Premises
1) Until 1985, airlines replenish cabin air once every 30 mins
2) since 1985, airlines replenish cabin air once evey hour
3) less frequent cabin air is replenish -> higher level of co2 in the plane
4) high level of co2 -> easier for airborne illness to spread
A) In 1985 there was a loosening of regulations concerning cabin air in commercial airline flights.
- not supported for in the passage
B) People who fly today are more likely to contract airborne illnesses than were people who flew prior to 1985.
- Can we really tell that from the statments? Which premise supports allows you to confidently say "yes, people today are weaker and more prone to airborne illness)
C) Low levels of carbon dioxide in cabin air make it impossible for airborne illnessess to spread.
- can't tell if it becomes impossible
D) In 1980 the rate at which the cabin air was replenished in commerical airlines was sufficent to protect passengers from the effects of carbon dioxide buildup
- again, we don't know from the passage if it's sufficient.
E) In 1980 the level of carbon dioxide in the cabin air on a two-hour commercial airline flight was lower than it is today on a similar flight.
- I go with this. On a 2 hr flight, pre 1985 would see the cabin air replenished 4 times, while post 1985, the cabin air would be replenished just 2 times. Based on the statement, the less frequent cabin air is replenished, the higher the level of of co2 in the plane. So since cabin air is replenished more frequently in 1980 than post 1985, then level of co2 in cabin air in 1980 woul be lower.