Information
Editors
Indoor Air Pollution
Causes and sources of emissions
- Clean and fresh indoor air is an important factor promoting wellbeing and working ability.
- In Finland, exposure to the primary indoor air pollutants is lower than in Europe as a whole, on an average, except for radon. Yet, indoor air problems are still common and have significant economic effects.
- The severity, causes and consequences of such problems vary greatly.
- There may be hundreds of pollutants in indoor air which, if present in high concentrations, may cause mostly transient symptoms, but there are also individual pollutants that increase the risk of permanent disease.
- Adverse effects of indoor air pollutants have been detected in large population surveys, and the mostly strict guidelines drawn up based on such studies are aimed at preventing these adverse effects. On the individual level, however, it is very difficult and often impossible to assess the association.
- Indoor air experienced as good is important for work efficiency and for comfort. Indoor air questionnaires may be used to assess the severity of indoor air problems in buildings. Nevertheless, symptoms alone cannot be used as a measure of the state of a building or of indoor pollutants because the symptoms are unspecific and depend on many factors, some of them psychosocial.
- The Finnish Indoor Air and Health Programme 2018-2028 coordinated by the Finnish National Institute for Health and Welfare aims to reduce symptoms linked to indoor air http://thl.fi/en/web/thlfi-en/research-and-expertwork/projects-and-programmes/the-finnish-indoor-air-and-health-programme-2018-2028.
Diseases and symptoms linked to indoor air
- The most significant pollutants increasing morbidity are tobacco smoke and fine particles (cardiovascular diseases), asbestos and radon (cancer), and moisture damage (asthma).
- There is no standard medical definition of indoor mould / indoor air disease (sick building syndrome).
- Very many kinds of pollutants in indoor air may affect comfort and cause symptoms.
- The symptoms are typically respiratory or mucosal.
- Reporting of symptoms depends on the presence of factors worsening the quality of indoor air and, on an individual level, on attitudes, expectations and collective factors.
- Some people may develop a long-term susceptibility to symptoms (environmental sensitivity) reducing their functional capacity and ability to work.
- Symptoms typically stem from various organ systems and appear in many buildings with clean indoor air.
- Studies of people with multiple chemical and electricity sensitivity show sound evidence that the symptoms are not due to exposure to a certain factor but associated with an awareness of exposure to an agent believed to be detrimental.
The most significant adverse indoor factors
- Pollutants in buildings may come from outdoor air, the soil, building structures and many indoor sources, such as building or furnishing materials or human activity.
- Ventilation has a decisive influence on concentrations in indoor air.
- Too warm and dry indoor air increases respiratory and mucosal symptoms.
- At the typically low concentrations in indoor air in Finland the associations between pollutants and adverse health effects are mostly weak and detectable primarily in large population surveys.
- Fine particles (PM2.5; PM10) and chemicals attached to them mainly arise in burning processes. They either travel inside from outdoors or arise indoors (smoking, indoor wood-burning, candles). Exposure to fine particles increases the risk of cardiovascular and lung diseases (COPD, asthma) and lung cancer, and increases symptoms particularly in people with cardiac or respiratory disease.
- The adverse effects of passive smoking resemble those of active smoking or fine particles.
- Radon is an odourless and tasteless radioactive gas released from soil. It is a risk factor for lung cancer, particularly in smokers.
- Moisture damage in buildings increases the risk of respiratory symptoms, in particular, and of asthma, particularly in childhood.
- Moisture damage varies widely in severity and is associated with many types of exposure.
- Even though microbial growth is the most probable factor causing health effects, evidence of this is weak and contradictory. There is no evidence that microbial toxins play a significant role, either.
- Industrial mineral fibres, such as glass fibres (glass wool) and stone fibres (mineral wool) may cause irritation symptoms of the skin, eyes and respiratory tract. The use of asbestos has been forbidden in Finland since 1993. Asbestos causes asbestosis and cancer. Asbestosis, see Asbestos-Related Diseases.
- Allergens (pollen, dog, cat, etc.) may cause allergic and respiratory tract symptoms in those sensitized to them (IgE-mediated sensitization) but avoiding these has little significance in preventing allergic diseases.
- There may be hundreds or thousands of volatile organic compounds (VOC) in indoor air. They are typically measured as an indicator of indoor air problems.
- In homes and offices, levels are usually clearly lower than in industrial environments and considerably below the absolute threshold.
- The odour threshold of the compounds is in most cases lower than the absolute threshold, and any adverse effects consist mainly of odour perception.
- High levels may cause transient mucosal or respiratory tract symptoms. Individual compounds (such as formaldehyde, TXIB, 2-EH, naphthalene or styrene) have also been linked to morbidity.
- The comfort and noise level of the indoor environment and many psychosocial factors affect reported symptoms.
Increased symptoms in certain buildings
- Indoor air in buildings should be healthy and safe. In addition, users should be able to trust that it is healthy.
- The owner of the building is responsible for healthy indoor air of homes, schools and other premises, and this is supervised by health protection authorities. At workplaces, the employer, with the help of occupational health care, is responsible for healthy indoor air, and this is supervised by occupational safety and health authorities.
- The preventive action limits set for indoor pollutants and conditions in homes, schools and other premises are usually defined by relevant authorities or in the legislation. In Finland, these limits are defined in a decree and they are quite strict. Therefore, exceeding these action limits does not necessarily mean that the pollutant or condition is relevant as a cause of symptoms.
- In Finland, action limits are set for temperature, humidity, air velocity, ventilation, many volatile organic compounds, particles, fibres, tobacco smoke, microbes and noise, for example.
- Equivalent guidelines exist for workplaces.
- In difficult situations, there are often multiple problems, such as poor ventilation together with some low level pollutants. The situation may be complicated by odours experienced as unpleasant and by the thermal environment, by mistrust on the part of the users and, on the other hand, by the significant economic impact of structural solutions.
- The occurrence of symptoms cannot be used as a direct measure of the condition of the building or of indoor air pollutants. Repair decisions should be based primarily on objective data on the condition of the building.
- A multiprofessional, targeted approach, holistic consideration of the situation and regular, open communication are essential for successful solution of problematic situations.
Patients with symptoms associated with indoor air
- Regardless of their aetiology, observed symptoms and diagnosed diseases must be treated according to conventional therapeutic guidelines.
- Symptoms should not be dismissed. Meticulous differential diagnosis is an important part of the investigations because many diseases produce similar symptoms to indoor air problems.
- Severe, diverse symptoms without detection of significant problems in indoor air quality may suggest long-term susceptibility to symptoms (environmental sensitivity), which is a functional disorder.
- The patient may experience even mild symptoms as threatening. The doctor should explain the nature of the symptoms clearly, provide evidence-based information on adverse health effects of indoor air problems, support investigation of indoor air problems, as far as possible, and provide instructions for treating the symptoms.
- No position should be taken on the role of indoor air in the building in the patient's symptoms or disease, unless a reliable investigation of the situation in the building has been conducted. Nevertheless, assessment of the association will always be uncertain.
- The doctor's task is to support health and recovery and the patient's possibility to continue in his/her work.