Residents of the U.S. Virgin Islands are well acquainted with the Sahara dust that heralds the arrival of summer in the region, but in June 2020 came “Godzilla” – a dust storm of such immense proportions that it extended from the Caribbean to the U.S. mainland.
The event – the largest African dust storm in 50 years – coincided with the global spread of COVID-19 and has prompted new research and public health initiatives by scientists in Puerto Rico.
While the Sahara mineral dust particles contain iron, nitrogen, calcium and phosphorous that help fertilize marine and terrestrial ecosystems, and the dry air that carries them acts to hinder the development of tropical storms, they also are a pollutant that affects the quality of the air that we breathe, a panel of scientists said on Thursday during a webinar hosted by the San Juan office of the National Weather Service.
“When we receive dust in the Caribbean region, most of the time we see exceedances in the parameters that are used to measure the quality of the air,” which both the U.S. Environmental Protection Agency and World Health Organization monitor, said Dr. Olga L. Mayol-Bracero, a professor and researcher in the Environmental Sciences Department and director of the Atmospheric Chemistry and Research Laboratory at the University of Puerto Rico – Rio Piedras Campus.
The Caribbean receives more than 40 million tons of Sahara dust every year, said Mayol-Bracero, who manages the Cape San Juan Atmospheric Observatory in the nature reserve of Cabezas de San Juan and the Cloud Forest Station in El Yunque, and is a pioneer in the territory in atmospheric chemistry and the impact of Sahara dust on climate and air quality.
Luckily, scientists can measure the concentration and structure of dust as it leaves the west coast of Africa through a network of stations in the Caribbean, Central America and the southern U.S. that use satellite data to determine the impact on cloud formations, precipitation and public health, Mayol-Bracero said. The stations also use air quality filters and chemical analysis of rainwater and cloud samples to better understand the impacts of the dust.
“There are still many uncertainties related to air quality and health,” said Dr. Pablo Méndez-Lázaro, an associate professor in the Environmental Health Department at the University of Puerto Rico, Graduate School of Public Health, who focuses on exploiting new technologies to benefit research on public health and vulnerable populations.
The EPA and WHO measure air quality by the amount of fine particulate matter in the air from sources such as smoke or, in the case of the Caribbean, Sahara dust, Méndez-Lázaro said.
They have thresholds for fine particulate matter, or PM2.5, so named because the particles are so tiny – 2.5 micrometers, or almost 30 times smaller than the diameter of a human hair – that they easily make their way into people’s respiratory tracts and lungs, according to the EPA.
While PM2.5 has long been recognized as a threat to health, new research is still shedding light on its impacts, Méndez-Lázaro said.
“Only three days ago, the journal ‘Nature,’ which is one of the most important scientific journals in the world, published new research on PM2.5 and health” that found its impact has been underestimated, “and even a slight exposure to PM2.5 is associated with brain damage,” Méndez-Lázaro said.
His recent research is focused on developing a visual air quality tool, a phone app of sorts, that would be easy for anyone to use to determine the risk to their health from PM2.5 on any given day. The idea was spurred by three days of hazardous air quality conditions in Puerto Rico during the “Godzilla” storm last June that coincided with a drought in part of the island, water rationing and the spread of COVID-19, Méndez-Lázaro said.
He aims to ensure that public health research and tools help the people most affected by the problem to be solved, said Méndez-Lázaro, who is partnering with 19 organizations in the fields of health, government, and academia on the project.
“We started co-designing an experimental tool looking to satisfy the needs of the users. The patients, the medical doctors, the government agencies. By no means is our tool pretending to replace the work that by law corresponds to the government agencies, such as the National Weather Service, when issuing an air quality statement; or the Department of Health, when issuing an advisory alert; or the Department of Natural Resources with the Office of Air Quality,” Méndez-Lázaro said. “We’re only looking to provide specific information, in a responsible way, and actionable format.”
The tool is still in the experimental stages, but its measures of daily PM2.5 air quality risks so far have been consistent with those of the EPA, Méndez-Lázaro said.
Other efforts at the university are focused on measuring the severity of symptoms in people with COVID-19 during Sahara dust events, with pulmonologists and medical doctors recently added to the team, Méndez-Lázaro said.
“We were wondering, what would happen if both of them are affecting the respiratory system at the same time,” Méndez-Lázaro said. “We are still working with that component. It was a little bit difficult to obtain access to the information from the hospitals. We finally did it, but it took us a lot of memorandums of understanding.”
Of particular interest is how much exposure to PM2.5 is reduced by wearing masks, which have become ubiquitous since the advent of COVID-19, but were hardly the norm before the pandemic, Méndez-Lázaro said.