South Koreans were treated to a rare weather phenomenon yesterday when yellow snow fell in the capital and elsewhere across the country.

But the snow ? containing dust or sand from the desert regions of northern China ? could pose a health hazard, the country?s meteorological office warned.

?It?s tough to say whether it?s yellow sand mixed in snow or if it?s snow mixed in yellow sand,? a met official told Reuters.

A high concentration of the dust particles prompted the weather bureau to issue a yellow dust warning for the second time in three days. South Korea frequently gets sand or dust storms, but a yellow snow storm is very rare. ?I have never seen yellow snow falling before,? the met official said.

The agency said the yellow snow was a health hazard and officials have warned that the pollutants in the flurries included heavy minerals.