Users of diesel could be slapped with a higher fuel bill if new guidelines meant to reduce sulphur emissions on Kenyan roads and industries are gazetted.

The guidelines, developed by the National Environment Management Authority (Nema) and the Kenya Bureau of Standards (Kebs) aim to reduce the emissions because the gas is destructive to the environment.

When inhaled, the gas causes respiratory diseases and in extreme cases, it causes cancer.

When it combines with oxygen, it becomes corrosive.

The new guidelines could be gazetted by next month, said Muusya Mwinzi, the director general of Nema.

"Except for some delays at the Attorney General's offices, we would have liked them to be gazetted by now," he said.

Diesel is the principal source of sulphur, but if the emissions are to be reduced, there are several steps to be taken, which is time-consuming and expensive.

One of the options is to improve the capacity of the Kenya Petroleum Refinery Limited so that it can reduce the amount of sulphur in oil to agreeable levels.

The refinery at the moment does not have the capacity to do that, said Gulam Hussein Amjid, health, safety and environment adviser at the facility.

"We are upgrading the refinery and it will take about three years to be able to remove the sulphur to the acceptable levels," he said.

The refinery was designed to remove the gas only from the liquefied petroleum gas (LPG), petrol, and kerosene.

The other option for Kenya is to import high quality Murban oil that has less sulphur.

The Murban crude oil that Kenya imports from the Middle East has content of the gas.

This would mean that Kenya sources for crude from West Africa and Venezuela, which will, however, be more expensive because of higher freight costs.

But experts said this is not a viable option, and rooted for the upgrade of the refinery in Mombasa to produce the cleaner fuel.

"Restricting ourselves only to the kind of crude we can process is not good," said Mr Amjid.

Importing vehicles that pollute less was also an option, but contradicts with the renewed push to lower the age of second-hand imported vehicles from the current eight years to 12 years in line with the other East Africa Community members.

The drive to reduce sulphur emissions is being accelerated because of the findings by the Meteorological Department, which show the level of the gas in major towns was going up.

"The levels of air pollution especially in Mombasa and Nairobi are alarming," said Peter Bundi of the Meteorological Department.

He said the department has put new air pollution monitoring machines at University of Nairobi's Chiromo campus to enhance air quality monitoring.

According to Nema, up to 70 per cent of outpatient bills in Kenya is on diseases caused by pollution.

Sulphur oxide has adverse effects on human health and is corrosive to equipment.

Kenya's campaign is part of a wider strategy for developing countries, fronted by United Nations Environment Programme (Unep).

The UN agency has set the ball rolling towards achieving "clean vehicles" in mainly urban areas.

Under the Partnership For Clean Fuels and Vehicles, developing countries and private sector players work together to phase out traces of sulphur in diesel fuels.