CO2 and O2 concentrations in integral motorcycle helmets

Area of Science:

• Environmental Health
• Occupational Safety
• Human Physiology

Background:

• Inhaling excess carbon dioxide (CO2) or oxygen-deficient air poses health risks and impairs cognitive function.
• Previous studies from 20 years ago indicated alarmingly high CO2 concentrations for motorcyclists using integral helmets.

Purpose of the Study:

• To re-evaluate current gas concentrations, specifically CO2, inhaled by motorcyclists wearing integral helmets.
• To compare new measurements with historical data and assess potential cognitive impacts.

Main Methods:

• Measurements of average CO2 concentrations near the upper lip were conducted in laboratory and field settings for four participants wearing integral helmets.
• Time-dependent CO2 concentrations were measured via a mouthpiece during mouth-breathing.
• The effect of opening the visor at standstill was also assessed.

Main Results:

• High average CO2 concentrations were confirmed, exceeding 2% when stationary and falling below 1% at speeds of 50 km/h or more.
• Inhaled CO2 levels during mouth-breathing were approximately half the average concentrations, with brief peaks over 4% at breath initiation.
• At 50 km/h, inhaled CO2 levels dropped to approximately 0.2%, similar to non-helmeted individuals in still air. Opening the visor had no significant effect at standstill.

Conclusions:

• Integral helmets can lead to significant CO2 inhalation, particularly at low speeds or standstill.
• The associated oxygen deficiency mirrors CO2 levels, potentially impairing motorcyclist cognitive abilities.
• Findings highlight the need for improved helmet ventilation or rider awareness regarding CO2 exposure risks.