The Impact of Outdoor Pm2.5 Pollution on Covid-19 Infectivity in Philippine Cities

Date of Award

5-1-2023

Document Type

Thesis

Degree Name

Master of Science in Environmental Science

First Advisor

Janina G. Tan, PhD

Abstract

The global spread of SARS-CoV-2 has been one of the major health emergencies in recent memory. Despite the growing body of research detailing the risk factors for COVID-19 patients, the specific links between air pollution and SARS-CoV-2 infection remain unclear, especially in the Philippine context. Understanding the effects of air pollution on COVID-19 infectivity rates can aid the environmental policymakers in updating or improving Philippine air standards. In this study, the effects of outdoor air pollution on COVID-19 infectivity in selected Philippine cities were investigated. Secondary data was obtained from the Department of Health, the Department of Environment and Natural Resources, and the Philippine Statistics Authority. Multiple Linear Regression was performed using 3-year average PM2.5 concentrations to assess effects of long-term PM2.5 exposure, while Generalized Linear Models (GLM) and Generalized Additive Models (GAM) were performed on daily PM2.5 concentrations to assess the effects of short-term PM2.5 exposure. Moreover, the effects of meteorological factors such as rainfall, average temperature & relative humidity were analyzed using GAM. Regression analyses show that 3-year average PM2.5 concentrations are a significant predictor of Case Fatality Rate (p < 0.05). This indicates that a 10 μg/m3 increase in the 3-year average PM2.5 concentration of a city will yield an expected 0.2 percentage points increase in the COVID-19 CFR of that city, holding all other variables constant. In the short-term exposure analysis, GAM plots show the non-linear and complex relationship between COVID-19 cases and the 7-day moving average of PM2.5 concentration, as evidenced by the relatively high effective degrees of freedom (EDF) of the GAM splines. In general, the effect of the 7-day moving average of PM2.5 concentration on COVID- 19 cases plateaus on values ranging from 10-25 μg/m3. Analysis of the effects of meteorological variables on COVID-19 cases reveal that rainfall, average temperature, and relative humidity are complex factors that have periodic effects based on their amounts or levels. Thus, it is acknowledged that weather plays a key role in COVID-19 outbreaks.

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