More than 5 million people die every year due to ____.

Scientists have developed ____, that release fewer chemicals into the air.

Electric and hybrid vehicles use the combination of ____ and gasoline.

Electric cars, biofuels, hybrid cars, carpooling, biking, walking, not using fossil fuels, using solar, wind hydroelectric and geothermal energy.

____ rays cause sunburn.

The ____ layer is situated about 15 to 30 km above the Earth's surface.

Ozone layer works like a ____ to protect living things from UV rays.

An ozone molecule has ____ oxygen atoms.

When sunlight hits the ozone molecule, it absorbs UV rays and splits into one oxygen atom and one oxygen gas molecule. That oxygen atom combines with ____ again to form an ozone molecule.

In ____, scientists found a severe depletion in the ozone layer.

The "ozone hole" is on the ____ region.

The main cause of the ozone hole is ____.