DAKAR (Thomson Reuters Foundation) - Five West African countries have agreed to stop importing toxic fuels from Europe in a move that could improve the health of more than 250 million people, according to the United Nations.

Nigeria, Benin, Togo, Ghana, and Ivory Coast have pledged to introduce strict standards to ensure they use cleaner, low-sulphur fuels for their vehicles, effectively stopping Europe from exporting its dirty fuels, the U.N. Environment Programme (UNEP) said.

European trading firms have been exploiting weak regulations in West Africa to export fuels with levels of sulphur up to 300 times higher than is permitted in Europe, campaign group Public Eye said in a report published in September.

Public Eye described the issue as a “ticking time bomb” as cities grow across Africa and populations boom in major hubs including Nigeria’s Lagos and Ghana’s Accra.

“West Africa is sending a strong message that it is no longer accepting dirty fuels from Europe ... they are placing the health of their people first,” said UNEP head Erik Solheim.

“Air pollution is killing millions of people every year and we need to ensure that all countries urgently introduce cleaner fuels and vehicles to help reduce the shocking statistics,” Solheim said in a statement released late on Monday.

Sulphur is responsible for deadly heart and lung diseases, health experts say.

The five countries have also agreed to upgrade the operations of their national refineries - public and privately owned - to improve the quality of their fuel by 2020, UNEP said.

Nigeria’s environment minister Amina Mohamed said the agreement would massively improve the air quality in its cities and allow the country to set modern vehicle standards.

“For 20 years Nigeria has not been able to address the vehicle pollution crisis due to the poor fuels we have been importing,” Mohamed said in a statement.

A combination of low-sulphur fuels and advanced vehicles emissions standards can reduce harmful emissions by up to 90 percent, according to the UNEP.

Outside of West Africa, Kenya, Tanzania, Uganda and Morocco have all increased fuel quality requirements in recent years.

But better quality drives up costs, and with many nations facing severe shortages in public finances, they are wary of angering people with higher pump prices, analysts say.