Freezing fog health warning issued after frosty phenomenon descends on Scotland
Freezing fog carries serious risks to respiratory and heart health, experts have warned.
Thousands of Scots were plunged into an arctic mist on Tuesday as freezing fog descended over the country. The Baltic conditions prompted the Met Office to issue a yellow weather warning for parts of Central Scotland, Tayside, Fife and Strathclyde until Wednesday morning.
Although many marvelled at the hanging mists and glistening surfaces brought on by the fog, health and travel authorities rushed to highlight the dangers that the frosty phenomenon can provoke.
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So what causes freezing fog to appear, and what health risks does it carry?
How does freezing fog form?
Fog forms when the land cools overnight beneath a clear sky and the heat radiates back into space. The cooler temperatures reduce the air's ability to hold moisture, which allows water vapour to condense into tiny water droplets - this eventually forms fog.
When temperatures are below freezing, the miniature water droplets in the air become supercooled. These freeze instantly when they come into contact with exposed surfaces, causing a a white deposit of feathery ice crystals, called a rime, to appear.
The characteristic ice is often seen on vertical surfaces that are exposed to the wind like trees, railings, and parts of cars. It is more common on higher ground like mountains and hills.
How can it harm our health?
The risk of traffic accidents spikes with the onset of freezing fog, as icy patches on the road create treacherous driving conditions. But beyond sparking travel chaos, the weather phenomenon can also increase the risk of dangerous respiratory complaints.
The chilly and moist conditions created by fog can prevent mucus from evaporating in the lungs, nose, and throat. This encourages bacteria and viruses to thrive, which rapidly leads to serious infections in the respiratory tract.
Dense fog can also trap particulates and contaminants, which can exacerbate conditions like asthma and allergic rhinitis when inhaled.
The cold conditions that lead to freezing fog also bring with them a heightened risk of deadly heart attacks and strokes. The British Heart Foundation warns that thousands more Brits die from heart and circulatory disease each year during the winter months, with the risk of health emergencies increasing when temperatures drop below 12C.
“When you are cold, blood vessels narrow in your skin and fingers and toes, so that less heat is lost,” explains Julie Ward, senior cardiac nurse at the British Heart Foundation. “But this narrowing creates more pressure in the rest of the circulation, meaning the heart has to work harder to pump blood around the body, increasing heart rate and blood pressure.”
Ward warns that the additional strain on the heart can lead to serious issues, particularly for people suffering from an existing heart condition. She also says that cold weather increases the risk of blood clots because blood becomes thicker as temperatures drop.
She adds: “The factors in your blood that cause it to clot become more concentrated and, at the same time, the natural anticoagulants, which help prevent clots, leave your bloodstream. This all makes a heart attack or a stroke more likely.”
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