Changes in surface ATP following 222-nm far-UVC irradiation: a multicentre before-and-after study in 29 healthcare facilities in Chile

Objective. To estimate surface ATP change after environmental use of 222-nm far-UVC in Chile.

Methods. Uncontrolled multicentre before-and-after study: 31 facilities considered, 29 treated, and 437 paired surface readings. A 30-minute exposure was applied at an operating distance of 2.5 m, followed by a 10-minute wait before post-cycle measurement. ATP was measured with a 3M Clean-Trace LM1. Facility-level log ratios were combined using REML, with cluster bootstrap and sensitivity analyses.

Results. Median ATP decreased from 199 to 50 RLU. The combined reduction was 81.3% (95% CI 77.7–84.3%), with I²=84.3%. All 437 post-cycle readings were below baseline. Of 174 surfaces initially ≥250 RLU, 173 reached <250 (99.4%) and 145 reached <100 (83.3%).

Conclusions. The cohort documented an ATP decrease in all analyzed surfaces, with variation between facilities. Its contribution is a multicentre estimate of change in organic or biological residues after the intervention. The before-and-after design describes this temporal association without isolating the contribution of UVC or evaluating infection reduction.