Children living in homes with mould and dampness : threat to health?

Indoor dampness induces growth of moulds, dust mites and various microbial agents. Excess moisture (together with temperature terms) may initiate the release of chemicals from building materials and furnishings. There is sufficient evidence that excessive dampness/moulds at homes is an important risk factor namely for respiratory illness. For dampness itself, the WHO has concluded that the strongest evidence exists for the association with cough, wheeze and asthma.1

There is no routinely collected data on the scope of children’s exposure to dampness/moulds at homes. Housing surveys provide the most reliable data with respect to this indicator. At present, comparable data gathered in the Eurostat SILC survey, is not available for majority of EU countries. In 2007 it should be completed for most of them. Because the comparability of data required for Health Impact Assessment (HIA) is problematic so far, a case study on HIA of exposure to damp/moulds in homes was made for Czech urban children using the assessment of doctor-diagnosed asthma cases/asthma symptoms attributable to reported damp signs/moulds. The data was available from the survey conducted on 7850 children aged 5-17 years in 2001. There was the total number of 400 360 children in the target group of the urban child population from the participant cities; this figure represents 25% of the overall number of children in the relevant age group in CZ. The doctor diagnosed asthma was recorded in 5.1 % of children, wheeze and night cough was reported in 4.5% and 15.8%, respectively. The reported recent exposure to damp spots or moulds at homes was 7.6%. The following exposure-response functions were derived from the survey: OR 1.58 (CI95 1.12 – 2.24) for asthma, OR 2.02 (CI95 1.41 – 2.89) and OR 1.38 (CI95 1.10 – 1.74) for wheeze and night cough, respectively. These findings fit in the interval found in other studies.2,3,4

The estimated share of diagnosed asthma cases consequent to the exposure of children to damp/moulds at homes amounted to 4% (range, 1% to 9%), the share of wheeze and night cough was 7% (range, 3% to 13%) and 3% (range, 1% to 5%), respectively. Extrapolating these figures to the whole Czech child population in the relevant age group, about 3100 (range, 640 to 6300) asthma cases could be attributable to dampness/moulds at homes in the Czech Republic, which means about 200 (range, 45 to 430) cases per 100 000 children in this age group. The attributable number of children with wheeze would be 4500 (range, 1910 to 7970) and the number of children suffering from night cough 570 (range, 150 to 1080). These numbers represent 330 cases (range, 130 to 550) and 140 cases (range, 40 to 270) per 100 000 children of the relevant age group, respectively.

When using surveys as a data source, there are difficulties with comparability due to various exposure definitions. The subjective element plays an important role as self-reporting is used in majority of studies. Other studies performed on indoor quality in Czech Republic showed rather greater score of moulds occurrence5, but the wording of question was different (moulds occurrence at least occasionally). As regards health outcomes, the studies have shown that asthma is often under-diagnosed for various reasons6. Therefore not only doctor diagnosed disease but also the other respiratory symptoms, such as wheeze without being cold and chronic night cough have been considered. For the future HIAs, more specific, relevant (eg. information on moulds/dampness in bedrooms) and comparable information on damp exposure in houses with children is recommended.

Go to indicator Children living in homes with problems of dampness

References:

1 Report on the WHO technical meeting on quantifying disease from inadequate housing, , Bonn, Nov 2005. http://www.euro.who.int/Housing/20060519_2

2 Bornehag CG, Blomquist G, Gyntelberg F, Järvholm B, Malmberg P, Nordvall L, Nielsen A, Pershagen G, Sundell J. Dampness in buildings and health. Nordic interdisciplinary review on the scientific evidence on associations between exposure to “dampness” in buildings and health effects (NORDDAMP). Indoor Air 2001;11:72-86

3 Bornehag C.G et al. Dampness in Buildings as a Risk Factor for Health Effects, EUROEXPO: a multidisciplinary review of the literature (1998-2000) on dampness and mite exposure in buildings and health effects. Indoor Air 2004, 14, 243-257.

4 Zacharasiewicz A; Zidek T; Haidinger G; Waldhor T; Suess G; Vutuc C: Indoor factors and their association to respiratory symptoms suggestive of asthma in Austrian children aged 6-9 years. Department of Epidemiology, University of Vienna, Austria. Wiener klinische Wochenschrift 1999, 111; (21); p882-6 ISSN: 0043-5325

5 Environmental Health Monitoring System, Summary report and Technical report, NIPH Prague, 1999, 2004, www.szu.cz

6 WHO Asthma Fact sheet, http://www.who.int/mediacentre/factsheets/fs307/en/index.html