Days of dust from the Sahara desert have pushed air pollution levels to ten times the recommended healthy levels.
Winds have blown the dust over Malta with people waking up to hazy skies and dust-covered cars and windows over the last two days.
But the phenomenon has also had an impact on air quality, which can affect people with conditions like asthma.
Real-time air quality graphs show that the rate of PM10 - particulate matter smaller than 10 micrometers in size - hit an astonishing high of 514g/m3 (micrograms per cubic metre) on Wednesday morning.
The level of PM10 particles have spiked dramatically since Tuesday morning. Graph: ERAGuidelines by the World Health Organisation say that PM10 levels should not exceed an average of 45µg/m3 over a 24-hour period.
The readings, captured on the Environment and Resources Authority's substation in Għarb, show how particulate matter started rising early on Tuesday morning.
It increased rapidly from under 30µg/m3 at at the dead of night to over 100µg/m3 by 10am.
As the murky weather intensified, readings reached well over 400µg/m3 early on Wednesday morning, peaking at 503 µg/m3 at 10am.
Smaller dust particles, known as PM2.5 (because they are smaller than 2.5 micrometres in size) also increased over the past two days, rising tenfold from under 20µg/m3 on Tuesday morning to 121µg/m3 the following day.
PM2.5 and PM10 particles are both major contributors to Malta’s air pollution and a significant health hazard as they can evade people’s natural defences, such as a person’s nasal hair and throat, to enter the respiratory system and bloodstream.
Weather to clear by Thursday
Weather conditions are expected to clear by Thursday morning, with the MET office predicting that visibility will be "good" throughout Thursday and Friday as wind veers to the west, clearing the dust.
A spokesperson said the dust was down to a trough of low pressure which was extending from West Europe to Algeria and generated strong Southwesterly winds over the Sahara Desert.
"This causes very fine dust to get blown up in the atmosphere and carried along with the wind," the MET office said.
"In Malta we have been experiencing this dust in suspension from last Monday night, with the visibility falling below 3km on Tuesday and Wednesday.
"As the wind veers to a strong West Northwest, the sand is expected to move eastwards, and clear weather is forecast by Wednesday evening".
ERA officials previously told Times of Malta that Saharan dust and sea salt make up some 55% of the coarser PM10 particles in Malta, similar to levels detected in other Mediterranean islands such as Cyprus and Crete.
Meanwhile, studies show that a third of all PM2.5 particles recorded in Malta are brought about by natural phenomena, mostly a combination of Saharan dust blowing from Africa and sea salt spray from Malta’s coast.
Nevertheless, particulate matter readings are also heavily impacted by Malta’s perennial traffic problems, with readings often spiking during rush hour.
Of all ERA’s air monitoring stations, the Għarb station is the least impacted by traffic and construction, so it is most widely used to assess the impact of weather conditions on air quality.
A bather peers at his phone through the dust on Wednesday. Photo: Matthew MirabelliHow can you protect yourself from air pollution?
The European Environmental Agency estimates that poor air quality resulted in 238,000 premature deaths across Europe in 2020, many of them caused by exposure to the finer PM2.5 particles.
The UK's Asthma and Lung Association recommends limiting outdoor activity and exercise on high-pollution days and avoiding high-traffic areas by staying on quieter backstreets, if possible.
People stuck in slow-moving traffic should also keep their windows shut to prevent breathing in too much polluted air.
Face masks, while useful for protecting against other pollutants such as nitrogen dioxide, are largely ineffective at filtering out smaller dust particles, such as the more hazardous PM2.5 particles.