Ozone Depletion

Question 1

UVB light causes

Answer 1

DNA damage and skin cancer

Question 2

What are Chlorofluorocarbons?

Answer 2

Used in AC units, fridges and aerosols

• boiling points close enough to ambient temps that gasses can be liquefied with pressure

• Dissolve grease/oils but don’t damage electrical components

• Non flammable and non toxic

Question 3

What wa the Rowland-Molina hypothesis?

Answer 3

CFCs would lead to ozone depletion in stratosphere due to

• persistence of CFCs
—> chemically stable so remain in atmosph. long enough to reach strato

• Dissociation by UV & chlorine release
—> they absorb UV which breaks
chlorine bonds , leave radicles

• Reaction of Cl and O
—> Chlorine reacts with monatomic
oxygen; prevent reactive with 02 to
form 03 (ozone)

Question 4

Evidence for ozone depletion

Answer 4

Satellite surveys
• readings of UV reflected by earth higher than expected
—> ozone levels reduced

Measuring ozone
• Dobson units measure total thickness of all ozone in atmosphere
—> 100 DU = 1mm thick layer
—> Normal levels 300DU; ozone hole
below 220DU

Ground based data collection
• Detevrion of higher levels of UV at ground level shows ozone loss in stratosphere