A minimum number of sustainability criteria to be considered for choosing suppliers were established for each area, based on the amount and importance of the tender (if it is a tender with a significant impact on the Iso 69% Ohsas 18001 27% Corporate social responsibility 1% Iso 14001 3% Observatio n 13% Fairly unserious NC 11% Serious NC 43% Very serious NC 33% 312 environment, occupational safety, the quality of services provided to customers, the term or amount of the contract).