the Finnish Institute of Occupational Health

However, in solving indoor air issues, priority should be given to a sufficiently extensive structural engineering survey and the identification of possible sources of impurities.

A condition assessment by a building health expert may be part of the indoor air survey. It is used to determine whether the conditions in a building or a specific room are abnormal. The assessment takes into account the likelihood, amount, quality and duration of exposure to impurities and hazards.

The health significance of a building is assessed by an occupational health physician based on the assessment of the conditions in the building or room by a building health expert. It also takes into account the health of the persons using the building (e.g. symptoms, illnesses and absenteeism). It also considers factors related to the use of the facilities (e.g. duration of exposure, working conditions and special characteristic of the job). There is no single measurement or quantification method for reliably assessing the significance of a building to people’s health.