by Stan Wolfersberger

Many of the books on glass beads mention the necessity of ventilating your studio. Recent measurements made by me underscore this need. Using detector tubes, I measured levels of a number of gases while my wife made beads with a minor bench burner. The results suggest that NOx, rather than carbon monoxide, may be one of the chief hazards you face in your studio.

What is NOx? This is a shorthand notation for the mixture of nitrogen oxides, which are generated from many types of combustion. The level of NOx depends on many aspects of the combustion process, such as the fuel and oxygen ratio, temperature, etc. NOx is a known respiratory irritant. Propane-oxygen torches attain fairly high temperatures, yet the fact that oxygen is used rather than air for combustion would normally lead one to believe that NOx would not be emitted at high levels.

Part of my job involves performing air sampling and analysis to measure employee exposure to chemicals and irritants. Detector tubes are a fairly inexpensive means to obtain quick, reasonably reliable measures of many substances. Using a small, hand-operated pump, air is pulled through a tube, which is coated with a material that reacts with the substance of interest. A colored stain is formed that is proportional to the amount of the substance present in air. Different tubes are available for many substances.

While Pamela made beads, I used detector tubes to measure the levels of carbon monoxide, carbon dioxide, and NOx in the room. Carbon monoxide was not detected under any condition. Carbon dioxide, while elevated a bit from ambient levels, was not at levels that would cause concern. However, NOx levels exceeded 15 parts per million in air (PPM) on numerous occasions. Even with considerable ventilation, NOx was ALWAYS at levels above 1 PPM.

What does this mean for you? Pamela's current studio is our spare bedroom, which has a single door and window. I have experimented with a variety of fan placements, and so far, I have not found a combination that effectively eliminates the NOx. Unfortunately, complaints of "that fan is blowing my flame" mean that you may be settling for less ventilation than is needed to remove emissions from your torch. We have purchased an overhead fan (like the ones required in bathrooms in new construction) to try and remove more air without disturbing the flame significantly. We'll let you know how this works out.

I'll continue to research this. I discussed what I found with the NIOSH folks who were at Corning. However, they did not bring the equipment to do NOx testing while at Corning, so don't expect any revelations from them short- term. It would be very desirable to get data on other equipment (different torch models, fuels, etc.) to see if this problem is equally severe for all glass bead makers. I hesitate to make broad statements based on measurements from a single torch set-up, but the levels of NOx I found WERE SO SURPRISING that caution is in order. If your family, friends, etc. come into your studio and remark on the odor, this is an indication your ventilation is probably not adequate.