HSE Advice on Atmospheric CO2 Safety Limits

The UK’s Health & Safety Executive sets the Workplace Exposure Limits (WELs) on a wide range of substances to help protect the health of workers.

The HSE Document EH40/2005 Workplace exposure limits sets the long-term (8 hours) exposure level for CO₂ at 5000 ppm. Symptoms of exposure to higher levels of CO₂ than this can include:

• impaired judgment and decision-making ability on a short-term basis
• headaches
• lethargy
• emotional irritation

Measuring the CO₂ content of the air around the packing line is part of the site trials we carry out for customers, interested in learning more about how they can reduce their CO₂ consumption and increase the efficiency of their packing lines.

When calculating how much gas a customer could save by adding a Dansensor MAP Check 3 inline headspace gas analyser and a Dansensor MAP Mix Provectus gas mixer to their lines, it is not uncommon for us to find the factory atmospheric CO₂ levels close to the legal, advised limit of 5000 ppm.

In extreme cases, we have discovered packing lines with CO2 at more than 22,000 ppm in the atmosphere. That’s off the scale of our detection meter and edging close to levels critical to life.

The Health & Safety Executive has a wide range of publications about CO₂ safety levels , including “Assessment of the major hazard potential of carbon dioxide (CO₂)” by Dr Peter Harper.

In the paper, Dr Harper explains that CO₂ poses a threat to life when it has displaced the oxygen in the air down to dangerously low levels. And while 50% v/v can be an immediate danger to life, evidence shows that CO₂ can create an immediate threat to life at a concentration of only 15% in air.

Inhalation of elevated concentrations of CO₂ can increase the acidity of the blood, triggering adverse effects on the respiratory, cardiovascular and central nervous systems. The impact on an individual depends on the length of time they are exposured and the concentration levels.

Toxicological symptoms range from headaches (in the order of 3% for 1 hour), increased respiratory and heart rate, dizziness, muscle twitching, confusion, unconsciousness, coma and death (in the order of >15% for 1 minute).