PORT HARCOURT, NIGERIA - Nigerian health authorities say the country's life expectancy is among the worst in the world, with influenza and pneumonia leading causes of death. In southern Nigeria's Cross River state, severe air pollution is increasing the cases of respiratory diseases.

Port Harcourt resident David Tolu-Adamu knows. Before leaving for work each day, he dons his face mask.

Tolu-Adamu says it's a measure he has been taking since long before the coronavirus pandemic to filter out the sooty air.

'Constantly on a daily basis, year in year out, we have issues with black soot," he says. "We breathe in this harmful substance in our day in, day out, in our sleep, while we work, when we exercise.'

Wearing a face mask is a common practice for many in the oil-rich city polluted by the activities of illegal oil refineries, flaring gas and the burning of garbage and tires. The pollution generated by soot escalated in 2016.

Health authorities say the soot is increasing respiratory ailments in the state and that some 23,000 people have been affected in the last five years.

This month, state authorities began addressing the problem in the affected areas by stopping and criminalizing the illegal refinery practices, says a local government head, Samuel Nwanosike.

'If the actions were not affecting our health, then we wouldn't bother," he says. "We are the ones here, we are the ones dying, we're the ones feeling the pain. I am here every day in Ikwerre local government (area), sometimes I open my door, everywhere is turned dark; meanwhile there's supposed to be sunshine."

Health authorities say the country's life expectancy of 54 years of age ranks among the five lowest in the world.

Respiratory illnesses such as influenza and pneumonia are leading causes of death. Globally, almost 300,000 people died from these ailments in 2018, according to World Health Organization estimates cited by the group World Life Expectancy.

Rivers State authorities blame soot pollution for making the problem worse. Since the start of this year, they have cracked down on illegal refinery operators, arresting more than 20 and shutting down many bases.

Critics accuse state authorities of not doing enough to curb pollution.

'The government is only interested in the proceeds of oil and gas, but they are not interested in the people; they're not interested in the environment," says Ibiosiya Sukubo, a local chief in Port Harcourt. "It has put our youths into the creeks, to the breaking of pipes and creating artisanal refineries, forgetting the additional health hazards and implications. We are just victims of circumstance.'

For now, Rivers State authorities say they will continue their crackdown on illegal refineries while looking for other ways to keep residents safe from the soot.