SAN JUAN/HAVANA – A good part of the Caribbean, from Cuba to Mexico, including Puerto Rico and the Lesser Antilles, this week is suffering the effects of a huge cloud of Sahara dust, a phenomenon that, although it occurs rather regularly, this year has blown across the Atlantic with an intensity not seen in half a century in some of the Western Hemisphere’s countries and causing “dangerous” impacts on air quality.
Experts say that the mass of hot, dry air loaded with possibly harmful dust that forms over the Sahara Desert, mainly in the summer, and then moves each year toward the Atlantic Ocean could cover an area the size of the United States and extend upwards to between 1,500 and 6,000 meters (4,900 to 19,700 feet) in altitude.
Although it is a recurring phenomenon – some years worse than others –, Puerto Ricans woke on Monday surrounded by a cloud with an intensity not seen on the island in 50 years, which caused authorities to label the air quality “dangerous” on Tuesday.
On that day, the Air Quality Index stood at 305, although the highest level reported in the past – in 2018 – was 154, a level called “unhealthy,” said Natural Resources and Environment Secretary Rafael Machargo.
This situation moved the government to ask everyone with respiratory problems, as well as children and the elderly, to avoid all outdoor physical activities.
The blanket of dust was so dense that it affected visibility across much of the island and in some areas the density was such that the sun looked significantly fainter, while in San Juan the dust could be felt in the air, motivating experts to recommend that people wear goggles along with the facemasks already recommended to combat the coronavirus.
Although the cloud moved on past Puerto Rico on Tuesday over the Gulf of Mexico, it cannot be ruled out that it might return to the island on the weekend or early next week.
In Mexico, the dust will reach its maximum concentration on Thursday and Friday over Campeche, Quintana Roo and Yucatan with effects including reducing rainfall, increasing temperatures, causing a foggy or misty sky, albeit with very little true cloud cover.
Mexico’s National Disaster Prevention Center (Cenapred) said that small quantities of dust “do not represent a significant danger for the public.”
However, it added that some sensitive people could be bothered by it, and the assistant health secretary, Hugo Lopez-Gatell, said that the dust increases the mortality level in people who suffer from chronic respiratory or cardiac problems.
At a virtual press conference, Dr. Luis Antonio Ladino, a researcher at the Atmospheric Sciences Center at the National Autonomous University of Mexico (UNAM), said that on Tuesday and Wednesday in the city of Merida, in Yucatan state, the dust particles in the air could be harmful, given that they were some eight times normal levels.
The arrival of the dust in eastern Cuba, where its intensity is considered to be the worst in decades, on Tuesday also spurred the authorities to issue alerts for higher temperatures and the possibility of increased respiratory illnesses and skin ailments.
On Thursday, however, the huge dust cloud is dissipating slowly although its influence remains as it continues to hinder rainfall and raises temperatures on the island, which has registered potential maximum thermometer readings for June.
In Guantanamo province in far eastern Cuba, which is feeling the worst effects of the dust, a temperature of 37.4 C (99 F) was recorded, very unusual for this time of year, while in Santiago de Cuba on Wednesday the thermometer stood at 30.2 C (86 F) and the dust limited visibility and “hid” the mountains of the nearby Sierra Maestra.
In 2019, Cuba registered its highest annual average temperature since 1951, with reports of over 28 C (82 F) as the summer average due – in part – to Sahara dust.
Various islands in the Lesser Antilles reported the worst dust “fog” seen in at least a decade, forcing local authorities to ask people with health risks to remain indoors.
Meanwhile, in Colombia authorities are expecting the dust to arrive in force on the weekend in Bogota and Medellin, where it has already begun to be noticed, and in the provinces of Cundinamarca and Boyaca.
Despite the health risks, experts also say that the dust can have beneficial effects on the environment, bringing mineral nutrients to the region that are good for fertilizing the ocean, while some scientists say that the iron content of the dust “is usually positive for agriculture.”