Studying the effect of particulate matter as SARS-CoV-2 transmitters

Abstract

Background: Studies of risk factors are especially valuable at this difficult time in the midst of a pandemic. High levels of particulate matter (PM) represent a serious risk factor on health. While this is a direct impact on health, indirect effects are worth considering, too.

Design and methods: The aim of this study was to investigate the role of PM in the transmission of viruses, especially SARS-CoV-2. Also, we sought to understand dynamics of PM in still air at high and low altitudes. Historic AQI and physical PM measurements were collected between August and September 2020 using air quality detector. Potential correlations between the number of total confirmed COVID-19 cases and average air quality index (AQI) from varied geographic locations were also assessed.

Results: Airborne PM levels were weakly associated with COVID-19 cases after analysing 77 territories. PM remained longer in the air at high altitudes compared to measurements made at sea level. This suggests that the link between PM and COVID-19 transmission could be aggravated in areas of high altitude.

Conclusions: This article highlights that particulate matter can be involved in SARS-CoV-2 transmission. However, confounding factors may have impacted the association between the two variables. These findings can serve as a foundation for future studies on the effect of air pollutants and fine particulate matter on viral transmission.

Figure 1.

PM measurements of Bakhour smoke in a closed room at two different altitudes. A time-course experiment was carried out at altitudes of 2700 m (A) and sea level (B). Dashed lines indicate the period needed for PM_2.5 concentrations to reduce from 440 μg/m³ to 300 μg/m³ (1 h at 2700 m and 30 min at sea level). Solid lines indicate the period needed for PM_2.5 concentrations to reduce from 200 μg/m³ to approximately 90 μg/m³ (2.5 hr at 2700m and 2 hr at sea level). Error bars represent ±SD of the mean. Due to high reproducibility in replicates (n=2), error bars are smaller than the symbols used to denote PM type. Therefore, error bars are not visible for many data points.

Figure 2.

Number of daily COVID-19 cases versus PM_2.5 measurements in Abha and Gazan Regions. A) Daily confirmed cases of COVID-19 recorded in Abha (the capital of Asir Region) and Gazan Region between August and September, 2020. B) PM levels in both regions between August and September 2020.

Figure 3.

Annual average AQI of countries and capitals as compared to total COVID-19 cases. By using historical AQI data, the number of total confirmed cases; expressed as percentages of the population (A) and as an overall number of cases (B) as of August 23^rd, 2020, were correlated with AQI averages from January to August, 2020 (n=77).