Application of the NIOSH Dampness and Mold Assessment Tool (DMAT) and Interpretation of Its Scores to Protect Building Occupants’ Health

1723 

Professional Poster 

J Park¹

¹CDC/NIOSH, Morgantown, WV

Dr. Ju-Hyeong Park, ScD, MPH, CIH. FAIHA  
CDC/NIOSH

This presentation provides an overview of the National Institute for Occupational Safety and Health (NIOSH) Dampness and Mold Assessment Tool (DMAT) for evaluating building dampness and mold (D/M), including how to calculate and interpret DMAT scores to inform building management decisions on D/M surveillance, health surveillance, and repair/remediation. It also summarizes findings from an epidemiologic study of 50 elementary schools and discusses an estimated DMAT action score to help reduce D/M-associated adverse health effects.

"Indoor D/M remains a prevalent and persistent environmental condition in buildings and has been consistently associated with adverse health outcomes among occupants [Mendell et al., 2011]. To facilitate standardized evaluation and management of D/M-and to support remediation planning and health-protection considerations-NIOSH developed and published the Dampness and Mold Assessment Tool (DMAT) in 2019 [NIOSH, 2019]. DMAT is a structured observational instrument applicable across building types that generates continuous, quantitative D/M scores through systematic room- and area-level assessments based on visual inspection and olfactory (odor) evaluation.

Despite the availability of DMAT, information remains limited on how DMAT scores correspond to occupant health risk and how to interpret them to inform remediation and health-protection decisions. This presentation will quantify health risks among adult school building occupants using composite DMAT-derived D/M scores and will discuss how to interpret these scores to inform building management, health or D/M surveillance, and remediation decisions."

"Using the DMAT, we evaluated four D/M-related factors-water damage, visible mold, and damp or wet materials-across eight room components: ceiling, walls, windows, floor, pipes, furniture, HVAC (heating, ventilation, and air conditioning), and materials. Mold odor was assessed at the room level. Scores were assigned based on the size or intensity of observed damage and dampness, and on the intensity of mold odor. For each room, we calculated a total DMAT score by summing scores across assessed components and factors. Floor-level average scores were then calculated from these room total scores.

From 2015 to 2016, we conducted a cross-sectional epidemiologic study in 50 public elementary schools in a large city in the northeastern United States. During summer 2015, D/M was assessed in all 6,492 accessible rooms and areas. Concurrently, health data were collected via a web-based questionnaire from 1,529 workers in the 50 schools, including self-reported physician-diagnosed lifetime and current asthma, post-hire onset asthma, and upper and lower respiratory and non-respiratory symptoms during the prior 12 months and their building relatedness (defined as improvement when away from work). For analysis, participants were assigned the floor-level average DMAT score as their exposure based on their reported floor within the school. Multivariable logistic regression models were used with DMAT scores as the primary exposure variable and were adjusted for age, sex, race, ethnicity, teaching status, self-reported mold odor at home in the prior 12 months, and school-level poverty rate. Prevalence ratios (PRs) and 90% confidence intervals (CIs) were then estimated using the delta method and conditional standardization. Linearity of exposure–response relationships was evaluated using generalized additive models and likelihood-ratio tests. The study was reviewed and approved by the NIOSH Institutional Review Board, and all participants provided informed consent."

"We found that each 1-unit increase in DMAT score was associated with a 7–12% linear increase in the prevalence of asthma and respiratory symptoms (wheeze, shortness of breath, cough, stuffy/itchy nose) and a 6–16% linear increase in the prevalence of systemic symptoms (difficulty remembering, confusion, dizziness/lightheadedness, headache). Associations were generally stronger for building-related asthma and building-related respiratory and systemic symptoms than for non–building-related symptoms, and we found little evidence of overall nonlinearity in DMAT score–health relationships.

Because we lacked external data on asthma or respiratory symptom prevalence in non-problem (dry) schools to anchor an action threshold, we relied on internal study distributions. Using the observed linear exposure–response for asthma and the study's internal tertile data-average floor-level DMAT score in the highest tertile (4.96), asthma prevalence in the highest tertile (18.3%) in relatively damp schools, asthma prevalence in the lowest tertile (14.3%) as a proxy for background prevalence in relatively dry schools, and the estimated PR (1.08)-we estimated a potential DMAT action score of 2.0. This suggests that room total scores or floor/school average scores ≥2.0 may warrant more frequent D/M surveillance and heightened awareness of potential related health impacts among occupants. Regardless of score, moderate or strong mold odor warrants investigation for hidden mold, and any identified sources of water intrusion or hidden mold growth require remediation; visible mold also warrants attention even when the DMAT score is below 2.0, as it likely reflects ongoing moisture problems. A key limitation of the study is the absence of comparison schools with health outcome data, which would strengthen estimation of an action score. Future epidemiologic studies applying DMAT and collecting health outcomes in both problem and non-problem buildings will be essential to validate and refine this proposed action level."

Indoor Air Quality

Exposure Assessment