1.   Toxic emissions declined by half, days of dangerous smog levels declined by two-thirds.

2.   The dangerous smog conditions are expected to last through late Wednesday, said Airparif, a government body that monitors air pollution.

3.   The dangerous smog conditions are expected to last through late Wednesday.

4.   The dangerous smog conditions were expected to last through late Wednesday, said Airparif, a government body that monitors air pollution.