Health Risks of Dampness and Mold in Workplaces

Substantial research has been completed to investigate the associations of adverse health effects with dampness and mold in workplaces. (For information on the health consequences of dampness and mold in schools, see the section of this web site on IAQ in Schools). Sixteen studies published in 18 peer-reviewed journal articles were identified and key study features and findings are provided in Table 6. Five studies [1-5] report statistically significant increases in asthma health outcomes (asthma diagnosis, asthma exacerbation, or asthma onset) in buildings with visible dampness or mold or mold odor. A sixth study reported in three papers [6-8] found statistically significant increases in asthma outcomes in buildings with damp concrete causing an increase in airborne concentration of the chemical 2-ethyl-1-hexanol from degradation of PVC flooring placed on that concrete. Importantly, three studies [2-4] found dampness and mold associated with statistically significant increases in asthma onset (development of new asthma). The study of Jaakkola et al. [2], which has the strongest design of these three studies, reports approximately a 50% increase in onset of asthma in work places with dampness and mold. Ten out of 11 studies with health symptoms as outcomes reported a statistically significant increase in at least one type of health symptom with increased indications of dampness and mold and in many instances the prevalence of symptoms more than doubled. In most studies, some symptoms were not associated with dampness and mold. The dampness-related risk factors associated with increased health symptoms varied among these 10 studies. For three studies, symptoms increased with increased visible dampness or mold or mold odor [1, 9, 10]. In one study, increased symptoms were associated with dampness in the heating, ventilating, and air conditioning systems [11]. In one study, ultraviolet irradiation of the wet cooling coils (which reduces fungal and bacterial growth) reduced symptoms [12]. One study found symptoms increasing with higher levels of mold in chair dust but not air [13] while another study reported symptoms increasing with increased molds in floor dust but not chair dust [14]. Finally, in one study [6-8] symptoms increased in buildings with damp concrete that caused degradation of PVC flooring and increases of airborne levels of 2-ethyl-1-hexanol. One study [15] failed to find statistically significant increases in health outcomes with dampness and mold, although most health symptoms increased non-significantly and there was a statistically significant increase in workdays lost to respiratory symptoms. Most of the studies had a cross sectional design that can identify associations but not provide proof of causal relationships, although most studies controlled for a substantial set of potential confounding factors. The study of Jaakkola et al. [2] had a stronger case-control design and the study of Menzies et al. [12] was a very strong blinded crossover intervention study. In summary, the published literature indicates an association of asthma and other respiratory health outcomes in damp or moldy workplaces.

1. Cox-Ganser, J.M., et al., Respiratory morbidity in office workers in a water-damaged building. Environ Health Perspect, 2005. 113(4): p. 485-90. https://dx.doi.org/10.1289/ehp.7559.

2. Jaakkola, M.S., et al., Indoor dampness and molds and development of adult-onset asthma: a population-based incident case-control study. Environ Health Perspect, 2002. 110(5): p. 543-7.

3. Karvala, K., et al., New-onset adult asthma in relation to damp and moldy workplaces. Int Arch Occup Environ Health, 2010. 83(8): p. 855-65. https://dx.doi.org/10.1007/s00420-010-0507-5.

4. Karvala, K., et al., Prolonged exposure to damp and moldy workplaces and new-onset asthma. Int Arch Occup Environ Health, 2011. 84(7): p. 713-21. https://dx.doi.org/10.1007/s00420-011-0677-9.

5. Kim, J.L., et al., Impact of occupational exposures on exacerbation of asthma: a population-based asthma cohort study. BMC Pulm Med, 2016. 16(1): p. 148. https://dx.doi.org/10.1186/s12890-016-0306-1.

6. Norbäck, D., et al., Asthma symptoms in relation to measured building dampness in upper concrete floor construction, and 2-ethyl-1-hexanol in indoor air. Int J Tuberc Lung Dis, 2000. 4(11): p. 1016-25.

7. Nordstrom, K., et al., The effect of building dampness and type of building on eye, nose and throat symptoms in Swedish hospitals. Journal of Environmental Medicine, 1999. 1: p. 127-135. https://dx.doi.org/10.1002/1099-1301.

8. Wieslander, G., et al., Nasal and ocular symptoms, tear film stability and biomarkers in nasal lavage, in relation to building-dampness and building design in hospitals. Int Arch Occup Environ Health, 1999. 72(7): p. 451-61. https://dx.doi.org/10.1007/s004200050398.

9. Wan, G.H. and C.S. Li, Dampness and airway inflammation and systemic symptoms in office building workers. Arch Environ Health, 1999. 54(1): p. 58-63.

10. Wan, G.H. and C.S. Li, Indoor endotoxin and glucan in association with airway inflammation and systemic symptoms. Arch Environ Health, 1999. 54(3): p. 172-9.

11. Mendell, M.J., et al., Environmental risk factors and work-related lower respiratory symptoms in 80 office buildings: an exploratory analysis of NIOSH data. Am J Ind Med, 2003. 43(6): p. 630-41. https://dx.doi.org/10.1002/ajim.10211.

12. Menzies, D., et al., Effect of ultraviolet germicidal lights installed in office ventilation systems on workers' health and wellbeing: double-blind multiple crossover trial. Lancet, 2003. 362(9398): p. 1785-91. https://dx.doi.org/10.1016/S0140-6736(03)14897-0.

13. Chao, H.J., et al., The work environment and workers' health in four large office buildings. Environ Health Perspect, 2003. 111(9): p. 1242-8. https://dx.doi.org/10.1289/ehp.5697.

14. Park, J.H., et al., Fungal and endotoxin measurements in dust associated with respiratory symptoms in a water-damaged office building. Indoor Air, 2006. 16(3): p. 192-203. https://dx.doi.org/10.1111/j.1600-0668.2005.00415.x.

15. Sahakian, N., J.H. Park, and J. Cox-Ganser, Respiratory morbidity and medical visits associated with dampness and air-conditioning in offices and homes. Indoor Air, 2009. 19(1): p. 58-67. https://dx.doi.org/10.1111/j.1600-0668.2008.00561.x.

Table 6: Key features and results of research on dampness and health in workplaces other than schools.

Author Study Type	Buildings Subjects	Dampness or Mold related Risk Factors	Confounders Controlled	Key findings
Chao et al. 2003 [1] Cross sectional	98 adults in 21 offices in 4 buildings	Mold spore count in air, floor and chair dust. Principal component analysis factors based on mold.	Personal and job factors, temperature, humidity, carbon dioxide, dust load on floor and chairs	With higher chair mold levels there were statistically significant increases in upper respiratory symptoms [OR=1.35, CI = 1.07 – 1.70], and non-specific symptoms [OR = 1.87, CI = 1.11- 3.15], but not with eye symptoms. Airborne mold levels were not significantly associated with symptoms in the final models that controlled for confounding by other factors
Cox-Ganser et al. 2005 [2] Main study was cross sectional. Supplemental study compares outcome prevalence in study with reference populations	Main study- 888 adults from 1 damp building. Supplemental study- 248 adults in high respiratory symptom, vs. low respiratory symptom, vs. no respiratory symptom groups	Damp building	Smoking	Main Study: In study population of 888 adults relative to subjects of NHANES survey, there were statistically significant elevations in ever asthma [OR = 2.2, CI = 1.9 – 2.6], current asthma [OR=2.4, CI=2.0 – 3.0], adult onset asthma [OR=3.3, CI=2.7 – 4.0], wheeze [OR=2.5, CI=2.2 – 2.8], nasal symptoms [OR=1.5, CI=1.4 – 1.6], eye symptoms [OR=1.6, CI=1.4 – 1.7]. In study population relative to population in 100 representative office buildings, there were statistically significant elevations in wheeze [OR=2.9, CI=2.2 – 3.7], cough [OR=2.7, CI=2.3 – 3.2], tight chest [OR=4.7, CI=3.8 – 5.7], shortness of breath [OR=4.6, CI=3.7 – 5.7], 7-fold more adult onset asthma after starting work in building. Supplementary study: Objective tests confirmed more abnormal lung function and breathing medication use in subjects with more self-reported symptoms.
Jaakkola et al. 2002 [3] Case control	512 adults with new asthma and 912 control adults without asthma	Water damage, visible dampness, visible mold, mold odor	Sex, age, parental atopy or asthma, education level as indicator of socio economic status, smoking, environmental tobacco smoke, dampness at home, pets, occupational exposures to sensitizers, dusts, or fumes	An increased risk of new asthma (development of the disease of asthma) was associated with visible mold or mold odor at work [OR=1.54, CI=1.01 – 2.32]. There were no statistically significant associations of new asthma with water damage or damp stains without visible mold or mold odor.
Jarvis and Morey 2001 [4] Before versus after evacuation from an office building with planned mold remediation	488 occupants of mold remediated building and 122 people who had moved from this buildings to another building, reference population was 261 occupants in non-remediated office building	Before versus after evacuation from an office building with planned mold remediation	Not specified	There were statistically significant 32% to 50% decreases in throat, nose, eye, and headache symptoms after evacuation from the damp office building, but no statistically significant changes in chest tightness, shortness of breath, cough, or wheeze.
Karvala et al. 2010 [5] Cross sectional (analysis of case histories)	694 adult patients with respiratory symptoms who had been exposed to molds at work	Date of first exposure to moisture damaged workplace, level of mold exposure based on extent of mold damage and levels of airborne molds	Patients with residential moisture damage were excluded,	There was a statistically significant association of high level of mold exposure at work with development of probable work-related asthma although the odds ratio and confidence limits were not reported
Karvala et al. 2011 [6] Longitudinal	483 patients initially with asthma-like symptoms related to damp work places but without asthma, 62 of which developed asthma 3-12 years later	Continued exposure to damp or mold workplace environment, dampness remediation at work	Age, gender, atopic history, smoking habits	Continued exposure to damp or mold in workplace environment was associated with increased risk of developing asthma [OR=4.6, CI=1.8 – 11.6] The risk of developing asthma was lower and not statistically significant if there had been a dampness/mold remediation at work [OR=2.0, CI = 0.7 – 5.40] suggesting that mold remediation at work reduced the risk of developing asthma
Kim et al. 2016 [7] Cross sectional	1356 working adults who reported that they have or ever had asthma	Self-reported dampness or mold at work (visible water damage, visible mold, mold odor)	Gender, age, smoking status, second hand smoke, history of allergy	Exposure to workplace dampness or mold was associated with increased asthma exacerbation [OR=1.79, CI=1.19 – 2.67]
Mendell et al. 2003 [8] Cross sectional	2345 adults in 80 complaint office buildings in U.S.	Water in outdoor air intake, moist internal duct insulation, poor drain pan drainage, water damage in workspace.	Age, sex, smoking status, asthma status	Poor cooling coil drain pan drainage was associated with at least 3 of the following symptoms: Wheeze, shortness of breath, tight chest, cough [OR=2.6, CI=1.3 – 5.2] Poor cooling coil drain pan drainage was associated with having all three of wheeze, shortness of breath, cough [OR=2.8, CI = 1.1 – 5.2]
Menzies et al 1998 [9] Cross sectional	214 adults in 6 office buildings	Mold spore levels in air, floor dust & HVAC supply air, Indoor minus outdoor humidity	Age, sex, atopic status, smoking; temperature, humidity, carbon dioxide, total volatile organic compounds, total suspended particulates	For workers with respiratory symptoms versus those without symptoms, the probability of detectable Alternaria (a mold) in office air was significantly elevated [OR=4.2, CI=1.1 – 16.2]; For workers with symptoms, there was a significantly higher indoor air minus outdoor air humidity level (p < 0.010)
Menzies et al 2003 [10] Blinded crossover intervention study	771 adults in 3 office buildings	Ultraviolet germicidal irradiation of cooling coils as an intervention	The within-person analysis controls personal factors, temperature, humidity, carbon dioxide, nitrogen dioxide, ozone.	Operation of ultraviolet germicidal system was associated with statistically significant reductions in symptoms as follows: Any symptom [OR=0.8, CI=0.7 - 0.99]; Mucosal symptom [OR=0.7, CI=0.6 - 0.9]; Respiratory symptom [OR=0.6, CI=0.4 - 0.9] Operation of ultraviolet germicidal system was associated with a non-significant reduction in musculoskeletal symptoms [OR=0.8, CI=0.6 -1.1]
Norback et al. 2000 [11] Nordstrom et al. 1999 [12] Wieslander et al. 1999 [13] Cross sectional	87 or 88 staff (depending on analysis) from four geriatric hospitals	Dampness in concrete floor and associated elevated airborne concentrations of 2-ethyl-1-hexanol from degradation of a plasticizer in the PVC floor covering of the concrete	Age, sex, atopy, dampness at home Age, sex, tobacco smoking, atopy, psychosocial work environment, building age Age, sex, smoking habits, atopy, psychosocial index	In the two buildings with floor dampness- and elevated airborne concentrations of 2 –ethyl-1-hexanol, asthma symptoms were increased [OR 8.6, CI 1.3 – 56.7] Eye symptoms increased, not statistically significantly [OR 1.72, CI 0.89 – 3.32] Nasal symptoms increased [OR 1.13, CI 1.04 – 1.24] Throat symptoms increased [OR1.15, CI 1.05 – 1.26] General symptoms increased [OR 1.16, CI 1.07 – 1.25]* There was no association with facial skin symptoms Weekly eye symptoms in past 3 months increased [OR= 1.29, CI = 1.15 – 1.45] Weekly nose symptoms in past 3 months increased [OR= 1.10, CI = 1.02 – 1.18] There was a statistically significant decrease in tear film break up time and increase in nasal lysosome (a marker of inflammation) but no statistically significant change in nasal openness
Park et al. 2006 [14] Cross sectional	888 adults in one 20-story water damaged building	Fungi and endotoxin concentration in floor and chair dust ranked as low, medium, and high for each.	Age, gender, race, smoking, duration of occupancy.	In groups with highest versus lowest fungal concentrations in floor dust, there were statistically significant increases in lower respiratory symptoms [OR=1.7, CI=1.02-2.77 to OR=2.4, CI =1.29-4.59]; throat irritation [OR=1.7, CI=1.06-2.82]; rash/itchy skin [OR 3.0, CI=1.47-6.19]. Endotoxin increased associations of fungi on respiratory symptom, .i.e., presence of both endotoxin and fungi was associated with greater increase than their added individual effects.
Sahakian et al 2009 [15] Cross sectional	1396 office workers	Self-reported workplace dampness defined as visible mold, moldy/musty odor, or water damage; workplace air conditioning	Age, gender, smoking status, race, education, household income, geographic region, seasonal allergies, flu shot in prior year, obesity	With workplace dampness: Respiratory infections of various types increased or decreased but the changes were not statistically significant Work related nasal symptoms, lower respiratory symptoms, work related lower respiratory symptoms, constitutional symptoms, and asthma increased but the increases were not statistically significant Nasal symptoms decreased but the decrease was not statistically significant Workdays lost to respiratory symptoms increased [PR=1.30, CI=1.02 – 1.65] There were no statistically significant changes in visits to doctors
Wan et al. 1999 [16] Cross sectional	1113 adults in 9 air conditioned office buildings	Visible mold or mildew, signs of water damage, flooding.	Age, sex, atopy, job satisfaction, perceived ventilation.	Skin symptoms increased in buildings with mold [OR=2.97, CI=1.52 – 5.82], increased with water damage [OR=3.36, CI=1.70 – 6.63], and increased with flooding [OR=2.6, CI=1.19 – 2.56]. Headache increased with mold [OR=1.61, CI 1.01 – 2.56] There were non-statistically significant increases in many other symptoms including shortness of breath with mold, water damage, or flooding.
Wan et al 1999b [17] Cross sectional	109 adults in 8 office and 8 daycare buildings	Visible mold, water damage, flooding. Mold and bacteria colony forming units, & endotoxin in air. b-1,3-glucan (a marker of mold) in air .	Sex, ventilation rate, type of building	Shortness of breath, but none of nine other symptoms, was statistically significantly increased in buildings with mold [OR=20.75, CI=2.23 – 193.5] There were no statistically significant associations of water damage or flooding with symptoms of any type.
Zhang et al. 2012 [18] Longitudinal	429 adults in workplace buildings	Floor dampness, dampness or molds, moldy odor, at baseline and 10 years later	Age, sex, atopy, smoking, education level	There were no statistically significant associations of dampness and mold at baseline with subsequent new sick building syndrome symptoms. Floor dampness in the final year was associated with onset of mucosal symptoms [OR=4.46, CI = 1.39 – 14.35]. Floor dampness at any workplace during the 10 year period was associated with onset of mucosal symptoms [OR= 2.43, CI= 1.05 – 5.64] There were non-statistically significant increases in onset of general and mucosal symptoms with other indicators of dampness and mold. There were decreased remissions of symptoms present at baseline in buildings with dampness and mold indicators, but only one decrease in remission was statistically significant with decreased remission of general symptoms in buildings repaired because of dampness [OR = 0.21, CI = 0.07 – 0.70]. There was evidence, sometimes statistically significant, that dampness and mold was associated with increased biomarkers of inflammation and increased bronchial responsiveness

Key to table: CI = 95% confidence interval; OR = odds ratio; PR = prevalence ratio *In this study, general symptoms were not defined but the term usually refers to headache, fatigue, dizziness, difficulty concentrating.

1. Chao, H.J., et al., The work environment and workers' health in four large office buildings. Environ Health Perspect, 2003. 111(9): p. 1242-8. https://dx.doi.org/10.1289/ehp.5697.

2. Cox-Ganser, J.M., et al., Respiratory morbidity in office workers in a water-damaged building. Environ Health Perspect, 2005. 113(4): p. 485-90. https://dx.doi.org/10.1289/ehp.7559.

3. Jaakkola, M.S., et al., Indoor dampness and molds and development of adult-onset asthma: a population-based incident case-control study. Environ Health Perspect, 2002. 110(5): p. 543-7.

4. Jarvis, J.Q. and P.R. Morey, Allergic respiratory disease and fungal remediation in a building in a subtropical climate. Applied Occupational and Environmental Hygiene, 2001. 16(3): p. 380-388. https://dx.doi.org/10.1080/10473220117482.

5. Karvala, K., et al., New-onset adult asthma in relation to damp and moldy workplaces. Int Arch Occup Environ Health, 2010. 83(8): p. 855-65. https://dx.doi.org/10.1007/s00420-010-0507-5.

6. Karvala, K., et al., Prolonged exposure to damp and moldy workplaces and new-onset asthma. Int Arch Occup Environ Health, 2011. 84(7): p. 713-21. https://dx.doi.org/10.1007/s00420-011-0677-9.

7. Kim, J.L., et al., Impact of occupational exposures on exacerbation of asthma: a population-based asthma cohort study. BMC Pulm Med, 2016. 16(1): p. 148. https://dx.doi.org/10.1186/s12890-016-0306-1.

8. Mendell, M.J., et al., Environmental risk factors and work-related lower respiratory symptoms in 80 office buildings: an exploratory analysis of NIOSH data. Am J Ind Med, 2003. 43(6): p. 630-41. https://dx.doi.org/10.1002/ajim.10211.

9. Menzies, D., et al., Aeroallergens and work-related respiratory symptoms among office workers. J Allergy Clin Immunol, 1998. 101(1 Pt 1): p. 38-44. https://dx.doi.org/10.1016/S0091-6749(98)70191-5.

10. Menzies, D., et al., Effect of ultraviolet germicidal lights installed in office ventilation systems on workers' health and wellbeing: double-blind multiple crossover trial. Lancet, 2003. 362(9398): p. 1785-91. https://dx.doi.org/10.1016/S0140-6736(03)14897-0.

11. Norbäck, D., et al., Asthma symptoms in relation to measured building dampness in upper concrete floor construction, and 2-ethyl-1-hexanol in indoor air. Int J Tuberc Lung Dis, 2000. 4(11): p. 1016-25.

12. Nordstrom, K., et al., The effect of building dampness and type of building on eye, nose and throat symptoms in Swedish hospitals. Journal of Environmental Medicine, 1999. 1: p. 127-135. https://dx.doi.org/10.1002/1099-1301.