Impact assessment of surface ozone exposure on crop yields at three tropical stations over India

Abstract Surface ozone is a damaging pollutant for crops and ecosystems and the ozone-induced crop losses over India remain uncertain and a topic of debate due to lack of sufficient observations and uncertainties involved in the modelled results. In this study we have used the observational data from MAPAN (Modelling Air Pollution And Networking) for the first time to estimate the relative yield losses, crop production losses and economic losses for the two major crops (wheat and rice). The detailed estimation has been done focussing on three individual suburban sites over India (Patiala, Tezpur and Delhi) and compared with other related studies over the Indian region. We have used the concentration-based metric (M7, 7-hour average from 09:00 to 15:59 hours) along with the cumulative ozone exposure indices (AOT40, Accumulated exposure Over a Threshold of 40ppb) and applied the Exposure-Response (E-R) functions for calculation of the crop losses. Our study shows that the yearly crop losses can reach the level of 12.4–40.8% and 2.0–11.1% for the wheat and rice crops respectively at certain places like Patiala over India. The annual economic loss can be as high as 373 million INR (Indian Rupee) and 53.8 million INR for wheat and rice crops respectively even at individual locations over India. Our estimated %RYL (Relative Yield Loss) lies in the range of 0.3+/ 0.6 times of the recent regional model estimates which uses only the AOT40 metric. Region-specific E-R functions based on factors suitable for the Indian region needs to be developed.