I'm flying into Nepal next month for my first trip and I just got a Rough Guide. It makes it sound like the pollution in Kathmandu is almost guaranteed to make you sick, and they suggest you should only stay a couple of days max before getting out of the city.
I'm planning on staying about 3 months in Nepal so I had planned to stay about a week in Kathmandu, do some day trips out of the city, and get my bearings. However, if it really is as bad as they say, I'll change my plans and only spend a couple of nights there. I know travel guidebooks tend to be overly dramatic about everything, so it's hard to know how serious the problem really is.
So how bad do you find the pollution there?