Association of asthma control with household particulate matter less than 2.5 microns, carbon monoxide and second-hand-smoking among children with asthma in Lagos, Nigeria: protocol of an ongoing observational cross-sectional study

Abstract Background Childhood asthma is increasing in developing countries, partly due to household air pollution (HAP). Asthma care aims for optimal symptoms control and minimal future risk of exacerbations, known as asthma control (AC). There is a high prevalence of suboptimal AC among Nigerian children and adolescents with asthma, with consequent increased risk of psychosocial, academic and financial burden and, sometimes, fatality. The adverse role of HAP on AC may be significant because of high levels of air pollutants like particulate matter less than 2.5 microns in aerodynamic diameter ( PM 2.5 ) and carbon monoxide (CO) in Nigerian homes, and prevalent exposures to second-hand smokes (SHS). Previous studies mostly evaluated the association between HAP and asthma with questionnaires, with no detectable association, possibly because of recall and social desirability biases. Thus, this study plans to determine the association between AC and objectively-quantified household PM 2.5 and CO and SHS (urinary cotinine) among children with asthma accessing routine outpatient care at the Asthma Clinics of the Paediatric Allergology, Dermatology & Respiratory Medicine Unit, and the Adult Respiratory Clinic of LASUTH. Methods Eligible children and adolescents (up to age 18 years) are being consecutively recruited into this observational cross-sectional study in which the following data are obtained: socio-demographics, medical history, AC, medication adherence, inhalation technique, parental asthma-related knowledge, lung function (peak flow, FEV 1 , home personal PEF variability), quality of life, urine cotinine level, household PM 2.5 and CO. Hierarchical multivariable logistic regression will be used to quantify the association of AC with PM 2.5 , CO and urinary cotinine while controlling for potential confounders. Discussion The findings from this study may be useful for education of families of children with asthma, advocacy with policymakers on air pollution control, as well as the design or strengthening of educational interventions to mitigate air pollution in households of children with asthma, for example counselling on cessation of smoking or use of cleaner cooking fuels. Trial Registration: Research project was registered at OSF with the project DOI: https://doi.org/10.17605/OSF.IO/2JS7P.