Q COSTARICA — A mass of Saharan dust will reach Costa Rica in the coming days, reaching its peak concentration on Sunday, when air quality could deteriorate enough to affect the entire population.
The national weather service, the Instituto Meteorológico Nacional (IMN), warned that concentrations will begin to increase today, Friday, and will coincide with dry conditions, strong winds, and little rain—a combination that will favor the persistence of particulate matter in the atmosphere.
“It is expected to increase in the coming days. There is even a considerable increase expected on June 27, when the largest mass of dust will reach the region. This could affect not only people with asthma or respiratory problems, but practically everyone,” explained Daniel Poleo of the IMN’s Climatology Unit.
The IMN anticipates that concentrations will increase to between 60 and 80 micrograms per cubic meter, from Thursday’s 20 and 30 micrograms. These levels primarily pose a risk to people with asthma, allergies, respiratory illnesses, or the elderly.
In areas of the western Central Valley, such as Santa Ana, Belén, and Alajuela, concentrations could exceed 70 micrograms per cubic meter.
“The concentrations expected on Sunday are slightly higher. They are within the normal range for this type of event, but they do cause respiratory problems,” warned Poleo.
“People who don’t have any allergies or respiratory problems can still be affected. This can trigger migraines, headaches, and general malaise if a person remains exposed for one or two hours breathing this type of air,” he noted.
The IMN also warned that the presence of dust will reduce visibility, which could affect activities that depend on good atmospheric conditions, such as air navigation.
Strong winds, reduced rainfall
The IMN forecast predicts that the trade winds will remain moderate to strong until Monday, with gusts near 100 km/h in mountainous areas and high-altitude regions of the country.
The IMN explained that atmospheric stability will reduce rainfall in the coming days.
This condition will prevent the particles from being removed from the atmosphere, so they will remain suspended for longer.
“The only way for these particles to disappear is through rain. The raindrops wash them to the ground, but since we will have very little rainfall, the dust will remain in the air for several days,” Poleo indicated.
Costa Rica is currently experiencing a dry spell, and this dry period could be followed by a longer heat wave under the influence of El Niño.
“El Niño favors a greater occurrence of Saharan dust episodes and also of dry conditions. Therefore, it is possible that we will experience very similar events again during July,” he explained.
Saharan dust clouds regularly cross the Atlantic and sweep over the Caribbean into Central America. In Costa Rica, these phenomena typically trigger hazy skies, drier atmospheric conditions, and decreased air quality.
The suspended particulate matter often degrades air quality and can trigger respiratory issues. The dry air mass suppresses moisture, significantly reducing cloud cover and daily rainfall. Dust in the atmosphere traps heat and enhances a hazy, warm feel, leading to higher perceived temperatures.
How to Protect Yourself
- Stay Indoors: Keep windows closed when local particulate levels are high
- Filter Air: Use an indoor air purifier fitted with a high-efficiency filter.
- Wear Protection: Use a face mask outside if you are sensitive to dust, and wear eyewear to prevent severe eye irritation.
The IMN actively monitors these events. You can check their real-time warnings on the IMN Weather Warnings Dashboard.