Ozone and electronic equipment
15 ppm? Holy Cow! It might not damage electronics, but it will surely damage you. See http://www.ozoneservices.com/articles/007.htm  12 ppm kills guinea pigs in 3 hours. .05 ppm is the upper limit for FDA-approved medical devices, and 0.1 ppm it the health and safety limit.

That said, I'd expect only a long-term degradation in electronics gear. I'd expect bleaching of exposed surfaces, among other things, but only over a span of months.

ETA - Spehro has brought up the problem of ozone attacking rubber, and Brian has extended the concern to speakers. This is a valid concern. Ozone cracking is well-known, and there exist antiozonating agents (and no, I'm not making the word up) which get added to the rubber before it's vulcanized. I'm assuming that any rubber found a piece of electronics equipment would be so protected just on general principles. Well, we all know what happens when you assume, so I may be wrong. See http://en.wikipedia.org/wiki/Ozone_cracking for a discussion of the problem.