Unless alerted to the danger, the rescuers could faint and then die without ever realizing that they were being poisoned.
فَحِينَ يُصْبِحُ ٱلْهَوَاءُ مُلَوَّثًا ،‏ تَظْهَرُ عَلَيْهِ عَلَامَاتُ ٱلِٱضْطِرَابِ ،‏ حَتَّى إِنَّهُ يَسْقُطُ عَنْ مَجْثَمِهِ .‏