Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
The size of the arrows is proportional to the effect of the decrease in oxygen availability, and the figures represent the effect expressed as % change from starting condition (high oxygen).
