Part of the UK will be hit by unusually high levels of air pollution and a dust storm from the Sahara on what is predicted to be the warmest day of the year so far with temperatures predicted to rise to 71.6F (22C).

Certain areas of south-east England are expected to face very high levels of pollution due to warm conditions leading to a build-up of local pollutants from sources such as traffic fumes, combined with more pollution from the continent and Saharan dust from the south.

Met Office forecaster Dan Williams said: “Friday is expected to be the warmest day with 69.8F (21C) or 71.6F (22C) possible.”

“Air is coming from the tropics and passing over land to the south of the UK before coming here.”

The problem is expected to be relatively short-lived however as Atlantic winds should disperse the polluted air and Saharan dust in the early hours of Saturday morning.

Nicola Maxey, spokesperson for the Met Office said: “There will be a little bit of Saharan dust in the air. Most people will not notice it unless it rains and is washed out of the air. If this happens then people may see fine particles of dust on their car windscreen for example.

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"This high pressure is moving away from the country to the east, which means the start of next week will be unsettled and changeable, with an increased risk of showers."

In areas that are facing high levels of air pollution, adults and children who suffer from lung problems or asthma, adults with heart problems and older people are advised to avoid strenuous activity.

Asthma sufferers should make sure that they carry their reliever inhaler round at all times as they may need to use them more often than usual.

Dr Penny Woods, chief executive of the British Lung Foundation said to The Telegraph: “This latest high pollution episode, coming so soon after the last, is troubling and could again put people living with respiratory conditions at risk of worsening symptoms.”

Air pollution on Oxford Circus in London was found to have exceeded the legal limit for the whole of 2015 in the space of just four days in January.

A report from Public Health England in April last year estimated that long term exposure to air pollution had an effect equivalent to 29,000 deaths a year in the UK.