The Unite Trade Union has written to Taoiseach Leo Varadkar calling for all building sites in Ireland to close immediately.
Its members are extremely concerned that they could potentially be exposing themselves to COVID-19.
Around 150,000 construction workers are currently working at sites across the country.
Unite says a significant number of them are working in limited space where social distancing is impossible, while noting that most sites have very limited hygiene facilities.
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