Has there ever been an incident in the U.S. where because of high gas prices people have driven their cars a lot less than usual for, say, many months, and after appropriate measurements it was determined that the ozone layer had less observable properties that might be considered 'damage'? If so, would it show if everyone switched to electric cars or some ‘gas alternative’ this could slowly 'repair' our atmosphere?

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    $\begingroup$ Most car exhaust do not affect the ozone layer, the gases and particulate matter contribute more to the Greenhouse Effect and chemical pollution events. $\endgroup$ – user889 Mar 16 '15 at 4:22
  • $\begingroup$ I asked if the event I described ever happened in real life. Not what might happen if gas powered cars were 'stopped' $\endgroup$ – 201044 Mar 16 '15 at 4:28
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    $\begingroup$ @SabreTooth Not quite a duplicate, since this question is specifically asking about the ozone layer. This probably demonstrates some confusion between ozone depletion and the greenhouse effect, but I think it's worth answering: it's a good opportunity to clear up a common misconception. I've cleaned the question up a bit, and attempted an answer. $\endgroup$ – Pont Mar 16 '15 at 9:52
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    $\begingroup$ @Pont - excellent points, especially about the opportunity to clear up a misconception - close vote retracted and I have upvoted your answer - nicely done! $\endgroup$ – user889 Mar 16 '15 at 9:54
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    $\begingroup$ I doubt that there has ever been a global reduction in car use. (I realise that the question asked about the US, but ozone depletion is a global problem) $\endgroup$ – Semidiurnal Simon Sep 26 '15 at 6:06

The sequence of events you describe has never happened, for several reasons.

  1. As Sabre Tooth mentions in the comments, vehicle emissions have a negligible effect on stratospheric ozone. (Note that while vehicle emissions can lead to ozone production at ground level, the ozone layer is several kilometres above the Earth's surface and isn't really affected by variation in ground-level ozone. The EPA has published a guide entitled Ozone: good up high, bad nearby which explains the distinction in more detail.)

  2. Even the most dramatic attempt to reduce driving in the USA, the National Maximum Speed Law of 1974, only produced a 1% (or less) reduction in fuel consumption; we can assume that reductions in emissions would have been of similar magnitude.

  3. Even in 1974, there were a lot of vehicles outside the USA, diluting the global impact of any changes in driving habits within the USA.

However, to answer a slightly broader question, it does seem that the ozone layer is capable of repairing itself when emissions of ozone-depleting substances are reduced. The Montreal protocol was enacted in 1989:

The Montreal Protocol on Substances that Deplete the Ozone Layer was designed to reduce the production and consumption of ozone depleting substances in order to reduce their abundance in the atmosphere, and thereby protect the earth's fragile ozone Layer. The original Montreal Protocol was agreed on 16 September 1987 and entered into force on 1 January 1989.

A report released in 2014 by the World Meteorological Organization concluded:

Actions taken under the Montreal Protocol have led to decreases in the atmospheric abundance of controlled ozone-depleting substances (ODSs), and are enabling the return of the ozone layer toward 1980 levels.

They estimate that total recovery will occur "before midcentury in midlatitudes and the Arctic, and somewhat later for the Antarctic ozone hole".

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    $\begingroup$ Indeed the ozone layer is capable of "repairing itself" — but not on the timescale of a year or less. $\endgroup$ – gerrit Mar 16 '15 at 16:04
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    $\begingroup$ might be worth mentioning the location of "stratospheric ozone" (e.g. ~20 km above us) as opposed to "ground-level ozone" which does indeed get influenced daily by traffic... I only say this because this answer was offered to clear misconceptions. Also see related: earthscience.stackexchange.com/questions/1037/… and earthscience.stackexchange.com/questions/2126/… $\endgroup$ – f.thorpe Mar 16 '15 at 18:02
  • $\begingroup$ @farrenthorpe Thanks, good point. I've expanded my answer to touch on stratospheric vs. tropospheric ozone. $\endgroup$ – Pont Mar 16 '15 at 18:31
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    $\begingroup$ @201044 Remember that many newspaper reporters lack scientific training, and that the mass media is replete with stories which misinterpret, distort, or outright ignore scientific evidence. If the article in question is generally accessible online, and if you're able to find it again, you are welcome to post a question asking for a scientific evaluation of its plausibility and accuracy. In the meantime, I have answered the question you actually asked; nobody can write a reasonable critique of an article they've never read :-). $\endgroup$ – Pont Mar 17 '15 at 16:58
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    $\begingroup$ ozone layer depletion is primarily due to CFCs, which are not part of car exhaust. Stratospheric aircraft can also cause destruction of the ozone layer, but that is rather short-lived. $\endgroup$ – f.thorpe Apr 28 '17 at 6:22

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