How does carbonic acid alone directly affect the pH of blood? â–º View Available Hint(s) Carbonic acid does not significantly affect blood pH. O Carbonic acid acts as a buffer by binding to a strong acid, producing a weak acid and salt, thus lowering blood p O Carbonic acid is a strong acid that dramatically lowers blood pH unless immediately neutralized by a buffer. Carbonic acid is a strong acid that, if added to blood, causes the pH to rise.