House characteristics and condition as determinants of visible mold and musty odor: Results from three New Zealand House Condition Surveys in 2005, 2010, and 2015

Abstract

Consistent associations between indoor damp and respiratory symptoms have been demonstrated, 1,2 with indoor mold suggested to play a key role, 3 although the specific underlying mechanisms remain largely unclear. 4 In addition to visible mold, the presence of musty and moldy odor has also been associated with respiratory symptoms and rhinitis. [5][6][7] These dampness-related health effects present a major and avoidable cost to individuals' health and to the healthcare system, as demonstrated both in New Zealand 8 and internationally. 9Evidence suggests that even small improvements in housing quality may have significant health benefits, 10-12 but due to the complexity of the causes of indoor dampness, which are multi-factorial and frequently inter-related, it is unclear which specific improvements are most effective. Better understanding of the relative importance of the many contributing factors of indoor dampness is therefore

Associations of house characteristics with indoor dampness and measured moisture: Results from three New Zealand House Condition Surveys in 2005, 2010 and 2015

“…This may be the due to warm indoor air creating a "stack effect", resulting in damp air from the subfloor space to be drawn upwards, thus infiltrating into the interior [51]. In contrast to our current findings, a previous study conducted by this research team, using data from the same three surveys, showed no association between subfloor defects and visible mould [24]. The reason for this difference may be that subjective dampness and damp subfloor conditions are more closely associated with climatic conditions at the time of the survey than the presence of visible mould, which is more likely to be related to conditions over a longer time period.…”

“…Building envelope condition defects were generally associated with increased indoor dampness, with a significant dose-response pattern observed for the aggregated variable in all three surveys. Consistent with this, and using data from the same three surveys, we have previously shown a similar association between BEC and both indoor visible mould and musty odour (both inspector-assessed) [24]. A study from Quebec that assessed self-reported dampness in 2097 student dormitory rooms also found a dose-response association between poor repairs and increased dampness [16], whilst two other studies found increased mould in houses with poor repairs [23,41].…”

“…House and household characteristics have been associated with subjective dampness indicators in several studies, including higher occupancy [11][12][13][14], tenancy vs home ownership [15][16][17], no or poor insulation [18,19], lack of (mechanical) ventilation [15,16,20], older houses [11,16,[20][21][22], and poor repairs and maintenance [16,23,24]. Some of these characteristics have also been associated with higher indoor relative humidity or other objective measures of dampness, including higher occupancy [25,27,28], lack of insulation [19,27], lack of efficient and effective heating [25,26,27,29] and less ventilation [30].…”

“…We have previously reported associations between house characteristics and visible mould and musty odour using data from three iterations of the New Zealand House Condition Survey, conducted in 2005 (n = 565), 2010 (n = 491) and 2015 (n = 560) [24]. These three surveys collected detailed data on the physical characteristics of these houses as well as some household characteristics, and showed that poorer ventilation, insulation and condition of the building envelope were independently associated with increased visible mould and musty odour (both inspector assessed), after adjustment for climate and other household characteristics including tenure and number of occupants [24].…”

“…We have previously reported associations between house characteristics and visible mould and musty odour using data from three iterations of the New Zealand House Condition Survey, conducted in 2005 (n = 565), 2010 (n = 491) and 2015 (n = 560) [24]. These three surveys collected detailed data on the physical characteristics of these houses as well as some household characteristics, and showed that poorer ventilation, insulation and condition of the building envelope were independently associated with increased visible mould and musty odour (both inspector assessed), after adjustment for climate and other household characteristics including tenure and number of occupants [24]. The aims of the current study were to assess associations with outcomes of inspector-rated subjective (feeling of) indoor dampness and moisture measurements (moisture content) taken from ceiling and floor joist timbers using data from the same three surveys, with the overall goal of improving understanding of the determinants of indoor dampness, thus contributing to improved interventions to reduce indoor dampness.…”