Answer to Question 1
A tenfold increase would make the concentration around 500 mg/m3, very high
(while still only one-third of the maximum levels characteristic of the deadly London smog,
see Fig. 14.4). Particulates have a high toxicity (Table 14.6), so we would expect a large
increase in symptoms reported from susceptible groups as well as long-term damage to
lungs of exposed people who might not exhibit symptoms.
Answer to Question 2
No, we still should be concerned. The sorts of VOCs plants emit (mainly the
compounds terpene and isoprene) can cause the Smokies to smoke, but the amounts are
dependent on conditions. As the book notes, damaged plants emit greater amounts of
VOCs, and the greater the carbon dioxide concentration, the greater the emission of natural
VOCs. Exposure to anthropogenic VOCs can increase releases from natural sources as
well.
Younger trees generally emit more VOCs than older trees, and some species emit much
more than others. Commercial tree plantations in the south are a large source of VOC
emission increase, and selective logging in forests can cause increases in emissions as well.
In addition, the atmospheric lifetimes of natural VOCs is generally short. Many
anthropogenic VOCs persist in the atmosphere and can travel long distances.
Answer to Question 3
Against stiffer actions: the air is much cleaner than it used to be, so action is not
urgent; it increases consumers' costs; these actions interfere with free enterprise; regulation
hampers competitiveness of businesses; regulations impose more of a compliance burden
on smaller firms than larger firms with more resources; regulations disproportionally harm
the rich, who invest in business that employ the poor; regulations disproportionally harm the
poor, who are less able to switch suppliers.
For stiffer actions: people's health is still adversely affected by emissions; people's
property is still damaged by emissions; costs of remediation are much less than cited by
opponents (see, for example the discrepancy between industry estimates of compliance with
the CAAA and the actual costs); trees and wildlife are still adversely affected by emissions;
crop losses are due to emissions.
Polyploidy has been an important factor in the evolution of plants.
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