Table 4 Summary of the bio-risk assessment conducted on 21 February 2018

Cleaning of walls and floors

Germogon targets Gram-positive and Gram-negative bacteria

Citriklenz targets Gram-positive and Gram-negative bacteria, yeast and moulds

none

Cleaning safety boots after underground shift

Vitroglo targets Gram-positive and Gram-negative bacteria, yeast and moulds

Used for sanitizing, cleaning and deodorizing sanitary ware as per manufacturers instruction

Laundering

Dirty and clean laundry segregated

Presence of dedicated washing machines for male and female clothes

No laundering of towels used in change rooms

Personal Protective Equipment

Provided before each shift

Sharing of gloves between workers

Workers washed protective clothing with untreated water and hung them for drying at the underground surface

Dressing of infectious wounds

Individually wrapped packs provided for each worker in the occupational health clinic

none

Waste disposal

Re-usable medical waste bins and sharps containers for disposal of biological waste

Waste collected and disposed by a subcontractor

none

Hand hygiene

All consultation rooms and change rooms had dedicated soap dispensers and basins for hand washing

No soap provided underground and untreated water was used to rinse hands and cool bodies

Drinking water quality

Week 1: TPC = 14,500 cfu/ml, faecal coliforms = 1 cfu/100 ml

Week 2: TPC = 6130 cfu/ml

Week 3: TPC = 1018 cfu/ml, faecal coliforms = 19 cfu/100 ml

TPC were above the limits of 1000 cfu/ml, coliform counts > 10 cfu/100 ml and presence of faecal coliforms

Engineering controls

Presence of ultraviolet germicidal irradiation lamps for infection control in change rooms

Some lights were non-functional and there was no evidence of service records and maintenance stickers

Environmental factors

Temperature and humidity monitored by an occupational hygienist underground

Temperature and relative humidity (dry bulb) ranging from 30.5 °C–31.3 °C and 61.1–91.0%