Aerosol exposure assessment during reclaimed water utilization in China and risk evaluation in case of Legionella

Reclaimed water utilization provides an effective way to alleviate water shortage. However, the residual pathogens in the recycled water like Legionella, could be spread into the air as aerosols through water-to-air transmission process. Inhaling the aerosols by the people nearby increases their susceptibility to diseases. For estimating the health risks associated with the potential exposure of airborne Legionella emitted from the urban use of reclaimed water in China, nationwide questionnaire was designed to investigate the exposure habits of Chinese population in different scenarios. Quantitative microbial risk assessment (QMRA) served as the suitable explanatory tool to estimate the risk. The results indicated that annual infection probability of populations exposed to Legionella for three scenarios, 0.0764 (95% CI: 0.0032-0.6880) for road cleaning, 1.0000 (95% CI: 0.1883-1.0000) for greenfield irrigation, 0.9981 (95% CI: 0.0784-1.0000) for landscape fountain, were markedly higher than the threshold recommended by WHO (10(-4) per person per year (pppy)) according to the concentration distribution of Legionella in the reclaimed water. An age-, educational background-, region- and gender-specific data in annual infection probability also showed different tendencies for some subpopulations. This study provides some detailed information on the health risks from the water reuse in China and will be useful to promote the safe application of reclaimed water in water-deficient areas. (C) Higher Education Press 2021

Automated summary

Reclaimed water utilization is an effective method to alleviate water shortage, but it carries the risk of spreading pathogens like Legionella through water-to-air transmission, increasing the susceptibility of people to diseases. A nationwide questionnaire in China investigated the exposure habits of the population in different scenarios, and quantitative microbial risk assessment (QMRA) was used to estimate the risk. The results showed that the annual infection probability of Legionella exceeded the recommended threshold by WHO, indicating the potential health risks associated with the reuse of reclaimed water.