Figure 7 is incorrect. Please see the correct Figure 7 here:
In addition, the name of the first author was incorrectly expressed in the Citation. The correct Citation is: Calderòn Guerrero C, Günthardt-Goerg MS, Vollenweider P (2013) Foliar Symptoms Triggered by Ozone Stress in Irrigated Holm Oaks from the City of Madrid, Spain. PLoS ONE 8(7): e69171. doi:10.1371/journal.pone.0069171.
Footnotes
Competing Interests: No competing interests declared.

