I can't have you spreading any contaminants you might be carrying.
The impact of the current policy on levels of contamination was assessed through the Delphi survey of experts on chemical contaminants and naturally-occurring toxicants.
They are ubiquitous environmental contaminants of considerable persistence.
Uppsala were noted for their care in removing contaminants.
Specially produced mixtures of CO 2 and trace contaminants were obtained from a specialist gas company.