Human Air

Overview

Engineering reference data for Human Air in physiology.

Key Formulas

Basal Metabolic Rate

$BMR \propto M^{0.75}$

Kleiber's law — metabolic rate scales with body mass.

Heat Loss

$Q = hA(T_{skin} - T_{air})$

Convective heat loss from body.

Variables

Respiration

An adult at rest breathes 15–18 respirations per minute, exchanging approximately 0.5 liters per breath — roughly 0.5 m³/h. Under heavier exertion, the rate increases 3–6 times (1.5–3 m³/h).

Exhaled Air Composition:

The quantity of carbon dioxide exhaled in 24 hours is approximately 1 kg.

Heat Loss Mechanisms

The human body maintains an internal temperature of 37 °C through the combustion of food. Heat is lost via four primary mechanisms:

Note: Evaporation dominates at high ambient temperatures, while conduction and convection dominate at low ambient temperatures.

Heat Loss Data

The total heat loss from an adult at normal activity is approximately 118 W (2 Met) in a room with temperatures between 19 °C and 34 °C.

Interactive Charts

References

• Original Source