After using harmful gases for years as a refrigerant in AC coaches, the Railways are replacing it with an ozone-friendly air-conditioning system in trains.

The 150-year-old organization was using refrigerant based on dichlorodiflouro methane gas, which is harmful to the ozone layer, causing its depletion.

"The dichlorodiflouro methane (R-12) is not environment-friendly.

"If it leaks during breakdowns or accidents, it will deplete the ozone layer around the stratosphere," a Northern Railway official said.

"The new refrigerants are more eco-friendly.

"We have converted 11 coaches equipped with conventional under-slung AC plants with eco-friendly refrigerants," the official said.

The depletion of the ozone layer, which blocks the entry of harmful infrared radiation of the sun towards the earth and thus acts as heat insulation for keeping the temperature of the earth under control, would disturb the ecological balance.