alveoli
The lungs have millions of tiny air sacs called alveoli. If they become damaged the body can never repair or replace them. Once the damage is done, it is that way for life.
4666.6667
150000000 x 50000 = 7500000000000
150000000 x 1000000 = 150,000,000,000,000
1,500,000
780,000,000
5400
150000000
150000000
150,000,000,000 meters.
Distance to the sun.
1.5 × 108