People suffering from asthma and other respiratory disorders must wear masks and stay indoors to avoid hazards caused by the volcanic ash erupting from Iceland, the World Health Organisation (WHO) has warned.

Daniel Epstein, spokesman of this UN agency explained that effects will begin to be felt when the ash descends and falls on several countries across Europe.

The most endangered are persons with respiratory problems who are warned to stay at home and use masks when outside, the experts said referring to a report of the UN news centre, Prensa Latina reported.

The volcanic ash, which contains ammonium, sulphates, sodium, carbon, several minerals and water, can reach bronchial periphery and cause difficulties in persons with asthma or other respiratory disorders, he said.

Meanwhile, the World Meteorological Organisation said it is unable to forecast the duration of the ash cloud in the atmosphere while eruptions of the Icelandic volcano still continue.

However, he said, the effects of this phenomenon on climate will be low due to temporary fall of temperatures because the ash blocks sun rays.