pollutants

Mr Bojo Leju also says "produced water" - water released from the ground when oil is extracted and often containing hydrocarbons and other pollutants - was not properly treated.

The quality of the air can also deteriorate as pollutants build, especially in cities.

But residents in a large swath of Southern California should refrain from burning wood Friday — the destructive Mountain fire has thrown air pollutants into a frenzy, air quality officials said.

But the data about the levels of pollutants in these products shows that they are, in fact, quite safe.

The smog crisis is worse in winter, when cold, denser air traps pollutants closer to the ground.