Provided are hemoglobins having at least two chemical modifications that lower oxygen affinity, hemoglobins chemically modified by the addition of glyceraldehyde-3-phosphate, and hemoglobins having at least two specific chemical modifications. PEGylated versions of these hemoglobins are also provided, as are certain tetraPEGylated and diPEGylated hemoglobins. Methods of modifying a hemoglobin are additionally provided, as are methods of making a hemoglobin. Pharmaceutical compositions and blood substitutes using these hemoglobins are further provided, as are methods of treating a subject using these pharmaceutical compositions and blood substitutes.
