The Senegalese capital is usually bathed in sunshine but for a fourth consecutive day on Friday the city on the Atlantic coast was shrouded in a pallid cloud.

A thick layer of dust blown in mainly from the Sahara has enveloped Dakar, forcing residents to don facemasks in scenes reminiscent of the Covid-19 pandemic.

Senegalese authorities warn of very poor air quality and have advised of health risks for vulnerable groups.

Weather forecasters say the situation will only begin to improve from Sunday.

There is a pollution peak linked to particles of desert origin from the Sahara, Aminata Mbow Diokhane, from the air quality management centre (CGQA), linked to the environment ministry, told AFP.

The whole of the West African country is affected by the phenomenon, she added.

Air quality in Dakar is very poor overall, the CGQA said in a statement on Thursday.

It said there were concentrations of particulate matter (PM10) exceeding 900 micrograms per cubic metre, or almost 20 times the maximum level recommended by the World Health Organization for 24-hour exposure.

Senegals National Civil Aviation and Meteorology Agency (ANACIM) says the health risk is high for people suffering from respiratory illnesses, young children and the elderly.

Such weather events are common in the country between mid-November and the end of March, Diokhane said.

They usually last for at least three days, said Ngor Ndiaye, a forecaster at ANACIM, adding that there would be cause for concern if the phenomenon went on for over a week. (AFP)