Taipei - The worst-ever dust storms from China forced air quality in Northern Taiwan sharply down Sunday, the Environmental Protection Administration said.

A total of 24 observation stations across the island recorded more than 1,000 micrograms of dust per cubic meter and a further ten showed values at damaging levels, according to the EPA. Skies turned a yellowish grey as there was no rain to wash away the dust, the Central Weather Bureau said.

The worst levels of pollution were recorded on the island of Matsu close to the coast of China's Fujian Province, in Keelung on the North Coast and in several Taipei City districts, EPA official Chu Yu-chi said.

Doctors advised people to limit outside activities to the barest minimum, and to wear masks or even goggles when riding a motorcycle. Patients suffering from breathing problems even before the storm should wait a few days until after it had left before resuming normal outside activities, reports said.

The number of patients recording breathing problems increased by 20 percent to 30 percent because of irritation by the dust, reports said. People wearing contact lenses felt irritation of the eyes, according to media reports quoting physicians.

The storms expanded to Central and Southern Taiwan during Sunday afternoon, especially in areas close to the coast, the EPA said. Visibility in Taitung on the southeast coast was reduced to 5 kilometers, according to reports.

The Central Weather Bureau however predicted the phenomenon would clear up gradually during the day Monday. The dust storms combined with a cold front to cut temperatures by 7 degrees, the bureau said.

The next cold front from China was predicted to arrive Wednesday evening and to stay until early Saturday, though it was not immediately known whether it would bring more dust. That was dependent on the situation in Inner Mongolia and other regions in the Chinese interior over the next two days, forecasters said.