I think the allergy problem is contributed to by factors such as tightly sealed homes and indoor air pollution, mold, reliance on medications to suppress the body's natural adaptive functions, environmental and dietary chemicals that affect our body chemistry, and other contributing factors. Native animals don't seem to suffer the same ill effects we do when their environment is altered.
This may be the case. But it can't refute the fact that higher CO2s help plant life, like trees, to produce more pollen. It's a scientifically proven fact.
