Nothing to sneeze at: Is your city at high risk for allergies and ozone?

Richmond, Va., was named the USA's "sneeziest, wheeziest" city, according to a report out this week from the Natural Resources Defense Council, an environmental advocacy group.

The report details the top 35 U.S. cities most vulnerable to the combination of pollen and ozone pollution and warns that climate change is leading to worsening levels of allergy and asthma.

"Americans deserve to breathe clean air, but today millions of us are sneezing and wheezing from allergies and asthma worsened by climate change-fueled ragweed pollen and ozone smog pollution," said Juan Declet-Barreto, the lead author of the report, which did not appear in a peer-reviewed journal.

In all, 109 million Americans are at risk of the potent double-whammy of bad ozone and high pollen counts, the report said.

The report, "Sneezing and Wheezing: How Climate Change Could Increase Ragweed Allergies, Air Pollution and Asthma," is among the first to warn about this combination of pollen and ozone and its relation to climate change.

Nationally, the most vulnerable regions are the Los Angeles Basin, the St. Louis area, the Great Lakes Region, the Mid-Atlantic and the Northeast, the NRDC report shows.

Richmond tops the list partly due to its being on the top of the Asthma and Allergy Foundation of America's list of "allergy capitals" for two straight years.

"Scientific studies have also shown that our changing climate could favor the formation of more ozone smog in some areas and increase the production of allergenic pollen such as that released by the ragweed plant, the principal source of pollen associated with allergic rhinitis," the report said.

The National Climate Assessment, a federal report released last year, confirms what was in the NRDC report, warning that both ozone levels and allergens would likely worsen due to climate change.

"This is bad news for allergy sufferers and asthmatics because both ragweed pollen and high levels of ozone smog can trigger asthma attacks and worsen allergic symptoms in adults and children," the NRDC report said.

The environmental group recommends that the EPA enact stronger regulations on carbon emissions, tighten ozone standards and increase the collection and dissemenation of data about ozone and pollen levels.

The top 10 "sneeziest and wheeziest" cities are:

1. Richmond

2. Memphis

3. Oklahoma City

4. Philadelphia

5. Chattanooga, Tenn.

6. Chicago

7. Detroit

8. New Haven, Conn.

9. Allentown, Pa.

10. Atlanta