Efficacy of Prevention by High-Efficiency Particulate Air Filtration or Laminar Airflow Against Aspergillus Airborne Contamination During Hospital Renovation

<jats:sec id="S019594170006896X_abs1"><jats:title>Objective:</jats:title><jats:p>To evaluate efficacy of laminar airflow facilities plus high-efficiency particulate air (HEPA) filtration and HEPA filtration alone in preventing environmental<jats:italic>Aspergillus</jats:italic>contamination during hospital renovation. To show the usefulness of environmental surveillance to facilitate protection of patients at risk for invasive pulmonary aspergillosis.</jats:p></jats:sec><jats:sec id="S019594170006896X_abs2"><jats:title>Design:</jats:title><jats:p>Prospective sampling of air and surfaces for<jats:italic>Aspergillus</jats:italic>conidia during 2-year period.</jats:p></jats:sec><jats:sec id="S019594170006896X_abs3"><jats:title>Setting:</jats:title><jats:p>A hematological department adjacent to building renovation at a university hospital.</jats:p></jats:sec><jats:sec id="S019594170006896X_abs4"><jats:title>Results:</jats:title><jats:p>1,047 air samples and 1,178 surface samples were collected from January 1996 to December 1997. Significantly more air samples were positive for<jats:italic>Aspergillus</jats:italic>species during the period of building renovation than during the periods before and after renovation in a unit without a protected air supply adjacent to the building work area (51.5% vs 31.7%; odds ratio [OR], 2.3; 95% confidence interval [CI<jats:sub>95</jats:sub>, 1.4-3.7;<jats:italic>P</jats:italic><.001). A major increase in the frequency of positive air samples was also found in another adjacent unit that was protected with HEPA filtration alone (from 1.8% to 47.5%; OR, 48.9; CI<jats:sub>95</jats:sub>,12-229;<jats:italic>P</jats:italic><10<jats:sup>-7</jats:sup>). In addition, in this unit, the mean count of<jats:italic>Aspergillus</jats:italic>conidia in positive air samples increased significantly during construction (4 colony-forming units [CFU]/m<jats:sup>3</jats:sup>to 24.7 CFU/m<jats:sup>3</jats:sup>;<jats:italic>P</jats:italic>=.04) and the proportion of positive surface samples showed a significant increase during renovation (from 0.4% to 9.7%; OR, 28.3; CI<jats:sub>95</jats:sub>, 3.4-623;<jats:italic>P</jats:italic>=10<jats:sup>4</jats:sup>). However, none of 142 air samples collected during renovation in the area protected with laminar airflow plus HEPA filtration showed<jats:italic>Aspergillus</jats:italic>conidia. In a unit distant from the building renovation site, the results of air and surface samples were not affected by renovation.</jats:p></jats:sec><jats:sec id="S019594170006896X_abs5"><jats:title>Conclusion:</jats:title><jats:p>This study showed a strong association between building renovation and an increase in environmental<jats:italic>Aspergillus</jats:italic>contamination. Results confirmed the high efficacy of laminar airflow plus HEPA filtration and a high air-change rate. Although filtration with HEPA was effective during normal conditions, it alone was unable to prevent the rise of<jats:italic>Aspergillus</jats:italic>contamination related to building renovation. This study emphasized the necessity of an environmental survey of airborne contamination related to construction, to facilitate prevention of nosocomial aspergillosis outbreaks. A standardized protocol for aerobiological surveillance is needed.</jats:p></jats:sec>