BACKGROUND
Air pollution in most countries exceeds the levels recommended by the World Health Organization, causing up to one-third of deaths due to non-communicable diseases. Particulate matter (PM) and black carbon (BC) from mobile sources are the main contaminants.
OBJECTIVE
This research will aim to assess the relationship of exposure to air pollutants in microenvironments (PM2.5 and BC), with respiratory health and physical activity in users traveling by different types of transportation in Bogotá
METHODS
A mixed-methods study based on a convergent parallel design will be carried out with workers and students, the sample will include 350 healthy transport users traveling by different urban transportation modes in three main routes in Bogotá. The study will be performed into two components. First, a descriptive qualitative component focused on asserting the individual perception of air pollution by semi-structured interviews. Second, a cross-sectional study towards a) measuring the individual exposure to PM2.5 and BC using portable instruments (DustTrak and microAeth, respectively) b) measuring the pulmonary function by spirometry; c) assessing physical activity with Accelerometry. The analysis will include a concurrent triangulation and logistic regression. This protocol was approved by the technical and ethical committee of Instituto Nacional de Salud, protocol number 7, issued on April 4, 2019. Informed consent will be obtained from all participants before conducting the study.
RESULTS
The findings, from a public/academy/private perspective, will be useful for the conception, design, and decision-making process in both sectors: health and mobility. This study includes personal measurements of PM2.5 and BC during typical trips in the city, allowing to know in real-time the exposure to these contaminants in the major roadways. Also, the study compares two different lung tests to identify possible short-term respiratory effects. As a limitation, the protocol will include participants from different institutions in the city which are not necessarily representative of all healthy populations in Bogota. In this sense, it is not possible to draw causation conclusions. In spite, convergent parallel designs could be especially problematic concerning integration because they often lack a clear plan for making a connection between the two sets of results. In this case, this kind of design is left with two separate sets of results that may not be well connected. Nevertheless, the study counts with a procedure for how to integrate qualitative and quantitative data in the interpretation of the results and also a logistic regression. The time that participants have to live in the city will be taken into account; this will be controlled in the stratified analysis. Another limitation is the wide age range and working status of the participants. Regional pollution levels and episodes (PM2.5) will be handled as confounding variables. Since the use of masks is part of the strategy for prevention and control that can limit the spread of COVID-19, as a biosecurity protocol all participants will use surgical face masks during field measurements.
CONCLUSIONS
In this study, it is hypothesized the exposure to air pollutants in microenvironments in Bogotá, Colombia. To our knowledge, this is the first mixed-methods study focused on PM2.5, BC, and respiratory health effects in a city above 2.000 meters above sea level. This study will provide an integration of air pollution exposure variables and respiratory health effects in different microenvironments.
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