India's tallest rubbish mountain in New Delhi is on course to rise higher than the Taj Mahal in the next year, becoming a fetid symbol for what the UN considers the world's most polluted capital.

Hawks and other birds of prey hover around the towering Ghazipur landfill on the eastern fringe of New Delhi, stray cows, dogs and rats wander at will over the huge expanse of smoking filth.

Taking up the area of more than 40 football pitches, Ghazipur rises by nearly 10 metres a year with no end in sight to its foul-smelling growth.

According to East Delhi's superintendent engineer Arun Kumar, it is already more than 65 metres (213 feet) high. At its current rate of growth, it will be taller than the iconic Taj in Agra, some 73 metres high, in 2020.

India's Supreme Court warned last year that red warning lights will soon have to be put on the dump to alert passing jets.

It was not meant to be that way.

Ghazipur was opened in 1984 and reached its capacity in 2002 when it should have been closed. But the city's detritus has kept on arriving each day in hundreds of trucks.

"About 2,000 tonnes of garbage is dumped at Ghazipur each day," a Delhi municipal official said on condition of anonymity.

In 2018, a section of the hill collapsed in heavy rains killing two people.

Dumping was banned after the deaths, but the measure lasted only a few days because authorities could not find an alternative.

Garbage champions

Fires, sparked by methane gas coming from the dump, regularly break out and take days to extinguish.

Shambhavi Shukla, senior researcher at the Center for Science and Environment in New Delhi, said methane belching from the garbage can become even more deadly when mixed with atmosphere.

Leachate, a black toxic liquid, oozes from the dump into a local canal.

"It all needs to be stopped as the continuous dumping has severely polluted the air and ground water," said Chitra Mukherjee, head of Chintan, an environment advocacy group.

Residents say the dump often makes breathing virtually impossible.

"The poisonous smell has made our lives hell. People fall sick all the time," said 45-year-old local resident Puneet Sharma.

Protests do not work and now many people are leaving the district.

They say a plant that recycles waste into energy next to the dump increases their misery because the smoke it releases by burning trash is also poisonous.

Local doctor Kumud Gupta said she sees about 70 people, including babies, each day mostly suffering from respiratory and stomach ailments caused by polluted air.

A recent study said the dump was a health risk for people living within five kilometres (three miles), including for cancer.

Traffic clogged streets, heavy industry and annual burning of fields in regions around Delhi have already made the Indian capital notorious for its pollution.

A government survey conducted between 2013 and 2017 reported that Delhi saw 981 deaths from acute respiratory infection while more than 1.7 million residents suffered from infections.

And India's garbage mountains will only get bigger in coming years.

Indian cities are among the world's largest garbage producers, generating 62 million tonnes of waste annually. By 2030, that could rise to 165 million tonnes, according to government figures.

Chitra, of the Chintan group, said waste has become a huge challenge as India's growing wealth drives consumerism and the production of extra garbage that the country cannot dispose of properly.

When he took power in 2014, Prime Minister Narendra Modi launched Operation Clean India under which tens of thousands of public toilets have been built and new waste management rules were introduced in 2016.

But watchdogs, including the Supreme Court, have repeatedly accused Delhi's warring authorities — the region is controlled by one party while Modi's right wing party runs the city authorities — of not taking the waste crisis seriously.