Abstract

Microbial pollution is a key element of indoor air pollution. It is caused by hundreds of species of bacteria and fungi, in particular filamentous fungi (mould), growing indoors when sufficient moisture is available. This document provides a comprehensive review of the scientific evidence on health problems associated with building moisture and biological agents. The review concludes that the most important effects are increased prevalences of respiratory symptoms, allergies and asthma as well as perturbation of the immunological system. The document also summarizes the available information on the conditions that determine the presence of mould and measures to control their growth indoors. WHO guidelines for protecting public health are formulated on the basis of the review. The most important means for avoiding adverse health effects is the prevention (or minimization) of persistent dampness and microbial growth on interior surfaces and in building structures.

Contents

• Contributors
• Acknowledgements
• Foreword
• Executive summary
• 1. Introduction
  • 1.1 Background
  • 1.2 Scope of the review
  • 1.3 Preparation of the guidelines
  • 1.4 Guidelines and indoor air quality management
• 2. Building dampness and its effect on indoor exposure to biological and non-biological pollutants
  Jeroen Douwes.
  • 2.1 Frequency of indoor dampness
  • 2.2 Effects of dampness on the quality of the indoor environment
  • 2.3 Dampness-related indoor pollutants
  • 2.4 Exposure assessment
  • 2.5 Summary and conclusions
• 3. Moisture control and ventilation
  Olli Seppänen and Jarek Kurnitski.
  • 3.1 Introduction
  • 3.2 Sources of moisture
  • 3.3 Mould and mites as indicators of building performance
  • 3.4 Ventilation performance
  • 3.5 Ventilation systems
  • 3.6 Outdoor and other sources of pollution related to ventilation
  • 3.7 Ventilation and spread of contaminants
  • 3.8 Moisture control in buildings
  • 3.9 Measures to protect against damage due to moisture
  • 3.10 Conclusions and recommendations
• 4. Health effects associated with dampness and mould
  Mark J Mendell, Anna G Mirer, Kerry Cheung, Jeroen Douwes, Torben Sigsgaard, Jakob Bønløkke, Harald W Meyer, Maija-Riitta Hirvonen, and Marjut Roponen.
  • 4.1 Review of epidemiological evidence
  • 4.2 Clinical aspects of health effects
  • 4.3 Toxicological mechanisms
  • 4.4 Synthesis of available evidence on health effects
• 5. Evaluation of human health risks and guidelines
  • 5.1 Summary
  • 5.2 Conditions that contribute to health risks
  • 5.3 Guidelines
• 6 References
• Annex 1 Summary of epidemiological studies
• Annex 2 Summary of in vitro and in vivo studies

The designations employed and the presentation of the material in this publication do not imply the expression of any opinion whatsoever on the part of the World Health Organization concerning the legal status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries. Where the designation ‘country or area’ appears in the headings of tables, it covers countries, territories, cities and areas. Dotted lines on maps represent approximate border lines for which there may not yet be full agreement.

The mention of specific companies or of certain manufacturers’ products does not imply that they are endorsed or recommended by the World Health Organization in preference to others of a similar nature that are not mentioned. Errors and omissions excepted, the names of proprietary products are distinguished by initial capital letters.

The World Health Organization does not warrant that the information contained in this publication is complete or correct and shall not be liable for any damages incurred as a result of its use. The views expressed by authors or editors do not necessarily represent the decisions or the stated policy of the World Health Organization.