Tokyo Electric Power Co. has expanded the areas where employees at the Fukushima No. 1 nuclear plant can work without masks as radiation levels continue to decline.

The move, taken at the end of May, is expected to reduce cases of heatstroke for some 3,000 workers at the plant.

Since the mega-quake and tsunami that triggered core meltdowns at the plant in March 2011, workers have been obliged to wear masks that filter radioactive particles from the air. But when combined with a hazmat suit, the masks make it difficult to breathe, especially in the summer.

The summer of 2011 saw 23 Tepco workers felled by heatstroke. Last year the figure was seven.

Tepco has been expanding the areas where masks aren't needed since November 2011, after radiation levels began to decline.

The latest move in May increased that area to about half of the plant's premises.

Translated by The Japan Times