Species
Concentration, [X]
ss
Lifetime, t
Nitrogen dioxide, NO
2
250 pptv
(a)
several days
CFC-11, CCl
3
F
280 pptv
65 years
Carbon monoxide, CO
60 ppbv
(b)
several days
(a)
pptv
= parts per trillion by volume
= 1 part in 10
12
(b)
ppbv
= parts per billion by volume
= 1 part in 10
9