Regression analysis of satellite-derived fire spots and PM2.5 levels with respiratory cases in the Philippines

Abstract

Background and Objectives: Fire events emit pollutants that affect both air quality and respiratory health. This paper analyzed the interrelationship of satellite-derived fire spot density and annual average particulate matter (PM₂.₅) concentrations with the incidence of respiratory diseases.

Methodology: Monthly cases of influenza-like illness (ILI) and pertussis for 2017-2018 in all 17 regions of the Philippines were accessed from the Department of Health (DOH) Epidemiology Bureau. Reported cases per 100,000 population in the Philippines were linked with regional fire spot density and annual mean PM₂.₅ estimates from satellite data, Visible Infrared Imaging Radiometer Suite (VIIRS) active fire data, and Modern-Era Retrospective Analysis for Research and Applications, version 2 (MERRA-2), respectively. Linear, logistic, and Poisson models were used to analyze the association between the exposure and outcome variables.

Results and Discussion: The highest PM₂.₅ concentrations were observed in Regions IV-A and NCR but fire spot density was relatively lower. High PM₂.₅ levels can be due to other sources in these largely urbanized regions, such as vehicular emission, among others. Similarly, results showed inconclusive association between atmospheric parameters and incidence of ILI and pertussis. Among the variables, pertussis and PM₂.₅ may have the strongest association, albeit p>0.05. Other factors contributing to the increase of disease counts may be explored including vaccine rates and case reporting.

Conclusion: There is insufficient evidence to show that fire events and higher PM₂.₅ levels at a regional scale increased the risk for ILI and pertussis in 2017-2018. Further studies may be explored on how satellite-derived atmospheric data can be utilized in respiratory health studies.