It has been two years since China Daily last interviewed 31-year-old Zhang Chao. The Beijing-based micrograph enthusiast still wears the same hair style, even the same coat.

But one thing is very different: He's become a celebrity in cyberspace almost overnight, after his pictures, which depict what the rampant smog in Beijing looks like under his microscope, spread like a virus on China's major micro-blogging site Sina Weibo, since he posted them last Friday. Now the media is hounding him for interviews.

"Why do I become famous when I took pictures of the smog?" he asks with a wry smile. "I have taken numerous pictures of beautiful nature whenever I have spare time, but there are no more than 10 interview requests for me every year before. Now, I have to answer dozens of phone calls from media every day.