invention as described herein in some instances substantially eliminates emissions from the exhaust of drying devices that might normally be undesirably vented to atmosphere further in some instances an exhaust stack may be eliminated altogether thereby simplifying construction and reducing the cost of environmental testing in addition losses internal to the machine 10 may also be controlled for example the supply of the waste air from the drying device s or in some instances the mixture of the waste air from the drying device s and the portion of the heated air from the air handling device 800 may be controlled so as to match or slightly exceed the capacity of the vacuum system 900 in this manner seepage of room air into or excessive hot air leakage out of the web handling device s 75 can be avoided further with respect to the drying device s pressure sensors not shown may in some instances be placed within the hood of the respective drying device so as to monitor the pressure therein as such the supply of the waste air from the drying device s or in some instances the mixture of the waste air from the drying device s and the portion of the heated air from the air handling device 800 may be controlled such that the pressure within the hood is maintained at approximately atmospheric pressure and preferably slightly above ambient such a provision.