Phoenix, one of thedirtiest cities in the U.S. for particle pollutionaccording tohttp://www.stateoftheair.org/2014/states/arizona/maricopa-04013.html,is also the worst big city in the United States for ragweed allergy sufferers, according to a new study released this week.

The long-awaited report, “Allergies Across America,” is the largest analysis ever of allergy patients in the U.S. In addition to extensive findings regarding the current levels of asthma and allergies, the report identified the worst ragweed cities, based on the percentages of patients who showed sensitization to common ragweed.

The 10 worst cities were (with ragweed sensitization rate):

1. Phoenix (29.3)
2. Las Vegas (25.7)
3. Kansas City (24.1)
4. Riverside-San Bernardino (23.9)
5. Dallas (23.6)
6. Chicago (23.1)
7. Sacramento (22.9)
8. Philadelphia (22.6)
9. Denver (22.3)
10. TIE: Washington D.C., Minneapolis/St. Paul (21.7)

The study found that sensitization to common ragweed grew overall by 15 percent in the last decade.Quest Diagnostics, the sponsor of the study, concluded that climate change plays a role in the increase.

“These findings are consistent with other research suggesting climate change may contribute to an increase in certain environmental allergens, such as ragweed,” the report noted.

Other key findings of the study:

• America’s allergy problem is increasing.
• Men had higher sensitization rates than women.
• Children had higher sensitization rates than adults.
• Peanut sensitization affects 1 in 4 children, and the rate is even higher among children 5 and younger.
• Economically disadvantaged children were 18 percent less likely to be tested by age 5.