The bizarre incident, which happened in Glasgow, was one of a number of mishaps to befall HSE staff.
The government quango was asked under the Freedom of Information Act to provide details of accidents involving its own workers in the past three years.
It admitted staff had suffered a total of 21 accidents since 2010, 11 of them in the past year.
In 2012/13, at the same office, a member of staff in Aberdeen suffered "minor bruising" after striking their head against an object.
Another worker in the capital "sustained a strain injury whilst moving heavy object".
Over the three years there were six cases of people cutting their fingers on sharp objects.
Eben Wilson, of campaign group Taxpayer Scotland, said this showed there was a natural rate for incidents.
A spokesman for the Health and Safety Executive said: "HSE is a low risk organisation. Our reportable incident rate is less than a sixth of the average for comparable organisations. It is encouraging that the number of accidents and incidents reported across HSE declined by 20 per cent (in 2012/2013) compared to the previous year."