Pushing a metal rod that he uses to lift the sewer lid and a bamboo stick to unclog the pipes, Iqbal Masih walks along a narrow street in a busy neighbourhood in the southern Pakistani city of Karachi.

The deliberate dragging of the rod is meant to notify residents that Masih, a well-known face in the area, was there if anyone needed him.

"This is the only profession I know," said Masih, who has been a sanitation worker for more than 30 years.

"I know it's risky, unhygienic and people look down on us. But someone has to do it. If I don't do this, I do nothing. And that's worse," the 51-year-old told Al Jazeera, finishing off his cigarette and looking around to see if anyone had come out of their house.

Sanitation workers are individuals whose jobs can include cleaning toilets, emptying pits and septic tanks, cleaning sewers and manholes and operating pumping stations and treatment plants.

In many parts of the world, they often descend into the sewers without gloves or any other protective gear for very little money or respect. The work is usually accompanied by a set of risks, some of them life-threatening.

Everyone is advising #HandHygiene to prevent #COVID19outbreak. But who will take care of these hands of our #SanitationWorkers who are still cleaning our filth without any sick pay, proper protective gear and permanent contracts?#SafeHandsChallenge4SewperHeroes pic.twitter.com/dsb0Ko35as — Sweepers Are Superheroes (@sewperheroes) March 22, 2020

Masih is one of thousands undertaking these risks on a daily basis around the world, at a time when health experts and organisations are urging extra steps to ensure cleanliness and basic hygiene amid the coronavirus pandemic.

More than 18,500 people have died after contracting the coronavirus, with infections exceeding the 400,000 mark globally. Experts recommend washing hands with soap regularly, or using a sanitiser, as a protective measure against the new coronavirus.

But for millions around the world, including Masih, that's not an option.

"Sanitiser? I don't even know what that is. I clear up human waste with my bare hands. I wash my hands with water afterwards. Sometimes, people don't even let me do that, so I have to find water somewhere else."

The size of the sanitation workforce globally is not known, according to a joint report, titled Health, Safety and Dignity of Sanitation Workers, released in November last year by the World Bank, World Health Organization, International Labour Organization and WaterAid.

"Sanitation workers are among the most invisible and neglected in society," the report said. "These workers are often the most marginalised, poor and discriminated-against members of society who carry out their jobs with no equipment, protection or legal rights, often violating their dignity and human rights.

"It is only when those critical services fail, when society is confronted with fecal waste in ditches, streets, rivers, and beaches or occasional media reports of sanitation worker deaths, that the daily practice and plight of sanitation workers come to light."

Using a sanitiser is not an option for millions around the world [WaterAid]

Sanitation workers do not get paid much - on most days, Masih would earn less than 1,000 rupees ($6.5) - for doing this risky job.

Besides human faeces, needles, blades and broken glass, other sharp objects are thrown in the drains that can cause physical harm, said Raj Kumar, another Karachi-based sanitary worker whose name directly translates to "prince".

"Many people have died doing this work because there is so much chemical inside. People don't realise what they are throwing in their drains, and that ultimately someone has to pick it up," he told Al Jazeera.

In Burkina Faso, 45-year-old manual emptier Wendgoundi Sawadogo was wounded after a rock fell on his head as he emptied a pit. He, too, is fully aware of the dangers of the job but has to do it.

"There are risks and health problems that we run into while doing this work. Sometimes people throw syringes or shards of glass bottles in the pit. We have to spend money on tetanus vaccines, but if we have no money, what can we do," Sawadogo was quoted as saying in the report.

"Some even died. As far as I'm concerned, I'm lucky."

Because these workers are informal and undocumented, there are no available statistics on how many die while on the job.

No safety net

Back in Karachi, Prakash told Al Jazeera how he broke his leg when he fell down a sewage pipeline. For months now, he has been depending on a walker and has been unable to practice the only job he has ever known.

In the absence of any family support, health insurance or medical aid for sanitary workers, he has yet to treat his broken hip bone. He now begs on the streets of one of Karachi's most affluent neighbourhoods.

Experts recommend washing hands with soap regularly, or using a sanitiser. But for these workers, that's not an option [Zehra Abid/Al Jazeera]

In Pakistan, sanitary work is only offered to non-Muslims. In Burkina Faso, sanitation work is predominantly informal, revealed the report on sanitation workers, while in Kenya the market was "served by large numbers of informal operators and formal small operators".

It added that in India, some manual workers reported that they have been paid in food rather than money; manual emptiers in Senegal and Haiti reported low-income households failing to pay the agreed-on fee once they had completed the work.

"Sanitation workers carry out some of the most important roles in any society. It is shocking that they are forced to work in conditions that endanger their health and lives and must cope with stigma and marginalisation, rather than have adequate equipment, recognition and celebration of the life-saving work they carry out," said Tim Wainwright, CEO of WaterAid.

'When you die, you die'

Researchers have also warned that the health hazards associated with this work include "exposure to harmful gases such as methane and hydrogen sulfide, cardiovascular degeneration, musculoskeletal disorders like osteoarthritic changes and intervertebral disc herniation, infections like hepatitis, leptospirosis and helicobacter, skin problems, respiratory system problems and altered pulmonary function parameters".

Despite the warnings and the associated risks, many of these people go about their daily routine, knowing fully well the dangers that it accompanies.

"You have no paper to show that this is your profession," said Sawadogo, who has worked as a manual emptier for 15 years.

"When you die, you die. You go with your bucket and your hoe without recognition, without leaving a trace anywhere or a document that shows your offspring that you have practised such a job. When I think of that, I'm sad. I do not wish any of my children to do the work I do."

Additional reporting by Zehra Abid