Welding inside of a shop or garage can create fumes. But they can easily be removed from the area by using industrial-type fans, or you can make your own from a recycled forced-air furnace fan. Check with the installers in your area for used fans; the cost may not be more than about $25, or they might even give you one. Cover the intake and all moving parts with heavy metal mesh, and run the power cord through a switch for easy on-off control.
If you are in danger of paying your mortgage late, send your payment via overnight mail. The cost of doing so is probably much less than your late payment. For example, a 5% late penalty on a $1,000 payment is $50. Sending the payment via Federal Express will cost you less than $15.