Milton grew quickly into a Category 5 storm Monday morning and is forecast to make landfall in Florida midweek.

The smoke particles have already reached high into the atmosphere, so they won't cause health problems or unusual odours. The most colourful sunset is expected on Tuesday evening.

The isotope measured in air in Tromsø for now is unknown. The isotope comes from a nuclear reactor, and is used in medial diagnostic.

A fire destroyed a Peter Pan Seafoods facility in Sand Point, Alaska, causing a pervasive smell of burning plastic from fishing gear stored on-site.