# Hygiene heroes: a cluster-randomized trial of a hygiene curriculum in Tamil Nadu schools

## TL;DR

A school-based hygiene curriculum in India significantly improved handwashing practices among students in low-resource settings.

## Contribution

The study demonstrates a scalable hygiene curriculum's effectiveness in promoting handwashing in low-resource schools.

## Key findings

- Handwashing with soap before lunch doubled in treated schools after the intervention.
- Treated schools showed roughly 30 percentage point improvement in hygiene outcomes compared to control schools.
- The intervention used existing school staff, suggesting scalability in low-resource settings.

## Abstract

Respiratory infections and diarrheal diseases are major causes of illness and school absences for school-aged children. Both can be prevented by handwashing with soap. Unfortunately, at most schools in low-resource settings, soap and water are rarely present and, if present, rarely used. As part of a longer-term project, we have been working with the Tamil Nadu school system on improving the hygiene practices of students since 2015. We have designed a handwashing curriculum to educate students at low-resource schools in India to promote behavior change among these students and their teachers. The purpose of this study is to measure how effective this curriculum is in improving handwashing outcomes.

From October 2019 through March 2020, we ran a cluster-randomized trial of a school-based hand hygiene intervention for students in grades 3 to 5 in Tamil Nadu public schools. Schools in the treated group implemented a handwashing curriculum to educate students about the importance of handwashing and to create routines within the school. During baseline, midline and endline, enumerators conducted surprise visits at schools to observe whether soap was present in classrooms and whether students were washing their hands with soap before lunch. The intervention occurred at treatment schools between baseline and midline.

The observed presence of in-use soap and handwashing before lunch more than doubled at treated schools after the intervention. Both outcomes were also roughly 30 percentage points higher at treated schools than at control schools at midline, providing some indication that a hygiene intervention can succeed in a low-resource setting.

Our results indicate that the intervention was successful at improving handwashing with soap. Since the intervention used the school system’s own trainers and teachers, it should be scalable. As such, a hygiene intervention like the one we implemented can succeed in a low-resource setting. Longer-term follow-up is important to see what reminders help schools and students sustain the new behavior.

AEARCTR-0005182 (AEA RCT Registry, Initial Registration Date was December 15, 2019).

The online version contains supplementary material available at 10.1186/s12889-025-25349-6.