Inversion worsening pollution in cities

The amount of harmful nitrogen dioxide in the air in Prague is now lower than it was at the weekend, but meteorologists warn that air pollution remains high. The weather in the Czech Republic over the past few days has been dominated by what is known as inversion. Alena Skodova has more:

Smog situation in Usti nad Labem

Those who are currently spending their winter holidays in the mountains must be enjoying themselves, as mountains areas in the Czech Republic are relatively warm - temperatures are above zero degrees Celsius and the sun is shining every day. Those who live in large cities on the other hand, are experiencing cold and wet weather, with temperatures below freezing point. All this thanks to what is known as 'temperature inversion', which Czechs know all too well, as it occurs every winter.

To find out exactly what inversion is, I spoke to Jan Moravcik from the Hydro-meteorological Institute in Prague.

"In meteorology, the term 'inversion' literally refers to a reversal of normal temperature patterns in the lower atmosphere. In wintertime, temperature inversion occurs when cold air close to the ground is trapped by a layer of warmer air. As the inversion continues, air becomes stagnant and pollution becomes trapped close to the ground."

Mr. Moravcik told me that last weekend, inversion was quite strong. Furthermore, the level of harmful emissions was higher than the permitted limits. But this occurred mostly in Prague and in the region of Usti nad Labem in Northern Bohemia, not all over the Czech Republic. The situation was not bad enough for concrete measures to be imposed. However, if pollution levels are really high, which mostly happens in industrial areas, inversion warnings are issued. There are different degrees of inversion warnings. When inversion is particularly bad children are kept indoors and people are asked to not use their cars. Fortunately this does not happen too often. But how can people protect themselves now, when no warnings have yet been issued but levels of harmful emissions are relatively high?

"People should stay at home and if they go out, they should not stay too long in the open air. People are also advised not to open windows for longer than five minutes and on no account should they practice either outdoor sports or any physical exercises, which make them breathe deeper and longer."

As for the weather forecast, the inversion is expected to stay for a couple of days. On Saturday, a warm front is expected to cross the Czech Republic and people in the cities might be able to breath a sigh of relief.