The present study showed a possibility to use phenotypic and proteomic responses in rice plants as an in vivo biomarker to detect higher concentrations of ambient ozone (O(3)). The investigation was done on two cultivars of Indian rice using open top chambers ventilated with charcoal filtered air, ambient air, ambient air with 10 ppb O(3) exposure and ambient air with 20 ppb O(3) exposure at a rural site of Varanasi, India. Results showed that the magnitude of O(3) induced specific type of foliar injury directly depends on the duration and concentration of O(3) exposure. Even the internal protein profile of injured and normal leaf demonstrated a differential expression, which directly indicates towards the molecular basis of plant's response against O(3).