As part of a BBC special investigation, Paul Vickers visited the Union Carbide plant in Bhopal - the scene of a disaster which claimed 4,000 lives 20 years ago - to see the extent of pollution today.
By Paul Vickers
Radio Five Live
Survivors of the Bhopal tragedy have been waiting for help for years
I knew I was in trouble as soon as I climbed through the vandalised window and into the umpteenth dilapidated shed I'd visited in the middle of the Union Carbide factory site at Bhopal.
Most of the buildings contained pollutants, but this one was particularly bad.
Rusting skips full of chemical waste, bags of toxic naphthalene, pools of mercury, even the raw ingredients for phosgene gas (horrible stuff as any student of WWI poets will tell you) all sat in a heap, variously evaporating and sublimating in the midday sun.
A pungent vapour burned the eyes. It was hard to see and even harder to breathe. After only a minute or two, I was retching so badly I had to stop recording.
Just outside, I sat for a few moments beside a herd of cattle, kept by local families for their milk, and watched them patiently chewing contaminated cud in the contaminated shade.
There's no problem getting animal or man into the site. Someone has pinched the wire from the security fence and flogged it in the market.
I was with a chemical engineer who once worked for Union Carbide and who wanted to show me what the company had left behind when it fled from the site in 1997.
He told me that if I had spent five minutes more in the shed I would have lost consciousness.
Aha! That is why he stayed outside with the cows.
I was making a radio documentary for the flagship Five Live Report and I knew that listeners needed to hear for themselves precisely what was still in these sheds.
Tape would give them that chance. A boffin reeling off a long and boring list of the chemicals I'd found, even a live one in the studio, simply wouldn't have conveyed any real sense of their true toxicity or, perhaps, say what they actually smelt like.
One of the luxuries of tape is that you can still go "on location" and let listeners hear just how poisonous these chemicals are. So back into the shed I went, and retched my other lung out.
But we didn't just want to show that the Union Carbide plant is still highly contaminated 20 years after the disaster, in spite of countless promises that the site had been cleaned up.
We also wanted to prove that chemicals from the site are still leaching into the soil and the water table, where they are poisoning a new generation of Bhopalis - people who suffer from a range of health conditions directly attributable to drinking contaminated water.
To do that, I had to find out where the wells around the site were placed and make sure that they were still being used for drinking water by the 25,000 or so people crammed into the shanty towns around the plant.
If they were still being used, I needed to take some samples.
Walking around their neighbourhood, gathering an impressive entourage of local children on the way, I eventually found a drinking well that was marked as contaminated, a red cap over the pump handle.
Sure enough, a few people were drinking from it. But as soon as the children saw what I was interested in, they started drinking from the well themselves, in spite of any amount of begging from me not to do so.
They wanted to show me what they thought I wanted to see - absolutely the last thing a journalist needs.
So instead, I had to sneak back several times over the next few days, spying from a window in a goat shed just to make sure that people were drinking from contaminated wells because they had to, and not because they thought a Brit reporter wanted to watch them do it.
I had to be similarly careful when it came to assessing the health of residents.
Everyone told me the same thing: they suffered from headaches, giddiness, fertility problems and some more serious conditions.
UNION CARBIDE'S REACTION
Union Carbide has disputed the results of the tests carried out as part of the BBC investigation
The company says when it handed the site back in 1998 it "found no evidence of groundwater contamination"
When the BBC presented details of the chemicals it found, Union Carbide said it was "not aware of any evidence to support such claims"
A pattern of symptoms was emerging, but I had to be sure that this was genuine, and not a result of the desire to please that must be, I think, one of the characteristics of Indian society.
This meant a lengthy check of medical records. Taking the samples was easy. It was the last hurdle-smuggling them through Customs - that gave me the worst nightmares.
Of course, I suspected they were poisonous but I didn't know how badly.
It turned out that water I had taken from a well that wasn't even marked as contaminated, had levels of highly toxic chemicals 500 times in excess of World Health Organisation limits.
My enduring horror for those last few hours, packing the bags to come home, was being stopped and searched at Bhopal Airport or Delhi International by Indian security staff.
"What's in these bottles?" demands the officer with the starched trousers and the ancient sten gun. "Er, drinking water, m'lud."
"Prove it!" comes the horrifying reply.