An article by Mike Halperin et al. has been published showing that SODIS is still being used by multiple families 7 years after a training project took place. In 2001, families from the communities damaged by an earthquake in Arequipa, Peru, were trained on how to use SODIS. In 2008, 42% of the interviewed families reported to be still using SODIS. When the project was completed in 2001, 75% of the families affirmed to use SODIS. This study, carried on by an independent SODIS Foundation researcher, is consistent with the 60% of sustained use reported in a study by Moser et al. and Heri. Halperin study could not confirm the existence of any specific factor fostering or preventing the sustained use of SODIS.