From the chemical formula:

C6H12O6 → 2 C2H5OH + 2 CO2

sugar yields alcohol plus carbon dioxide

It’s abundantly clear that the process of fermentation produces quantities of CO2, a colourless and odourless gas, which at specific parts per million in room air constitutes a danger to the health and safety of winery personnel. CO2 is twice as heavy as air; therefore, it will sink to the bottom of a room forming potentially deadly pools of gas that will displace oxygen (O2). CO2 has been found to settle in corners of rooms and in areas that are generally undisturbed with low ventilation. The presence of CO2 is not known until symptoms of exposure are experienced, or unless there is a CO2 meter. At peak fermentation the volume of CO2 produced in 24 hours may be 10 to 15 times greater than that which occurs naturally in air (normal room air has 350 ppm). Without adequate ventilation, CO2 can displace oxygen and produce an atmosphere that is both high in CO2 and low in oxygen. With a 1000 L tank in peak fermentation, it was clear to Bee & Thistle that the threshold for safety would be reached quickly.

It’s amazing how much CO2 is produced by the fermentation of sugar into alcohol. CO2 is measured by weight; in fact, it has been stated that when 1 pound (0.45 kg) of CO2 is produced, it creates 8.7 cubic feet (or 0.246 cubic meters) of CO2. So then, that same amount of CO2 will raise the parts per million (ppm) of an average 1,000 cubic foot room by 1,000 ppm.

A few facts to understand:

Carbon dioxide (CO2) is a toxic gas at high concentration.

1,000 ppm: breathable and not dangerous.

5,000 ppm: over an 8 hour shift, this amount of CO2 would be the maximum allowed by OHS (Occupational Health and Safety).

10,000 ppm: breathing rate increases slightly.

30,000 ppm: breathing rate increases to twice the normal rate and a person will likely experience impaired hearing, headache and increased blood pressure.

50,000 ppm+: (STEL) short term exposure limit of greater than 5 minutes; Imminent Danger to Life and Health (IDLH). Breathing increases to approximately four times the normal rate, symptoms of intoxication become evident and slight choking may be felt.

60,000 ppm+: no exposure permitted as doing so could cause immediate loss of consciousness leading to death.

Bee & Thistle Winery has several safeguards in place to monitor and mitigate the hazards of CO2 exposure:

• CO2 monitor between fermenting tanks, nearer the floor level as CO2 is heavier than room air

• Venmar ventilation system, which draws air out of the room and replaces it with warmed outside air, maintaining the CO2 level below 2000 ppm.

• An informational chart outlining the dangers and health effects of CO2.

• Instructional material provided to all personnel as to what circumstances may result in high CO2 levels, how to monitor the CO2 situation, the limitations of mechanical ventilation, and what to do if the readings are high or unobtainable. There is a written policy to follow, which also includes use, care and maintenance of the Venmar and the CO2 monitor, and emergency measures and procedures to follow.

Reference

Ontario Ministry of Labour, Skills and Training Development: OHSA: Alert: Brew-On-Premise Wine Making Establishments
Hazardous Carbon Dioxide Concentrations