Ragweed is flourishing, sending more pollen into the air and making many people miserable with an allergic condition called hay fever

The World Health Organization says every year hundreds of millions of people are becoming ill with preventable chronic respiratory diseases.  

One of the most common allergies is said to be hay fever, which is caused by contact with ragweed [Botanical name: artemisiifolia]. Scientists now say the increase in ragweed is stimulated by climate change.  VOA's Melinda Smith has more on this condition.