Airborne Legionella bacteria from pulp waste treatment plant: aerosol particles characterized as aggregates and their potential hazard

• Published in: Aerobiologia Vol. 27; no. 2; pp. 147 - 162
• Main Authors: Blatny, Janet Martha, Ho, Jim, Skogan, Gunnar, Fykse, Else Marie, Aarskaug, Tone, Waagen, Viggo
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01.06.2011
• Subjects: Aerosol particles; Aerosols; Allergology; Alveoli; Atmospheric Protection/Air Quality Control/Air Pollution; Earth and Environmental Science; Electrophoresis; Environment; Environmental Engineering/Biotechnology; Environmental Health; Legionella; Lethal dose; Original Paper; Plant diseases; Plant Pathology; Pneumology/Respiratory System; Pulp; rRNA 16S; Samplers; Waste treatment; Waste treatment facility; Aggregates; Aerosol particles; Environmental hazard
• ISSN: 0393-5965; 1573-3025
• DOI: 10.1007/s10453-010-9184-9

In response to reported outbreaks of Legionnaires’ disease near a biological waste treatment plant, Legionella -containing aerosols were characterized at this location. Culturable bacteria-containing particles were assessed with slit-to-agar samplers and liquid impingement. Results showed that the air at this location contained a higher level of airborne Legionella particles compared to that of a control clean location 90 km away. On average, about 1 of 50 culturable particles contained Legionella (2%). The median particle size was estimated to 3.5 μm permitting an estimation of a maximum about 147 Legionella cells per aggregate. This implies that in <11 h, a human under such conditions (worse-case), may inhale an estimated lethal dose of individual Legionella cells (1,000 cells, 100% alveolar retained deposition level). Additionally, 44 taxonomically different airborne bacterial genera were measured at the treatment plant using denaturing gradient-gel electrophoresis (DGGE) and 16S rDNA analysis of air samples. Of these, 64% of the genera were not detected at the clean location. Our findings suggest that the treatment facility may emit respirable particles, as complex aggregates, containing a mixture of several Legionella cells and other bacterial cells. These findings can potentially have an impact on assessing environmental risk exposure and health hazard prediction modeling.