Estimate

A randomly chosen dry-air particle is carbon dioxide

Probability:
0.042%
Odds:
1 to 2,380
dBan
−33.8 dBan

By particle count, carbon dioxide molecules make up about 0.042% of the stated dry-air sample.

Calculation

p ≈ 0.000420 by particle count

Assumptions

Under an ideal-gas model, the published dry-air volume fraction equals the particle fraction. The representative value is dated, and atmospheric CO₂ varies with time and place.

Sources

  1. NASA Earth Fact Sheet composition updated 15 November 2024