Miljøprojekt, 1097 – Status og perspektiver på indeklimaområdet

Status og perspektiver på indeklimaområdet

Summary

Insufficient knowledge about indoor climate
Project results

Insufficient knowledge about impacts of indoor climate

Danes spend 80-90 per cent of their time indoors and about 16 hours every day in their dwelling. The impacts that we are exposed to in the indoor climate are consequently of great important for our health and well-being. The risk management by the public authorities is difficult, because sufficient knowledge to make a proper risk assessment is only available for a few factors (radon, environmental tobacco smoke and asbestos).

Background and purpose

In the Danish Government's strategy for environment and health, the indoor climate has been identified as a focus area.

Indoor climate has great importance for public health, including comfort, productivity and diseases. Health may be influenced by many different factors, ranging from the surroundings, the construction of the building, its furnishing, lay-out and interior decoration, as well as behaviour, including smoke patterns, radon from the soil, and chemical emissions from consumer products to organisms, like house dust mites and moulds, and also particles from internal as well as exterior sources.

It can be difficult to get a picture of the existing knowledge about the indoor climate due to the many fields of expertise that each contributes with significant knowledge. Initiatives in this wide-ranging area are taken on many fronts, and there is a great need for an overall presentation in order to prioritize future public decision-making in the indoor climate area.

The purpose of this project is to provide an overview of indoor climate, in support of:

The elaboration of recommendations on how the public in general should act in order to achieve the best possible indoor climate.
Prioritizing by the public authorities across responsibilities, especially in relation to the need for regulation
Advice regarding areas where knowledge is specifically needed.

The investigation

The report was prepared by Lars Gunnarsen, the Danish Building Research Institute, Torben Sigsgaard and Nils Testrup Andersen, Department of Environmental and Occupational Medicine, University of Aarhus, Allan Linneberg, Research Center for Prevention and Health, Glostrup Hospital, Henrik N. Knudsen, Alireza Afshari and Carsten M. Pedersen, Danish Building Research Institute, John Christian Larsen and Elsa Nielsen, Danish Institute for Food and Veterinary Research. The report was edited by Lars Gunnarsen, who was also the project leader.

Moreover, senior researcher Jens Christoffersen at the Danish Building Research Institute has contributed with data on light, and chief medical doctor Christoffer Johansen, the Danish Cancer Society, has contributed with data on radiation.

The report was repeatedly discussed in a steering group consisting of Christina Ihlemann, Ove Nielsen, Finn Gyntelberg, Finn Gamél Christensen, Annlize Troest, Pia Juul Nielsen, Poul Bo Larsen, Christian Lange Fogh and Lea Frimann Hansen. Moreover, a draft report was presented and discussed at a workshop with about 40 Danish experts and interested parties.

Main conclusions

Unless otherwise stated, this report mainly concerns private homes where most and the most serious indoor climate problems are found. In response to the aim of the project, the recommendations can be summarized as follows.

Poor indoor climate may increase the risk of attracting infectious diseases, cancer, cardiovascular diseases and maybe allergy
Avoid moisturizing construction products for a prolonged time and mould growth in buildings
Smoking should not take place indoors
Ensure that outdoor construction products containing insecticides are not used indoors
Especially persons suffering from allergies suffer from a poor indoor climate
When selecting construction products, it is important to select products with low emissions of odorous compounds as well as other adverse chemical compounds
Many ventilation systems should be better operated and maintained.

Authorities are recommended to prioritize the following:

Targeted information about how to behave to obtain good hygiene at home
Improved guidelines for and monitoring of the indoor climate quality, especially in homes
To identify homes with especially high radon concentrations, and to reduce the exposure.
To investigate the need for reduction of the exposure to formaldehyde, benzene and carbon dioxide in the indoor climate.

Knowledge is needed about how we are affected by the indoor climate, especially in the following fields

We need a comprehensive investigation if the importance for public health of the indoor climate in dwellings
We need to develop new knowledge about the possibilities for reducing annoyance caused by ventilation systems
We need to examine the health effects of exposure to particles indoors from ventilation and the possibilities for reduction of exposure
We need to investigate the importance of exposure through house dust to phthalates, PBC, brominated flame retardants and both old and new insecticides
We need a wider understanding of the significance of moisture and the resulting biological and chemical processes in the indoor climate for the prevalence of annoyance, symptoms, asthma and allergy
Concerning occupational health and the indoor climate we need to know more about:
Annoyance and productivity in open plan offices

Well-being and learning in relation to outdoor air exchange, noise, lighting, area and flexibility in schools

Disease and well-being in relation to the intensity of the exposure to pathogenic germs, noise, area and ventilation in child-care centers

Project results

Diseases related to the indoor climate

The indoor climate in homes, day-care centers, schools and offices affects the prevalence of several types of disease, for instance infectious disease, cardiovascular disease and cancer, as well as a worsening of symptoms among persons suffering from asthma and allergy. Add to this, many Danes suffer from annoyance and general symptoms that are related to the indoor climate of buildings, including headaches, tiredness and irritated mucous membranes. Reduced well-being and comfort as a result of poor indoor climate is documented in numerous buildings. It has been demonstrated that prevalence of annoyance from noise, air quality and temperature conditions typically range between 15 and 30 per cent in offices and between 5 and 10 per cent in homes.

The prevalence of asthma and allergy has been increasing over the past decades. The prevalence in the population is about 20 per cent, and these diseases are therefore the most frequent chronic diseases among the youngest part of the adult population. There is great uncertainty about the causes of the rising prevalence, but many people consider indoor climate conditions to be a contributing factor.

Every year, 24,000 Danes die from cardiovascular diseases, and it is therefore the single most important reason for deaths in Denmark. The most significant exposures in the indoor climate which could lead to cardiovascular disease are passive smoking, particulate pollution and, perhaps, noise.

Passive smoking is believed to cause 100-430 deaths annually, while exposure to particles related to the outdoor air is believed to cause 3400 deaths, and most of these are caused by cardiovascular diseases.

Cancer can also be caused by indoor climate impacts. The three most important indoor climate exposures are: radon, tobacco smoke and other combustion products and formaldehyde. Radon is believed to cause about 250 deaths annually at simultaneous exposure to environmental tobacco smoke.

Indoor climate factors that can cause annoyance and illness

There are numerous indoor climate factors that can cause annoyance and illness:

Allergens from house dust mites, furry animals and pollen
Moulds
Bacteria and endotoxins
Particles and environmental tobacco smoke
Chemical compounds
Asbestos and radon
Odours
Noise
Temperature and draft

Building conditions

Buildings often have a durability of over one hundred years, but parts of the buildings last a shorter period and have to be changed when the need arises. Inappropriate or insufficient operation and maintenance of the building can lead to accelerating building defects and unsatisfactory indoor climate conditions.

There is a significant relation between water damage to a building and the risk of health symptoms such as wheezing, coughing and asthma. The reasons for the moisture-related health problems in the home are very complex. Part of the health problems could also be caused by the deteriorating effect of moisture on certain construction products and the fact that house dust mites and other micro-organisms thrive in moist surroundings. Water damage cannot be entirely avoided. Therefore it is important to reinforce alertness for quick alleviation of damages.

Massive moisture problems are often due to lack of or improper maintenance. Water damage in old buildings can be caused by defective or worn-down installations. Furthermore, many moisture problems in old homes can be caused by rising damp, poor insulation, incorrect post-insulating procedures and insufficient ventilation after for instance sealing tasks or change of windows. Moreover, low indoor temperatures can increase the risk of condensation on surfaces.

Airing and ventilating provide the best protection against moisture, odours, chemical compounds, particles, allergens, microorganisms, in that airing dilutes the unfortunate components. However, the ventilation system requires special attention during design and operation, if it is to work properly. Lack of cleaning of filters and poor maintenance can cause annoyance and symptoms for the occupants of the building.

Many new products are introduced based on inadequate knowledge and experience, for instance regarding their durability and service life. Different building parts have different service lives. A maintenance plan for a building can contribute to assuring the health and safety of a building.

Behavior

Through their behavior, the occupants of a building have a very great responsibility for the indoor climate quality. Old virtues, like airing by means of a draft, spring cleanings and drying clothes outdoors (or in modern tumble driers) are ever more necessary preconditions for a good indoor climate in most buildings. It is important that the occupants are aware of what means of adjustments they have in a given room. Operating staff and building designers should know that persons with direct influence on their own indoor climate are often far more content with the indoor climate quality.

Other sources

Ministry of Housing (1995). Danish Building Regulations 1995. Ministry of Housing (now the National Agency for Enterprise and Construction, Copenhagen.

ECA (European Concerted Action (1992). "Indoor Air Quality and its Impact on Man"), COST Project 613. "Guidelines for Ventilation Requirements in Buildings", Report No 11, EUR 14449 EN. Luxembourg: Office for Official Publications of the European Community.

Keiding L., Gunnarsen L., Rosdahl N., Machon M., Møller R., Valbjørn O. (2003). Environmental factors in everyday life in Denmark – with special focus on the housing environments. The National Institute of Public Health in cooperation with the Danish Building Research Institute. Copenhagen. (In Danish with an English summary.)

WHO (World Health Organization). (2000). Air Quality Guidelines for Europe, European Series, No. 91, Second Edition, World Health Organization, Regional Office for Europe, Copenhagen.