Where insulating glass units (IGUs) are being transported at very high or low altitudes, the extremes of pressure should be carefully factored to ensure no damage is caused to the IGU or its seals. Breather tubes are sometimes employed to balance out any difference in pressure whilst the glass is being transported, upon arriving at its final destination they are removed and the IGU can then be sealed permanently.

The IGU manufacturer should be consulted for more information about this.