Temporal trends in ambient fine particulate matter and the impacts of COVID-19 on this pollutant in Grenada, West Indies

ABSTRACT

Most Caribbean islands do not have air pollution surveillance programs. Those who live in these countries are exposed to ambient air pollution from a variety of sources including motor vehicles, ocean-going vessels, and Saharan dust. We conducted an air sampling exposure study in Grenada to describe daily changes in fine particulate matter (PM_2.5) pollution, and during Saharan dust episodes. Further, we assessed the impacts of COVID-19 public health interventions on PM_2.5 concentrations in 2020. Four fixed-site PurpleAir monitors were installed throughout Grenada, and one on the neighboring island of Carriacou. PM_2.5 was measured between January 6 and December 31, 2020. We classified each of these days based on whether COVID-19 public health mitigation measures were in place or not. Descriptive analyses were performed to characterize fluctuations in PM_2.5, and we assessed the impacts of public health restrictions on PM_2.5 using multivariate regression. The mean daily PM_2.5 concentration in 2020 was 4.4 μg/m³. During the study period, the minimum daily PM_2.5 concentration was 0.7 μg/m³, and the maximum was 20.4 μg/m³. Daily mean PM_2.5 concentrations more than doubled on Saharan dust days (8.5 vs 3.6 μg/m³; p < 0.05). The daily mean PM_2.5 concentrations were estimated to be 1.2 μg/m³ lower when COVID-19 restrictions were in effect. Ambient PM_2.5 concentrations in Grenada are relatively low compared to other countries; however, Saharan dust episodes represent an important source of exposure. Low-cost sensors provide an opportunity to increase surveillance of air pollution in the Caribbean, however their value could be enhanced with the development of correction algorithms that more closely approximate values from reference-grade monitors.

Implications: This study describes daily fluctuations in ambient PM_2.5 concentrations in Grenada in 2020. Overall, concentrations of PM_2.5 were low; however, we found that Saharan dust events cause daily exceedances in PM_2.5 above the current 24-hr limits of the World Health Organization. Moreover, the constructed models suggest that public health interventions to reduce the spread of COVID-19 reduced PM_2.5 concentrations by 27%.

Acknowledgment

The authors thank J. David Miller Ph.D. for helpful advice. The authors are also grateful to the Grenada Port Authorities, and the Meteorological Office at Maurice Bishop International Airport for providing the data.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

PurpleAir data are freely available online on their website. All enquiries about accessing additional data should be directed toward the corresponding author.

Supplemental material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/10962247.2022.2126555.

Additional information

Funding

Partial funding for this project was provided by the International Seed Funding Program administered by the Office of the Vice-President Research International at Carleton University.

Notes on contributors

Nicholas Dirienzo

Nicholas Dirienzo is an MSc graduate and Research Assistant at Carleton University.

Kerry Mitchell

Kerry Mitchell is an Associate Professor of Environmental and Occupation Health at St. George's University.

Martin Forde

Martin Forde is a Professor and Track Director for Environmental and Occupational Health at St. George's University.

Daniel Rainham

Daniel Rainham is a Professor in Health Promotion in the School of Health and Human Performance and a Research Scholar with the Health Populations Institute at Dalhousie University.

Paul J. Villeneuve

Paul J. Villeneuve is a Professor in the Department of Neuroscience at Carleton University.