Gamma rays, like all electromagnetic radiation, travel at the speed of light in a vacuum. This speed is approximately 299,792,458 meters per second (m/s).

While the speed of light in a vacuum is a constant, the speed of light in a medium like air is slightly slower. However, the difference is negligible for practical purposes. Gamma rays interact very weakly with air, so their speed in air is essentially the same as their speed in a vacuum.

Therefore, the speed of gamma rays in air is approximately 299,792,458 m/s, just like in a vacuum.