We have extensive threads on ventilation so of course you will be pointed to read them.
There is one that has a 5 star rating so it is a little easier to find and it has several links to very thorough discussions that you really should read (probably twice because they can be a little technical).
There are two things to keep in mind about melting glass.
One is that some of the chemicals used to give the glass its color like copper, silver, cobalt, cadmium and other 'heavy metals' can be released as a gas when you melt the glass and deposited on your bench, the door frame, the floor and your hand tools unless you take specific efforts to control it.
The other is that burning fuel produces its own types of gases that are not friendly to the health of creatures that breath. These gases also require that you take specific efforts to control it.
Think of the torch as a spray bottle that is constantly spraying a very fine mist of dust like the dust mites you can see in the sunshine coming in through the window.
If you don't create a way to make them go where you want them to they will just settle on to every surface within a 20 foot circle.
If you have the garage doors open and the wind is blowing at a steady 5 miles an hour you can pretty much be sure that these "dust particles of the torch gases" are going to out the door and mix with the air outside and no longer be hazardous to things that breath because they will be diluted by the large amount of air outside.
But if the wind stops blowing then that cloud of dust is going to settle every where.
And if the wind changes direction and starts blowing that cloud of gas into your face you really don't want to be inhaling that stuff.
So to answer the question: No.
It wont be safe for you to do it that way and even a box fan will not help because a 4 mile an hour wind will blow the air from the front of a box fan around the sides and top of the fan back at you. It is not that box fan can not move the air it is just that you are trying to move a stream of air 2 feet across against a wall of air the size of the entire city you are in moving in the other direction. It is kind of like trying to use a squirt gun to spray water upstream in a river.
What you want is a controlled way to move the gas cloud;
1) away from where you don't want it
and
2) to a place where if the wind dies down it can settle on to something you wont be handling like a roof top of shingles or a lawn of grass where the next rain will wash it into the soil harmlessly
and
3) you want to use this gas removal system to make sure that the cloud of gas ( which is only about 30 inches from your nose at the most) goes away from your face and pulls fresh air over your shoulder into the area you are breathing from.
I suggest you do this and
I hope some of our learned members will correct me if I get any of this wrong.
A) Read all the ventilation stuff you can find here and anywhere else. It can be a little thick but you only have to learn this stuff once. When you get the ideas down it will be easy to figure out what will work and what wont work and why.
B) Get a n 8 inch ventilation fan that can move at least 650 cubic feet per minute of air and hook it to straight sided duct work.
C) Build a "fume hood" or a "barley box" or use a "large to small duct transition" right in front of the torch flame to capture the gas fumes and route them to the fan.
D) Mount the end of the duct work to a sheet of plywood or 2 inch thick foam and stick the sheet across the door way or a window that is at least 10 feet from where ever the fresh air is going to come in to replace the air that is going to go out the duct work. (If you do this in a door way it would be better to continue the duct work outside for ten feet to keep from contaminating the door frame. Also, if you use a door for this you can take it apart when you are done for the day and not have to block the door way all the time.)
D.2) You could even route the duct work to go outside under the garage door if you make some kind of blocking for the area between the door and the floor that is the same height as the duct work.
Don't use flexible duct work because the ruffles inside slow down the air movement so much that all the "dust" just settles in the duct work and then you wind up with 15 feet of contaminated duct work that no one will take off you hands except for a hazardous waste facility and those are expensive.
Keep the length of ductwork as short as you can and limit the number of bends to 2 each 90 degree bends other wise it slows down the air flow too much.
I am sorry that it just doesn't work inside the garage like it would on a bench in the backyard.
Don't hesitate to ask the questions that will help you understand all of it better.
Oh and Welcome to the Addiction.