The influence of the electron environment on the α decay is elucidated. Within the frame of a simple model based on the generalized Thomas-Fermi theory of the atom, it is shown that the increase of the electron density around the parent nucleus drives a mechanism which shortens the lifetime. Numerical results are provided for 144 Nd, 154 Yb and 210 Po. Depending on the nuclide, fractional lifetime reduction relative to the bare nucleus is of the order of 0.1÷1% in free ions, neutral atoms and ordinary matter, but may reach up to 10% at matter densities as high as 10 4 g/cm 3 , in a high-Z matrix. The effect induced by means of state-of-the-art compression techniques, although much smaller than previously found, would however be measurable. The extent of the effect in ultra-high-density stellar environments might become significant and would deserve further investigation.