When you were driving to work late last week, you probably found yourself in a shroud of dense fog (OK, it was more like smog).

The fog greatly limited visibility, especially for drivers, reports Tuoi Tre (Vietnamese):

“I could not see further than 200 meters,” said a local resident after driving on the Hoàng Hoa Thám and Lăng Cha Cả flyovers in Tân Bình District.

So what’s behind the haze?

The phenomenon is a form of radiation fog caused by condensation in the air after a rainy night and usually melts away when the sun rises.

However, when sunlight is blocked by thick clouds, the fog lasts longer and it particularly bad when particles of pollutants attach themselves to the condensation, said the Head of the Southern Regional Hydro Meteorological Center.

We could sure use those metro and BRT systems right about now...