Answer:
First it is important to clarify that your question is incomplete, I do not see the graph you are talking about ..
Although faced with the situation, I took the trouble to investigate in medical pages on this subject, and I conclude that the hypothesis of the doctors is correct ...
Because greater global warming, lower partial pressures of oxygen in the atmosphere (therefore those people who had difficulty breathing will be more affected), greater pollutants in the environment (greater hypersensitivity reactions in allergy sufferers), and the seasons of Heat spread, therefore the pollination processes also and it is there where there is connection with allergies due to ragweed.
Explanation:
Allergies are increased immunological reactions against an antigen, so I added to your question that ambrosia pollen generates more allergies in the respiratory tract than at the cutaneous level, that is why it cooperates with other alterations that environmental contamination generates.
The greater the contamination, the greater the presence of allergies or the longer the allergies will be.
It does so, so you can tell apart the borderlines
