Estimated crop yield losses due to surface ozone exposure and economic damage in India.

In this study, we estimate yield losses and economic damage of two major crops (winter wheat and rabi rice) due to surface ozone (O3) exposure using hourly O3 concentrations for the period 2002-2007 in India. This study estimates crop yield losses according to two indices of O3 exposure: 7-h seasonal daytime (0900-1600 hours) mean measured O3 concentration (M7) and AOT40 (accumulation exposure of O3 concentration over a threshold of 40 parts per billion by volume during daylight hours (0700-1800 hours), established by field studies. Our results indicate that relative yield loss from 5 to 11% (6-30%) for winter wheat and 3-6% (9-16%) for rabi rice using M7 (AOT40) index of the mean total winter wheat 81 million metric tons (Mt) and rabi rice 12 Mt production per year for the period 2002-2007. The estimated mean crop production loss (CPL) for winter wheat are from 9 to 29 Mt, account for economic cost loss was from 1,222 to 4,091 million US$ annually. Similarly, the mean CPL for rabi rice are from 0.64 to 2.1 Mt, worth 86-276 million US$. Our calculated winter wheat and rabi rice losses agree well with previous results, providing the further evidence that large crop yield losses occurring in India due to current O3 concentration and further elevated O3 concentration in future may pose threat to food security.

Air pollution effect of O3 on crop yield in rural India.

Measurement of surface ozone (O(3)) mixing ratio was made from January 2006 to December 2007 in Ahmednagar (19.1°N, 74.8°E, 657 m above sea level), India. The monthly average of daytime maximum of O(3) mixing ratio ranged from 14 to 57 parts per billion by volume (ppbv) with an annual average of about 20 ppbv. The estimated winter wheat and summer crop yield reduction by 10% and 15%, respectively from present O(3) pollution level associated with AOT40 (accumulation exposure of O(3) concentration over a threshold of 40 ppbv) index values 7370-9150 ppbv h in rural areas.

Surface ozone variability over western Maharashtra, India.

We present the simultaneous field measurements of surface ozone (O(3)) made at the five different sites of western Maharashtra, India for the period between 2001 and 2005. Seasonal variation in O(3) shows a pronounced maximum concentration about 40-50 ppbv in the summer and winter season in the urban site and similar concentration of O(3) is also observed in the rural site despite less emission of precursor gases. The increase in O(3) concentration is observed in the sugar factory premises during sugarcane crushing period. Diurnal patterns in O(3) do not show daytime in situ photochemical buildup at high altitude mountain site. The higher O(3) concentration is observed in the morning hours near to the dam than at urban and rural sites. These variations in O(3) indicate that the local pollutants are major contributors to the O(3) concentrations at the urban and rural sites, while regional transport plays a role at high altitude mountains site. Model simulations using a Eulerian photochemical model have also been carried out with the available data. The comparison of model results with observation shows that a diurnal and seasonal pattern is in good agreement.