A Warning:
Working glass is inherently dangerous, involving heavy materials that can be razor sharp, so hot that damage can be done before feeling occurs, with chemicals immediately poisonous, dusts that can damage the lungs, and heat sources that can wreck the eyes. Understand the safe practices required and use them to blow beautiful glass.

Chemical Risks
The silicon in colored glass is irrelevant. The chemicals used to make colored glass or to take the color out of batch are far more dangerous than the silicon. Many glass colors contain lead oxide as it expands the range of coefficients of glass that the color will work. Colors like red or orange are made with cadmium in some cases, a heavy metal poison.

The silicon in glass batch (the sand based powder melted to make glass) is dangerous to the lungs and thus it is advised that a respirator be worn when charging a furnace and an effort be made to avoid scattering the stuff around the studio. Most batch contains antimony oxide, arsenic oxide, or some other chemical to react with chemicals that cause color so the glass is clear or "white" metal and these are far more dangerous, short term, than silicosis.

When glass is ground to change its shape or even out a base (cold worked), both the silicon and the heavy metals may be released. Since water is required when cold working glass to keep it from heating and cracking, normally the dust is never in the air, but is carried off in the water and collected as sludge in whatever trap method is used.

Be careful when sweeping or working with glass powder to avoid creating (and breathing) dust.

Eye Protection
Every glass worker should have several levels of eye protection: at a very minimum, break resistant glasses to save the eyes from glass fragments. Furnace workers, according to tests, should be using at least a #3 and preferably a #4 welders shade to observe the furnace and gloryhole. I do this with a relatively low cost ($25) plastic shield on a Jackson 170-S (not the newer 170SB) head band with Glendale Irex (Blue Diamond) 862 shield stocked in #5. The full face shield is also nice in holding off the heat, but I got the idea from a couple in Michigan who cut off the lower half of the shield so they don't have to raise it to blow. I have become adept at raising/lowering the shield quickly.

Glasses commonly used for lampworking are referred to as didymium glasses. This material specifically blocks the yellow sodium flare that blocks viewing the glass in the flame. It does not, in and of itself, block UV or IR, and must be part of shading or other design factors to produce full protection.

Some workers wear welding clip-ons or use a flat piece of welding glass in a frame at the yoke to look through. According to tests, UV is not a problem, IR is too high and protective choices should be made. Many glassworkers use sunglasses or nothing, for better or worse. If your eyes show signs of drying or pain or after effect images, you should be using more protection than you are. Cataracts from IR were found to be a problem at the end of the manual glassblowing of bottles (1870-1890's) once people lived longer due to better health and more obscure problems could come to the surface.

Pay extra attention to cold pipes and punties; glass on the end of these can explode unexpectedly and reheating a cold pipe in the gloryhole can send sharp fragments of glass flying in all directions.

Clothing
It is recommended that glassblowers wear cotton or wool clothing rather than nylon or polyester. Part of the reason is the way that natural fibers hold sweat. But nylon can melt in the heat and if it sticks to the skin is very painful. Many glassblowers work in short sleeves and short pants and pull on a cotton sock with the toe cut out to protect the arm when working bigger pieces. Long sleeved cotton tee's and blue jeans are recommended as good year-round glassblowing wardrobe.

Closed-toe shoes are a requirement to work in the hot shop and metal belt buckles, watches and jewelry are also a risk since they can be inadvertantly heated and can cause burns.

Heat
Heat is different from burns in that heat is an overall effect on the body, while burns (normally) effect a small part of the body. Depending on how a glassworker works, the heat exposure of the body can be very high. Hydration is very important particularly in the summer.

Burns
Most of the more serious burns in the hot shop result picking a pipe or punty from the wrong end [mistaking the dark heat damaged end for the dark rubber handle] or from rolling a pipe and hitting a leg while sitting working. Mild burns from cooling hot glass on the floor, etc., occur also. Always assume that anything metal in the hot shop that could be hot is hot. Metal surfaces have a nasty habit of absorbing and holding heat for a very long time.

Please understand that most glassblowers experience first degree burns frequently, either from working large glass or pausing too long at the furnace or gloryhole.

First Degree - Reddening of the skin with a continuing burning sensation - heavy sunburn
Second Degree - Small to large blisters - damage to surface of skin.
Third Degree - Blackening/charring/cooking of skin - damage to flesh under skin - shock likely.

A serious burn should be plunged/soaked in cold water (not ice) as soon as possible (if the skin is not broken, any water may be ok), to drop the body temperature, then treated medically as needed.

Cuts
Cold glass has sharp edges. At a minimum, inexpensive leather gloves should be kept on hand. Long cuff padded welding gloves cost under $10, eventually getting stiff if heated a bunch. There are gloves on the market with rubber dots on the surface that help grip glass and keep it from slipping. There are also gloves that have Kevlar or other tough fibers to resist cutting through to the hands.

Always be cautious handling un-annealed glass. It can literally explode without any provocation.