There's been a literal cloud hanging over the southeastern city of Port Harcourt, Nigeria. People's clothes have been covered in soot. The streets are covered in soot. Even residents' bed sheets are covered in soot.
"You're wiping your face with a handkerchief and everything is black. You're trying to clean your car and everything is black. Or you look at the soles of your feet and it is just pitch black," said Nubari, an environmental activist in Port Harcourt, Nigeria.
For the local people of Port Harcourt the soot is inescapable. It's made life hellish for residents.
"It's had a wide range of impact on many things," said 25-year-old local resident Ebenezar Wikina.
The region isn't unfamiliar to plumes of pollution. The Niger Delta is the country's oil producing region
and there are many oil refineries nearby.
However in the last few years, the situation has gotten much worse.
What causes the soot?
"Towards the end of 2015 it started, it wasn't this bad. People were complaining. But from between last year and this year, it has become much worse," said Nubari.
The cause of the soot has been something of a mystery. Although Nubari, like many activists and residents
, believe it is a result of the destruction of illegal oil refineries
"One of the causes is destroying products that are gotten from illegal crude refineries. When you burn them, it goes up into the atmosphere," said Nubari.
Despite health concerns, the people of Port Harcourt are trying to continue with life as normal.
"It's worse in the morning," said Nubari. "Irrespective of how bad the soot is at any given point in time, we go out."
"Light colored clothes are a problem. Most especially white and sky blue. They get stained easily and noticeably."
Residents have taken to Twitter to express their anger under the banner of #StopTheSoot
. Sandra Ezekwesili, a radio host at Nigerian station Cool FM, started the social media campaign.
Ezekwesili started the hashtag after a friend with asthma visited her and started to choke on the air. "On the Monday morning (after) I decided to tweet about it," said Ezekwesili.
Last Thursday residents took to the streets to protest against the soot.
"It was relatively successful. We started at around nine this morning," said Obuoforibo. "From what I've seen from our drone footage it's looking like there was somewhere between the high two hundreds to the low four hundreds (in attendance)."
Wikina told CNN the soot generally reduces towards raining season between April and October, but the "threat is still over us."
Port Harcourt was once known as the "Garden City" because of its parks and greenery. Now it's a very different picture.
In a statement released to CNN, Nigeria's Ministry of Environment said there is a link between the pollution and the operation of illegal oil refineries and their destruction.
In an attempt to lessen the soot, the federal and state governments have halted the destruction of illegal oil refineries by open burning.
"There is a direct correlation between the level, intensity and composition of the soot and illegal oil refinery activities, including their destruction in the Niger Delta," the statement read.
The soot has become the talk of the town among the city's residents who are worried about the effects of breathing in the pollutants.
"When they pick up their kid from school, you'll see parents with teachers talking about the soot. You go into an office and people are talking about the soot. And in church people are talking about the soot," said Andy Obuoforibo, a 37-year-old Public Policy Consultant and #StopTheSoot campaigner.
A joint mission by the UN and WHO to investigate the soot has also met with affected groups in Port Harcourt.