Tetrafluoroethylene polymer, air filter medium, filter pack, and air filter unit

An air filter medium, comprising:

• a tetrafluoroethylene-polymer-drawn-porous-film having a thickness of 15.0 μm or less, and having a coefficient of variation of pressure loss of 5.0 or less,
• wherein the tetrafluoroethylene polymer has drawability and non-melt processability,
• wherein the tetrafluoroethylene polymer has a standard specific gravity of 2.158 or more,
• wherein the tetrafluoroethylene polymer has a ratio S2/S1 of 0.70 or more and 0.90or less, where S2represents an endotherm mJ/mg in a range of T0° C. or higher and 350° C. or lower, T0° C. is a temperature 2.5° C. lower than a temperature Tp° C. (340≤Tp≤345) at which a minimum point is given on a heat-of-fusion curve obtained by measuring an unbaked polymer for measurement having no history of heating to a temperature of 300° C. or higher using a differential scanning calorimeter at a temperature-increasing rate of 2° C./min, and S1 represents an endotherm mJ/mg in a range of 320° C. or higher and T0° C. or lower, and
• in the heat-of-fusion curve, a half-width HW that is a difference between temperatures at two intersection points of the heat-of-fusion curve and a line which is parallel to a baseline and passes through a half position of a vertical line extending from the minimum point at the temperature Tp° C. to the baseline is 6.0 or more.