Weather officials confirmed on Thursday morning the onset of “exceptionally mild” weather, high levels of pollution and rain showers which, if they combine, could lead to the phenomenon known as “blood rain”.
Asthma-sufferers, the elderly and those with breathing difficulties were most at risk, with “moderate” pollution levels recorded this morning in South Wales, the Department for Environment, Food and Rural Affairs (Defra).
Defra said: "There is a risk of moderate or high levels of air pollution across parts of England and Wales on Thursday due to Saharan dust, although large uncertainties remain with the timing and amount of dust.
Saharan dust is lifted from its source in west Africa by strong winds and is blown northwards in weather systems heading towards the UK.
It is lifted by strong winds and can reach very high altitudes. From there, it can be transported worldwide by winds, covering distances of thousands of miles before getting caught in rain droplets in clouds, falling to the ground in rain. When the water evaporates, a thin layer of dust is left on surfaces, such as cars.
Dr Sotiris Vardoulakis, head of Public Health England`s Environmental Change Department, said: "While most people will not be affected by short term peaks in ambient air pollution, some individuals, such as those with existing heart or lung conditions, may experience increased symptoms.
Saharan dust cloud descends over UK
18 December 2015
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Health warnings have been issued for England and Wales as a potentially hazardous cloud of Saharan dust arrives in the UK.
