Updated: Nov 23, 2019
The Cameroon National Oil Refinery (SONARA), which was created in 1973 and inaugurated in 1981 is is a topping reforming refinery. It places at the disposal of the market the following petroleum products: butane, gasoline, jet fuel, kerosene, fuel oil, distillate.
The Limbe refinery has a theoretical capacity of 2,100,000 tons/year. It was conceived at first to treat light crude (Arabian light). However Cameroon currently produces heavy crudes and one notes an inadequacy between the existing tools in the refinery and the crudes available.
The SONARA Fire Disaster
Sadly, on Friday May 31, 2019, an explosion occurred around the Naphta separation zone of the National refining company, which is situated in Limbe, the South west region, leading to a fire outbreak (Government Press Release here).
Before we get intto the health and environmental effects of this disaster, it will be important we look at what exactly is crude oil and what happens during and after a refinery burn.
What Is Crude Oil?
Crude oil is a naturally occurring, unrefined petroleum product composed of hydrocarbon deposits and other organic materials. A type of fossil fuel, crude oil can be refined to produce usable products such as gasoline, diesel and various forms of petrochemicals. It is a nonrenewable resource, which means that it can't be replaced naturally at the rate we consume it and is, therefore, a limited resource.
Refineries separate the components of the mixture into various products: from small, simple molecules (LPG, gasoline) to medium molecules (jet fuel, diesel) to the heaviest molecules (fuel oil, wax, and asphalt). The crude mixture often has too little of some components (gasoline) and too much of others (fuel oil, asphalt). Refining separates the mixture components and can chemically alter them to create more of the wanted components and use up the unwanted ones. For example, catalytic cracking is a process to convert fuel oil or asphalt into gasoline.
Health Effects of A Refinery Burn?
It is important to note that a refinery burn can be controlled (in-situ) or uncontrolled (during a disaster). While the former usually involves a complete process of combustion where most of the dangerous chemicals are broken down to some acceptable level for our health, the latter poses a big threat to our health and the environment.
During the burn at SONARA, the fire created a large cloud or plume formed from the uncontrolled burning of oil. The plume contained many substances that are immediately dangerous to health and life. This includes carbon monoxide, hydrogen sulfide, sulfur dioxide, volatile organic compounds (VOCs), and particulate matter (PM).
If the burning involved the heavy components of the oil, like the asphalts, which are considered to be a hazardous air pollutant (HAPs), then the health effects coyuld be enormous, because asphalt includes polycyclic organic matter or polycyclic aromatic hydrocarbons (PAHs) - organic molecules that contain more than one benzene ring and have a boiling point greater than 212 degree F.
During an uncontrolled fire this material will vaporize (50%), burn (20%), or partially burn (30%). If it burns completely it will form carbon dioxide and water (which are danger-free chemicals). When it partially burns it forms a huge range of new molecules, including carbon monoxide, benzene, and multiple PAHs. In general the partially burned material is more toxic than the original material. A single, short term exposure to these compounds, such as inhalation of the plume from a fire, is usually not correlated with long term health problems. However,
inhaling such plumes of gas will create cold like symptoms – headache, runny nose and eyes, dizziness, coughing, and light headedness. The symptoms may take a week to go away. A healthy person will usually fully recover with no long term problems from such an incident.
The real harm to humans and animals occurs when these substances are taken in to the body. The harm to an individual depends on the length of exposure, the amount of exposure (the dose), and the habits of the person. The harm is also proportional to the amount of material taken into the body, with all routes (breathing, eating, and skin contact) adding to the overall dose. Certain groups of people will, in general, be more likely to be harmed (children, elderly, those with compromised immune system, smokers, and refinery workers).
Multiple exposures over long periods of time to even extremely small amounts is correlated with health problems such as cancer, heart disease, and respiratory problems. The exposure can occur through any combination of inhalation, ingestion, or skin contact.
The material that lands on the soil will most likely stay there until it is broken down by sunlight and microorganisms (about one year). The part that lands in waterways will be washed downstream and eventually be deposited in lake sediments, where it will also take about a year for them to be destroyed. Note that,
there will be some small fraction of these substances that will not be destroyed and will linger for much longer times - a major source of continuous exposure.
Unfortunately, these chemicals could pose a big problem even to the health of the ecosystem, altering it equilibrium.
Plants will absorb anything and everything they contact in the soil, water, or air (Bioremediation). Some plants will contain levels similar to their surroundings. Some plants will concentrate the materials above the background level, a process called biomagnification. It is not uncommon for a plant to concentrate a substance (organic or inorganic) to have levels ten times greater than the surrounding environment.
A Piece of Advice to The Inhabitants
Our humble advice to the people in the area of disaster (Limber and surrounding villages and towns) is that:
Plant flowers, not food in your garden this year, and wear disposable gardening gloves,
Do not let children or pets play in the dirt for at least a year.
No swimming/ fishing in lakes (standing waters) within the fallout zone for a month, rivers are probably ok, and
Fruit and nut trees will probably be ok.
Nkengacha Marcellous Agendia
President/CEO, HELP Foundation