Pan African Clinical Trials Registry
South African Medical Research Council, South African Cochrane Centre
PO Box 19070, Tygerberg, 7505, South Africa
Telephone: +27 21 938 0835 or +27 21 938 0967
Email: pactradmin@mrc.ac.za Website: pactr.samrc.ac.za
Trial no.: PACTR202607706610353 Date of Registration: 23/07/2026
Trial Status: Registered in accordance with WHO and ICMJE standards
TRIAL DESCRIPTION
Public title Personalised Air Quality feedback and financial support to promote cleaner cooking and reduce Indoor Air pollution among households: A 25-week community trial in Mbalmayo, Cameroon.
Official scientific title Effectiveness of Personalised Indoor Air Pollution Information compared to General Health Information on Household LPG Adoption and Indoor PM2.5 Reduction among biomass-dependent households. A 25-week Randomised field trial conducted in the Mbalmayo Community, Cameroon.
Brief summary describing the background and objectives of the trial Household air pollution (HAP) from biomass fuel combustion is responsible for approximately 3.2 million premature deaths annually, making it one of the leading environmental contributors to the global burden of disease, according to the World Health Organization. The principal pollutant of concern, fine particulate matter (PM2.5), penetrates deep into the respiratory tract and bloodstream, causing acute lower respiratory infections, chronic obstructive pulmonary disease, ischaemic heart disease, stroke, and lung cancer. In peri-urban Cameroon, where the majority of households rely on firewood and charcoal for cooking, indoor PM2.5 concentrations routinely exceed WHO guideline values, disproportionately affecting women and children who spend the most time near cooking fires. Despite the availability of Liquefied Petroleum Gas (LPG) as a cleaner alternative, adoption has remained slow due to a combination of financial constraints and behavioural barriers, including risk perception, habit, and resistance to change. To address the financial dimension, all three arms of this study incorporate LPG voucher support to reduce the immediate cost of fuel refilling, thereby isolating the effect of information type on adoption behaviour. This 25-week pilot randomized field trial evaluates whether personalised indoor air pollution information derived from each household's own real-time PM2.5 sensor readings is more effective than general health information in promoting LPG adoption and reducing indoor PM2.5 exposure among biomass-dependent households in Mbalmayo, Cameroon. Forty-five households are randomized across three arms: personalised IAP information with LPG voucher support, general information with LPG voucher support, and a control group with LPG support. Findings will contribute experimental evidence on the role of information personalisation in clean cooking behaviour change and inform the design of a larger confirmatory trial.
Type of trial RCT
Acronym (If the trial has an acronym then please provide)
Disease(s) or condition(s) being studied Indoor Particulate Matter 2.5 reduction ,Respiratory
Sub-Disease(s) or condition(s) being studied
Purpose of the trial Prevention
Anticipated trial start date 10/08/2026
Actual trial start date
Anticipated date of last follow up 01/02/2027
Actual Last follow-up date
Anticipated target sample size (number of participants) 45
Actual target sample size (number of participants)
Recruitment status Not yet recruiting
Publication URL
Secondary Ids Issuing authority/Trial register
No.4395.CRERSHC.2026 CENTRE REGIONAL ETHICS COMMITTEE FOR HUMAN HEALTH RESEARCH
NIHR25203 THE ROYAL SOCIETY OF TROPICAL MEDICINE AND HYGIENE
STUDY DESIGN
Intervention assignment Allocation to intervention If randomised, describe how the allocation sequence was generated Describe how the allocation sequence/code was concealed from the person allocating the participants to the intervention arms Masking If masking / blinding was used
Parallel: different groups receive different interventions at same time during study Randomised Simple randomization using a randomization table created by a computer software program Sealed opaque envelopes Open-label(Masking Not Used)
INTERVENTIONS
Intervention type Intervention name Dose Duration Intervention description Group size Nature of control
Experimental Group Personalized Indoor Air Quality Information and LPG Voucher support Baseline questionnaire administered during Weeks 1 and 2; four weekly personalised PM2.5 feedback sessions delivered in batches from Weeks 3 to Week 14; LPG voucher issued once at baseline; transitional survey administered to any household adopting LPG before Week 23; end-line questionnaire and PM2.5 measurement during Weeks 23 to 25. 25 weeks Households receive a PurpleAir low-cost PM2.5 sensor installed in their primary cooking area. The sensor continuously collects indoor air quality data onto an SD card. At the start of each subsequent week over four weeks, the field worker retrieves the SD card, downloads and analyses the PM2.5 trend data, and produces a personalised information leaflet displaying the household's specific indoor PM2.5 concentrations relative to the WHO guideline value of 15 µg/m³. This leaflet is shared with the household at the beginning of the following week, making pollution risk vivid, proximate, and personally attributable. This process is repeated for four consecutive weeks, generating four personalised feedback sessions in total. All households in this arm also receive LPG voucher support identical to the other two arms. 15
Experimental Group General Indoor Air Pollution Health Information with LPG Voucher Support Baseline questionnaire administered during Weeks 1–2; single general health information leaflet delivered once at the end of baseline (Week 2); LPG voucher issued once at baseline; transitional survey administered to any household adopting LPG before Week 23; end-line questionnaire and PM2.5 measurement during Weeks 23 to 25. 25 weeks Households in this arm receive a standardised general health education leaflet on the risks of indoor air pollution from biomass combustion and the health and environmental benefits of LPG adoption, delivered by a trained field worker in a single structured session at the end of the baseline period (Week 2). No PurpleAir sensor is installed in these households. Following the single information session, households enter an observational period during which no active intervention contact occurs. This arm serves as the active comparator against Experimental Group 1, isolating the specific contribution of information personalisation to clean fuel adoption and PM2.5 reduction by holding the type of contact, financial support, and general health messaging constant across both arms. All households in this arm receive LPG voucher support identical to Experimental Group 1 and the control group. Endline data collection is conducted during weeks 23 to 25, with an additional transitional survey administered to any household that adopts LPG before week 23. 15
Control Group Control Single voucher given at baseline 25 weeks Households in the control arm receive LPG voucher support to offset the cost of LPG fuel refilling but receive no information intervention of any kind. Baseline and end-line data are collected using structured questionnaires and PurpleAir PM2.5 sensors. The control group serves as the counterfactual baseline against which both intervention arms are evaluated, with the voucher held constant to ensure that financial access does not confound the comparison. 15 Active-Treatment of Control Group
ELIGIBILITY CRITERIA
List inclusion criteria List exclusion criteria Age Category Minimum age Maximum age Gender
Households located within the selected study site and communities Households with the principal cook aged above 25years Households that exclusively use Biomass for cooking Household who are willing to have an air quality monitoring device installed in their cooking area Households already using LPG or other clean cooking technologies Households currently participating in another intervention or study on clean cooking Households in which the head of the house or main cook is a smoker Adult: 18 Year(s)-44 Year(s),Aged: 65 Year(s)-79 Year(s),Middle Aged: 45 Year(s)-64 Year(s) 25 Year(s) 65 Year(s) Female
ETHICS APPROVAL
Has the study received appropriate ethics committee approval Date the study will be submitted for approval Date of approval Name of the ethics committee
Yes 06/07/2026 Centre Regional Ethics Committee for Human Health Research
Ethics Committee Address
Street address City Postal code Country
Yaounde Yaounde B.P1937 Cameroon
OUTCOMES
Type of outcome Outcome Timepoint(s) at which outcome measured
Primary Outcome Change in indoor PM2.5 concentration (µg/m³) between baseline and end-line, measured using PurpleAir low-cost PM2.5 sensors installed in the household cooking area week 1-2 Pre-Intervention, week 23-25 post Intervention
Primary Outcome LPG adoption intensity. Proportion of cooking events conducted using LPG at endline, measured by self-reported fuel use diary and structured questionnaire. Week 23-25 post intervention
Secondary Outcome Change in self-reported respiratory symptoms and health outcomes between baseline and endline, measured using a respiratory symptom questionnaire Week 1-2 Pre intervention, week 23-25 post intervention
Secondary Outcome Change in behavioural resistance and risk perception score between baseline and end-line week 1-2 Pre Intervention, week 23-25 Post Intervention
RECRUITMENT CENTRES
Name of recruitment centre Street address City Postal code Country
Mbalmayo Community Community-based Area of Mbalmayo Mbalmayo Cameroon
FUNDING SOURCES
Name of source Street address City Postal code Country
The Royal Society of Tropical Medicine and Hygiene Northumberland House, 303-306 High Holborn London London United Kingdom
SPONSORS
Sponsor level Name Street address City Postal code Country Nature of sponsor
Primary Sponsor Royal Society of Tropical Medicine and Hygiene Northumberland House, 303-306 High Holborn London WC1V 7JZ United Kingdom Charities/Societies/Foundation
COLLABORATORS
Name Street address City Postal code Country
Afuge Akame Junior Ramsy University of Buea Buea Cameroon
Mbatchou Ngahane Bertrand Hugo Douala General Hospital Douala B.P 4856 Cameroon
CONTACT PEOPLE
Role Name Email Phone Street address
Principal Investigator Mary Chiara Nkombu Tendong marychi.mc48@gmail.com +237651253067 Beedi Douala
City Postal code Country Position/Affiliation
Douala Cameroon Research Assistant
Role Name Email Phone Street address
Public Enquiries Tafon Princewill tafonprincewill@yahoo.com +237676032670 Bonaberi
City Postal code Country Position/Affiliation
Douala Cameroon Health Economist
Role Name Email Phone Street address
Scientific Enquiries Afuge Akame Junior Ramsy afugeakame@gmail.com +237675897555 University of Buea
City Postal code Country Position/Affiliation
Buea P.O B 063 Cameroon Lecturer
REPORTING
Share IPD Description Additional Document Types Sharing Time Frame Key Access Criteria
Yes Individual participant data (IPD) will not be publicly shared in raw form due to participant confidentiality obligations and the informed consent terms under which data were collected. Anonymised and aggregated summary results will be made available within 12 months of study completion in accordance with WHO requirements. Researchers wishing to access anonymised individual-level data for collaborative or replication purposes may submit a formal written request to the Principal Investigator for consideration on a case-by-case basis. Informed Consent Form,Statistical Analysis Plan,Study Protocol Anonymised summary results will be made available within 12 months of study completion (anticipated by February 2028). Individual participant data will not be shared Access to anonymised summary data is available upon reasonable written request to the Principal Investigator at marychi.mc48@gmail.com. Requests will be considered based on the scientific merit of the proposed use, compatibility with participant consent terms, and compliance with applicable data protection regulations. No commercial use of study data is permitted.
URL Results Available Results Summary Result Posting Date First Journal Publication Date
No
Result Upload 1: Result Upload 2: Result Upload 3: Result Upload 4: Result Upload 5:
Result URL Hyperlinks Link To Protocol
Result URL Hyperlinks
Changes to trial information
Section Name Field Name Date Reason Old Value Updated Value
Eligibility Age group 16/07/2026 Reviewer comment Adult: 18 Year(s)-44 Year(s), Middle Aged: 45 Year(s)-64 Year(s) Adult: 18 Year(s)-44 Year(s), Middle Aged: 45 Year(s)-64 Year(s), Aged: 65 Year(s)-79 Year(s)
Section Name Field Name Date Reason Old Value Updated Value
Intervention Intervention List 16/07/2026 Reviewer comments Control Group, Control, Single voucher given at baseline , 25 weeks, Households in the control arm receive LPG voucher support to offset the cost of LPG fuel refilling but receive no information intervention of any kind. Baseline and end-line data are collected using structured questionnaires and PurpleAir PM2.5 sensors. The control group serves as the counterfactual baseline against which both intervention arms are evaluated, with the voucher held constant to ensure that financial access does not confound the comparison., 15, Active-Treatment of Control Group
Section Name Field Name Date Reason Old Value Updated Value
Outcome OutCome List 16/07/2026 Reviewer comment Primary Outcome, Change in indoor PM2.5 concentration (µg/m³) between baseline and end-line, measured using PurpleAir low-cost PM2.5 sensors installed in the household cooking area, week 1-2, week 3-14, week 23-25 Primary Outcome, Change in indoor PM2.5 concentration (µg/m³) between baseline and end-line, measured using PurpleAir low-cost PM2.5 sensors installed in the household cooking area, week 1-2 Pre-Intervention, week 3-14 during intervention, week 23-25 post Intervention
Section Name Field Name Date Reason Old Value Updated Value
Outcome OutCome List 16/07/2026 Reviewer comment Primary Outcome, Change in indoor PM2.5 concentration (µg/m³) between baseline and end-line, measured using PurpleAir low-cost PM2.5 sensors installed in the household cooking area, week 1-2 Pre-Intervention, week 3-14 during intervention, week 23-25 post Intervention Primary Outcome, Change in indoor PM2.5 concentration (µg/m³) between baseline and end-line, measured using PurpleAir low-cost PM2.5 sensors installed in the household cooking area, week 1-2 Pre-Intervention, week 23-25 post Intervention
Section Name Field Name Date Reason Old Value Updated Value
Outcome OutCome List 16/07/2026 Reviewer comment Primary Outcome, LPG adoption intensity. Proportion of cooking events conducted using LPG at endline, measured by self-reported fuel use diary and structured questionnaire., Week 23-25 Primary Outcome, LPG adoption intensity. Proportion of cooking events conducted using LPG at endline, measured by self-reported fuel use diary and structured questionnaire., Week 23-25 post intervention
Section Name Field Name Date Reason Old Value Updated Value
Outcome OutCome List 16/07/2026 Reviewer comment Secondary Outcome, Change in self-reported respiratory symptoms and health outcomes between baseline and endline, measured using a respiratory symptom questionnaire, Week 1-2, week 23-25 Secondary Outcome, Change in self-reported respiratory symptoms and health outcomes between baseline and endline, measured using a respiratory symptom questionnaire, Week 1-2 Pre intervention, week 23-25 post intervention
Section Name Field Name Date Reason Old Value Updated Value
Outcome OutCome List 16/07/2026 Reveiwer comment Secondary Outcome, Change in behavioural resistance and risk perception score between baseline and end-line, week 1-2, week 23-25 Secondary Outcome, Change in behavioural resistance and risk perception score between baseline and end-line, week 1-2 Pre Intervention, week 23-25 Post Intervention