WMO scientists assess and monitor air pollutants such as ground-level ozone,smog, particulate matter, sulfur dioxide and carbon monoxide.

VOA: standard.2009.03.23

While the mayor was away, city residents struggled with choking smog and extreme heat in well-insulated apartments built to withstand extreme cold.

VOA: standard.2010.08.10

He says the farm helps ease Beijing's reliance on dirty energy that creates the capital's notorious smog.

VOA: standard.2010.08.03

Weather forecasters say that Moscow's smog may continue to recede on Wednesday.

VOA: standard.2010.08.10

Yet traveling back to smog-bound Beijing, past industrial factories, high-rise apartment blocks under construction,shopping malls and the ever growing number of cars, the future once more looks uncertain.

VOA: standard.2010.08.03