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Indoor Air Quality

1. Introduction – assessing health risks of indoor air pollution

    The SCHER opinion states:


    Air quality is one of the major environmental health concerns for Europe. The main goal of the Community policy on air pollution is to achieve levels of air quality that do not result in unacceptable risks to human health.

    Until now, much progress has been made in Europe in tackling outdoor air pollutants with Community legislation on emission sources available since 1970 and on air quality standards since 1980. This legislation has been continuously updated. The most recent EU quality standards are defined within the Air quality framework directive from 19961 and subsequent directives2. The air quality directives require Member States to set up and maintain a system for assessing outdoor air quality and to draw up action plans to reach the objectives of the EC directives. Limit values have been adopted for outdoor air concentration of the most common pollutants such as sulphur dioxide, lead and particulate matter3. In 2001, the Commission also launched an air quality programme Clean Air for Europe (CAFÉ)4 to prepare a long term strategy on air pollution, which was adopted by the Commission on 21 September 2005.

    In 2002, four priority areas to be tackled with urgent actions were identified in the EU’s Sixth Community Environment Action Programme5. One of the priority areas is the Environment and health and quality of life. In 2003, the European Commission adopted a new Strategy on Environment and Health6 with the overall aim to reduce diseases caused by environmental factors in Europe. Among others, air quality is one of the main identified problems of environmental pollution related to health problems such as respiratory diseases, asthma and allergies.

    This strategy was followed by the EU Action Plan on Environmental and Health7. In this plan, the “action 12” intends to develop work on improving indoor air quality.

    These initiatives recognize the importance of a complete integrated strategy on air pollution which considers not only the outdoor air but also includes possible solutions concerning indoor air pollutants. As reported in the communication on a European Environment and Health Strategy, a broad stakeholder involvement is also foreseen which includes a consultative group on “Environment and Health”. The Commission will use this group to consult on analyses of environment and health data, and risk management measures. The analyses in question will rely in part on the work of the SCHER to identify missing links in existing monitoring systems.

    Indoor exposures to air pollutants may occur in both private and public indoor environments such as homes, offices, schools, and transport systems.

    Most indoor air pollutants consist of chemicals released, for example, the use of cleaning products, air fresheners, pesticides and emissions from furniture and construction materials, heating and cooking. In addition, outdoor sources may contribute to indoor air pollution. Aspects such as thermal insulation and ventilation rates may also play a role. Microbiological contaminants which may induce allergies and asthma also require consideration as indoor air pollutants. Examples of potential serious effects include respiratory disorders, including asthma and cancer.

    1 OJ L296/55 21 November 1996
    2 OJ L163/41, 29 June 1999, OJ L313/12, 13 December 2000, OJ L67/14 9 March 2002, L23/3 26 January 2005
    3 OJ L163/41 29 June 1999
    4 COM (2001) 245 final
    5 OJ L 242 10/9/2002
    6 COM (2003) 338 final
    7 COM (2004) 416 final

    Source & ©: SCHER,  Opinion on risk assessment on indoor air quality (2007),
    3. Background, p. 5-6

    3. OPINION

    Indoor air constitutes a complex case for risk assessment and management due to a wide variety of pollutants, exposure levels, different possible health outcomes, differences in sensitivity of the population, cultural habits, way of living, building stock and climate across Europe.

    Global trends such as climate change and rise of energy costs may have important effects on indoor air quality through for example, extreme weather conditions and need to additional thermal insulation and decreased ventilation. These may lead to too high or too low indoor temperatures or to dampness problems.

    Possible health risks of indoor air pollution and aspects of risk assessment have been addressed recently in European and international working groups and projects (WHO 1997, ECA 2000, INDEX 2005, California EPA 2005).

    The opinion is aimed to cover indoor environments where the general public may be exposed to pollutants, such as private homes and public buildings e.g., schools, day care centres, offices and places of leisure. Transport vehicles (vehicle compartments) are specific indoor environments. The same risk assessment principles can be applied for them but the means of risk management may differ. Industrial exposures, including professional cleaning, in indoor environments are excluded because they do not represent the exposure of the general public; and specific exposure limits for contaminants are established. In addition, the opinion does not cover active smoking but environmental tobacco smoke (ETS) is included.

    The SCHER emphasises that the opinion covers only risk assessment principles which are recommended to be applied in indoor environments and does not cover risk management, the practical means to decrease/prevent adverse health effects.

    The opinion draft was on public comments through the internet and was finalized after consideration of the comments received.

    3.1. Question 1

    To provide a basis for assessment of risks to human health from indoor air quality, and a sound scientific basis for the development and implementation of policies, the SCHER is asked to identify a Risk Assessment Strategy to support policy on indoor air quality. The Committee is particularly asked to take into account potentially vulnerable groups of population such as children, pregnant women and elderly. The committee is also asked to consider the practicality of a risk assessment which takes into account on combined exposure and cumulative effects of specific air pollutants.

    Answer to Question 1

    3.1.1. Risk Assessment for indoor air

    The SCHER recommends to use the basic paradigm for toxicological risk assessment, (Commission Directive 93/67/EEC; Council Regulation (EEC) 793/93; TGD, 2003) in support of the indoor air quality policy. It takes into account all necessary elements in health risk assessment: the hazards, their dose-response, exposure and results in science-based risk characterisation (Commission Regulation (EC) No. 1488/94; Technical Guidance Document on Risk Assessment). Where possible, the margin of safety/exposure should be defined or the exposure should be compared with relevant health based guideline values for risk characterisation. In the case this is not possible a scientific based hazard characterisation should be attempted.

    Where diseases, risk of diseases, symptoms or complaints are obviously related to unacceptable indoor conditions (e.g. serious over crowdedness, extreme heat, lack of ventilation, excessive dirtiness, excessive microbial growth and dampness) and combustion products, no further detailed risk assessment may be needed and risk management may directly be performed.

    Source & ©: SCHER,  Opinion on risk assessment on indoor air quality (2007),
    3. OPINION, p. 6-7

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