Our first interaction with the late Ratan Tata was not pleasant. Delhi was choking with pollution, and our campaign on the right to clean air had been launched. Diesel was a fuel that was being indicted for emissions of tiny particulate matter PM2.5. This all was new in the mid-1990s, as science was discovering how fuel and vehicle quality, when improved, would lead to an unexpected outcome of smaller particulates, which could go deep into our lungs. So, my late colleague Anil Agarwal and I wrote about the dangers of diesel. And we promptly got a defamation