Assessing the Impact of Non-exhaust Emissions on the Asthmatic Airway (IONA) Protocol for a randomised three exposure crossover study

Background People living with asthma are disproportionately affected by air pollution, with increased symptoms, medication usage, hospital admissions and the risk of death. To date there has been a focus on exhaust emissions, but traffic-related air pollution (TRAP) can also arise from the mechanical abrasion of tyres, brakes, and road surfaces. Non-exhaust emissions (NEE) currently make up a greater proportion of TRAP by mass than exhaust emissions. With the increasing weight of vehicle fleets due to electrification, and increasing uptake of larger vehicles, it is likely that NEE will continue to be an increasing health challenge. These NEE remain unregulated and underexplored in terms of their health impacts, particularly in vulnerable groups such as people living with asthma. To date, few real-world studies have attempted to explore the impacts of non-exhaust emissions on human health. We therefore created a study with the aim of investigating the acute impacts of NEE on the lung function and airway immune status of asthmatic adults. Methods The IONA study will expose adults with asthma in random order at three locations in London selected to provide the greatest contrast in the NEE components within TRAP. Health responses will be assessed before and after each exposure, with lung function measured by spirometry as the primary outcome variable. Discussion Collectively this study will provide us with valuable information on the health effects of NEE components within ambient PM2.5 and PM10, whilst establishing a biological mechanism to help contextualise current epidemiological observations. Trial registration IRAS Number 320784 at ### Competing Interest Statement The authors have declared no competing interest. ### Clinical Trial 320784 (IRAS) ### Funding Statement This work is funded by Asthma + Lung UK as part of the Asthma UK Centre for Applied Research [AUK-AC-2012-01 and AUK-AC-2018-01] and The Health Effects Institute (USA) ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: This work has been reviewed by Queen Mary University Research Ethics Committee, The UK National Health Service Research Ethics Committee and the USA Environmental Protection Agency Ethical Rethical Review Board. I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes All data produced in the present study are available upon reasonable request to the authors