Environmental Stressors
UV, CO₂, heat, cold — four atmospheric loads that degrade performance.
Four instruments for the external loads on a human chassis: UV burn time by skin type, indoor CO₂ vs cognitive performance, WBGT heat-stress index, and required clothing insulation in clo units.
Start here
- Thermal Failure — WBGT — heat-stress threshold decision.
- CO₂ Cognitive Tax — Indoor air and decision-making performance.
Featured tools
UV Exposure Delta · Fitzpatrick MED
Minutes to a Minimum Erythemal Threshold by Fitzpatrick skin type and UV Index. Protected time via SPF.
CO₂ Cognitive Tax
Indoor CO₂ ppm to cognitive decline mapping. 1400 ppm halves strategic decision-making performance.
Thermal Failure · WBGT
Wet-bulb globe temperature — the heat-stress index used by OSHA, ACGIH, and military for work/rest cycle decisions.
Insulation Logic · Clo Units
Required clothing insulation in clo units for air temperature and activity level. Suggested garment stack.
Guides & explainers
- Environmental Stressors GuideEstimate outside loads before they quietly degrade comfort, safety, and performance.
- Indoor CO2 · The Cognitive Tax1400 ppm halves strategic decision-making. Most offices sit at 1200-2500 without mechanical ventilation.
- WBGT · The Heat Stress StandardWet-bulb globe temperature is OSHA, ACGIH, and military doctrine. Wet-bulb 35°C is the absolute human limit.
- Clo Insulation · The Layering Math1 clo ≈ a business suit. Higher activity generates metabolic heat, lowering required insulation.
Related clusters
Frequently asked questions
› Why WBGT instead of heat index? Troubleshooting
WBGT adds radiant load (globe temp), so it handles direct sun. Heat index is dry + humidity only. WBGT is the OSHA and ACGIH standard.
› What is wet-bulb 35°C? Definition
The absolute thermoregulatory limit — evaporation can no longer cool a healthy adult. Fatal within hours regardless of hydration or fitness.