01/08/2016 3 min

Reinforced measures for preventing mould growth in buildings and the impact of mould on human health

Today, ANSES publishes the results of its expert assessment of mould in buildings, a major issue for public health due to mould’s established effects on respiratory health, the large proportion of housing affected and the identification of population groups highly susceptible to developing pathologies when exposed. In its conclusions, the Agency recommends preventing mould in buildings first by reinforcing coordination between the sectors involved (construction, energy, etc.) and between the authorities and public entities, and second, through improved communication with housing occupants. The Agency also recommends preventing health problems, especially for the most vulnerable population groups, through changes in the regulations that would more effectively account for the risks of mould exposure in housing.

In the last several years, increasing attention has been paid to the effects of indoor environment pollution on health. ANSES was asked by the ministries of health and the environment to conduct an expert assessment on the issue of mould growth and the correlated production of mycotoxins in buildings.

The work of ANSES

The expert assessment conducted by the Agency confirms the existence of established respiratory health effects linked to mould exposure.These effects include the development or exacerbation of asthma in children, and in adults exposed in the workplace, as well as allergic rhinitis.

The assessment also showed that certain population groups are more susceptible to developing pathologies when exposed to mould.These include infants as of birth, asthmatic children and adults, individuals with a predisposition for  developing allergies (atopical subjects) or who suffer from hypersensitivity, and patients who are immunodepressed or have a chronic respiratory disease. Groups with potential overexposure to mould due to socio-economic disadvantages such as fuel poverty or overcrowded housing conditions, are also affected. 

According to the assessment, exposure to mould in indoor environments affects a high percentage of housing units, with visible mould present in 14 to 20% of French dwellings. In addition, geographical variations in fungal species also exist, mainly due to different weather and climate conditions that can have an influence at the local level.

This report, which is based on information obtained through a review of the scientific literature, consultations of various organisations in France and abroad, and hearings of practitioners in the field, was also an opportunity to take stock of the various approaches to characterising mould contamination in indoor environments. These different methods were compared and the advantages and limitations of each were specified. 

ANSES recommendations

Based on the observation that fungal risk is a major public health issue, the Agency recommends:

1 - reinforced prevention of mould proliferation in buildings, through:

  • better coordination between all those working in the sectors involved (construction, energy, etc.), as well as between the authorities and public entities, in order to improve risk management. This can be done by implementing training and information programmes to familiarise the professionals involved in housing-based activities (design, construction, renovation and remediation) with mould issues;
  • providing better information to tenants and building ownerson effective mould prevention measures in dwellings and on where to find advice to help them with these measures. For example, information campaigns on indoor air quality and activities on the territorial level could be organised.

2 - preventing health problems due to mould exposurethrough changes in housing regulations, in order to account specifically for the risks associated with this type of exposure. These changes could include:

  • regulating measures by setting mould contamination levels (ex. estimation of mouldy surface areas) with the goal being the prevention or correction of mould growth;
  • improving the collection and processing of incidents of mould growth in housing reported by residents.

These measures should be implemented preferentially for identified at-risk population groups.

The Agency encourages studies to further knowledge on the mould situation in France, its effects on health and in the human and social sciences.

What is mould?

The term "mould" refers to darkened areas which can form in dwellings (on the walls and ceilings in particular), and which are evidence of widespread proliferation of microscopic fungi. Conditions creating a favourable environment for indoor mould growth must be present, especially dampness in certain building parts (dividing walls, insulation, suspended ceilings, etc.). Mould produces spores which, when released, can remain airborne and facilitate its dispersion. Mould can also produce chemicals known as mycotoxins, which are released into the air.

The development of mould in indoor environments depends on certain technical aspects of buildings, such as ventilation, insulation and heating, which need to be taken into account as a whole. These factors are especially important when seeking to achieve greater energy efficiency in buildings. Mould can be caused by phenomena affecting a building on the structural level (for example, thermal bridges and rising damp) or ventilation systems, as well as the vulnerability of materials.