The report from the Royal Society said background concentrations of ozone have increased in parts of the Northern Hemisphere by 6 percent each decade since the 1980s.

Researchers said ozone, which is formed when sunlight reacts with pollutants and naturally occurring chemicals in the air, damages crops such as wheat, rice and soybeans. The report said crop losses due to ground level ozone are likely to increase over the next two to three decades.

"Until we have a globally coordinated approach that addresses the international nature of the problem, national and even regional level controls are unlikely to deliver the kind of reductions that are necessary to protect human health and the environment," David Fowler, chair of the Royal Society's ground level ozone working group, said Monday in a release.

Studies suggest ozone-related crop yield losses in India in 2000 were at least 13 percent for wheat, 6 percent for rice and 19 percent for soybeans, the report said.