As of August 2019 the population of the Earth is 7.7 billion (7.7 x 10°) people. If every person were to count atoms at a rate of 3 atoms per
second (3 atoms/person•sec), how many years would it take for the
collective count to reach 6.0 x 1023 atoms? Assume that there are 365
days in a year.

You exhale co2 which is produced during cellular respiration.  co2 combines with the water in your blood's plasma to make up one half of the body's most important buffer pair, carbonic acid.  the more physical activity you engage in, the more co2 your body is producing.  you can see this by putting some of the cabbage indicator in a glass and then blowing bubbles into it through a straw.  can you see a change in the color of the indicator?