Condition category
Date applied
Date assigned
Last edited
Prospectively registered
Overall trial status
Recruitment status
Not yet recruiting

Plain English Summary

Background and study aims
Breathing in other people's smoke is called second-hand smoking (SHS). SHS is harmful to children's health and leads to chest and ear infections, tuberculosis, meningitis and asthma. It also causes lung cancer and heart disease. Globally, 40% of children are exposed to SHS. Many countries have introduced bans on smoking in enclosed public spaces, but for the majority of children, cars and homes remain the most likely places for them to breathe in SHS. The only possible way to protect children from SHS is to make cars and homes completely smoke-free. The researchers have conducted a pilot study involving children, teachers and parents in schools in Bangladesh to develop and test a school-based intervention called ‘Smoke-Free Intervention’ (SFI). Their work has shown promising results showing that SFI can encourage children to negotiate smoking restrictions inside their homes. They have also conducted a feasibility study in Pakistan where SFI was culturally adapted and was found acceptable to be delivered in school. The aim of this study is to examine how effective SFI is at preventing respiratory and other smoking-related illnesses in Bangladesh and Pakistan by reducing children's exposure to SHS. Pakistan is included because of its comparable disease burden to Bangladesh.

Who can participate?
Children studying in year 5 (9 to 12 years old) at participating schools

What does the study involve?
The researchers are proposing to conduct this study in Dhaka, Bangladesh and Karachi, Pakistan. They will recruit a total of 68 primary schools, 34 from each site. They will conduct measurements including testing children's saliva for cotinine, a chemical detected in those exposed to SHS. Other measures will include questionnaires and diaries to be kept by children to record their chest symptoms and scales to measure school performance and attitudes to smoking. Once measurements have been taken, half of the schools will be randomly chosen to receive SFI while the other half will not receive the intervention until the end. The Smoke-Free Intervention (SFI) comprises six interactive lessons delivered by school teachers including five fun activities and one take-home educational resources. Taught lessons increase pupils' knowledge about the associated harms of SHS. Fun activities including storytelling, role-playing, quizzes and games, motivate children to act and feel confident in persuading adults to take seven steps away from the house to smoke. The take-home resource also helps children to negotiate with their families to "sign-up" to a voluntary contract to make their homes smoke-free. The researchers will repeat the assessments at 3, 6 and 12 months after the intervention.

What are the possible benefits and risks of participating?
Some of the concerns are as follows. Children’s participation raises issues around competence, vulnerability and powerlessness. In this study, children’s wishes and their welfare will take precedence over the research requirements. Research burden will be kept to a minimum. Children and their families will not be reimbursed financially, however, small incentives in the form of school stationery will be offered. Based on the feasibility work, it is highly unlikely that the children will face any adverse reaction from their families. Obtaining saliva is also not harmful to children, neither it could disclose the presence of any medical condition. All participants’ data will be kept confidential and in password-protected servers. The risks associated with this study are minimal, and it is unlikely that the questionnaires or interviews will lead to any potential legal, social, or psychological problems. The process of collecting saliva samples is also easy and safe. Each participant will place a cotton dental roll inside the cheek for 2 minutes to collect saliva. Soaked cotton rolls will be placed in a plastic container. Study personnel will provide detailed instructions to the participants for the saliva sample. The participant will be entitled to withdraw at any time of the research process even after s/he initially agreed to participate.

Where is the study run from?
The study will be centrally coordinated from The University of York (UK). In each country it will be run from Aga Khan University (Pakistan) and the ARK Foundation (Bangladesh).

When is the study starting and how long is it expected to run for?
December 2019 to July 2023

Who is funding the study?
1. Medical Research Council (MRC) (UK)
2. Wellcome Trust (UK)
3. National Institute of Health Research (NIHR) (UK)

Who is the main contact?
Prof. Kamran Siddiqi

Trial website

Contact information



Primary contact

Prof Kamran Siddiqi


Contact details

Department of Health Sciences
Seebohm Rowntree Building
The University of York
YO10 5DD
United Kingdom
+44 (0)7970 544872



Additional contact

Prof Kamran Siddiqi


Contact details

Department of Health Sciences
Seebohm Rowntree Building
The University of York
YO10 5DD
United Kingdom
+44 (0)7970 544872

Additional identifiers

EudraCT number

Nil known number

Nil known

Protocol/serial number

Version 1.3, 20th February 2020

Study information

Scientific title

Children Learning About Second-hand Smoking (CLASS III): a cluster randomised controlled trial



Study hypothesis

The aim of this study is to examine how effective SFI is at preventing respiratory and other smoking-related illnesses in Bangladesh and Pakistan by reducing children's exposure to SHS.

Ethics approval

Approved 16/04/2020, Health Sciences Research Governance Committee (HSRGC) at The University of York (Department Of Health Sciences, York, YO10 5DD, UK; +44 (0)1904 323253;, no ref number

Study design

Multi-centre cluster randomised controlled trial

Primary study design


Secondary study design

Cluster randomised trial

Trial setting


Trial type


Patient information sheet

Not available in web format, please use contact details to request a participant information sheet


Prevention of respiratory illnesses in children


1. Smoke Free Intervention (SFI):
The proposed trial (CLASS III) is the natural sequence, which follows the encouraging findings of the above studies and uses the MRC Framework for Developing and Evaluating Complex Interventions.
All participating children in the intervention arm will receive the SFI delivered by their teachers. Teachers will receive prior training in delivering the intervention. Their training will focus on their knowledge gaps around tobacco, their skills in using various teaching methods and their ability to build confidence within and teach negotiation skills to children.
The intervention will consist of:
Two 45-minute sessions delivered over two days by schoolteachers. The duration of these sessions is consistent with regular school lessons. These sessions will consist of a flip chart presentation and a full drama activity. These activities are especially designed to increase pupil’s knowledge about SHS and related harms, and motivate them to follow one main step (7 steps away from home) to make their home smoke free. The seven acts of the drama will give children the opportunity to practice their negotiating skills and be confident within their cultural context.It will also serve as a visual incentive for the parents not to smoke inside homes.
A set of four follow-up sessions (15 minutes each) to reinforce key messages delivered in the initial sessions, to be delivered once a week over 6-7 weeks after the two initial sessions. The immediate first follow up session will be based on the feedback from parents about the drama activity. The second session will consist of a word search game followed by a discussion in order to enhance pupils’ knowledge about SHS. The third follow up session will comprise a quiz game in which children will be asked questions and given answer options. This will be followed by a discussion as a means of reinforcement. The final follow up session will be based on small group discussions among the students about their experiences and if they faced any challenges.
Children are given an achievement certificate to mark the seven achievements to make their homes smoke free. Children are also given a promise form that describes the main step to achieve a smoke-free home i.e to take seven steps away from the house to smoke. It also contains a tear-off slip to make a commitment to impose smoking restrictions at home. Children take promise forms to their parents, show them the messages, and negotiate with them to “sign-up” to the Smoke-Free Homes “promise” form. One of the implications is that even if parents are non-smokers, they will not allow other smokers (residents and visitors) to smoke inside homes. In addition to delivering the intervention, teachers will also be trained to support children in this process.

2. Treatment as usual:
Schools in the control arm will receive the intervention at the completion of the trial.

Intervention type



Drug names

Primary outcome measure

Exposure to second-hand smoking measured by checking salivary cotinine level at baseline and month 3

Secondary outcome measures

1. Frequency and severity of respiratory symptoms recorded by asking children to keep a diary for 13 respiratory symptoms and record their severity on a validated four-point Likert scale for a whole month (4 weeks) in three follow up periods i.e. 3rd, 6th and 12th month. For each item, ‘0’ represents the absence of a symptom, 1 represents mild, 2 represents moderate and 3 represents the greatest severity level
2. Smoking-related behaviour recorded by asking the children to self-report levels of smoking restrictions and social visibility of smoking at home through a questionnaire at baseline, and months 3, 6 and 12
3. Health service use recorded by using a health service utilisation questionnaire at baseline, and months 3, 6 and 12
4. Quality of life assessed using the CHU-9D questionnaire at baseline, and months 3, 6 and 12
5. Absenteeism and academic performance measured by each participating school providing a report on the academic performance of participating children using the Academic Performance Questionnaire (APQ) measures at baseline and months 3, 6 and 12

Overall trial start date


Overall trial end date


Reason abandoned (if study stopped)


Participant inclusion criteria

1. Studying in year 5 in the participating school and their age range is between 9 and 12 years
2. Self-reported non-tobacco users (i.e. smoked or smokeless)

Participant type


Age group




Target number of participants

Number of clusters: 68 (34 from each site), participants in each cluster: 1360

Participant exclusion criteria

1. Serious medical condition which is either life-threatening or requires regular hospitalisation
2. History of domestic violence and abuse (in any form)

Recruitment start date


Recruitment end date



Countries of recruitment

Bangladesh, Pakistan

Trial participating centre

ARK Foundation
Dhaka 1212

Trial participating centre

Aga Khan University

Sponsor information


University of York

Sponsor details

YO10 5DD
United Kingdom
+44 (0)1904 435138

Sponsor type




Funder type

Research organisation

Funder name

Wellcome Trust

Alternative name(s)

Funding Body Type

private sector organisation

Funding Body Subtype

International organizations


United Kingdom

Funder name

Medical Research Council

Alternative name(s)


Funding Body Type

government organisation

Funding Body Subtype

National government


United Kingdom

Funder name

National Institute for Health Research

Alternative name(s)


Funding Body Type

government organisation

Funding Body Subtype

National government


United Kingdom

Results and Publications

Publication and dissemination plan

The issue of SHS is already a national priority in Bangladesh and Pakistan. If SFI is found to be effective, the researchers will use advocacy, their existing linkages, and impact enhancement schemes to maximise the impact of their results (see below) in these countries and beyond.

Priority: Widespread SHS exposure in women and children and its impact has recently caught public and policymakers’ attention in Bangladesh and Pakistan. Two of the team’s recent papers on the topic were reported widely in national newspapers and TV channels. The Bangladesh government has responded by promising to prioritise this issue.

Advocacy: The researchers have partnered with NGOs within the two countries with expertise in advocating for tobacco control measures. Together, they will develop a dissemination strategy, which will target academic and non-academic audiences using a variety of media. In Bangladesh, their partner Work for a Better Bangladesh Trust has an expert advocacy team in reducing SHS exposure. In Pakistan, they are in liaison with the Director of Schools office within the Ministry of Education in Sindh, Pakistan who have extended their advocacy support.

Partnerships: Since its adaptation and piloting in the CLASS II trial, policymakers at the ministry and the WHO have shown a keen interest in the intervention and have been kept engaged through stakeholder events and policy briefs. Beyond the two countries, the study team is also connected to international funders and agencies supporting tobacco control efforts. These include the Global Alliance against Chronic Diseases (co-chair of the respiratory group), The Union (office bearers within tobacco control section), WHO Geneva, EMRO and SEARO offices and WHO FCTC secretariat (through existing partnerships - EU-H2020 TB & Tobacco consortium, NIHR_RESPIRE Unit and NIHR_ ASTRA Group). The researchers will use these partnerships to disseminate and seek support for their research findings.

Impact enhancement: the study team is currently leading an NIHR Global Health Unit (RESPIRE) and a Group (ASTRA), both based in south-east Asia. This gives them the opportunity to enhance their trial’s impact through their interface with relevant policymakers, professional bodies and third sector organisations, and also to extend this work to other countries such as India and Malaysia in due course. Through GCRF and ESRC schemes, the researchers have been successful in securing grants to enhance the impact of their research recently (TB & Tobacco plus). They use these schemes to demonstrate scale-up beyond trial sites and generate useful knowledge and momentum for a national scale-up. They will apply for these schemes towards the end of the CLASS III trial. They will also partner with governments and NGOs to seek implementation grants from funders like World Bank for a national/provincial roll-out. They will also support governments’ funding mechanisms (e.g. PC1 in Pakistan) to support scale-up.

IPD sharing statement
The datasets generated during and/or analysed during the current study are/will be available upon request from Prof. Kamran Siddiqi (

Intention to publish date


Participant level data

Available on request

Basic results (scientific)

Publication list

Publication citations

Additional files

Editorial Notes

05/10/2020: The recruitment start date has been changed from 01/10/2020 to 01/02/2021. 04/08/2020: The recruitment start date was changed from 17/08/2020 to 01/10/2020. 18/05/2020: Uploaded protocol (not peer reviewed) as an additional file. 11/05/2020: Trial's existence confirmed by Health Sciences Research Governance Committee (HSRGC) at The University of York.