Why Are Some Cities Worse for Allergies Than Others?
“The fundamental issue with cities is the type of plant or grasses, trees or weeds that grow in the area,” says Daniel Waggoner, MD, an allergist in Mystic, Conn., who is not affiliated with the list creation but is familiar with it.
Cities with an exceptionally high concentration of trees, grass, or weeds may have more pollen in the air, he says. Local environmental factors such as wind, humidity, typical temperatures — and air pollution — also play a role in allergies, notes Miguel Wolbert, MD, an allergist in Evansville, Ind. and a certified pollen counter.
What if you don’t live in a major city? How can you tell if your region is especially bad for allergies? Here’s what the experts have to say.
Allergy Risks by Geography
Near River Basins
“If you are around certain river basins, such as in Ohio or Mississippi, higher pollen counts occur due to high humidity levels,” says Wolbert. Pollen thrives in high humidity, he says.
In the middle of Mississippi, everything sits, Wolbert says, so pollen is likely to be worse.
Plants around river basins vary in different parts of the country. For instance, in the lower Mississippi, ragweed and chenopods thrive, Wolbert says.
In the Mountains
In the mountains, there are fewer plants, Wolbert says, perhaps explaining why some mountainous states are absent from the list. “The higher the mountains, the fewer the plants,” Wolbert says, resulting in less pollen overall.
And pollen from evergreens is typically heavy pollen, so it falls to the ground relatively quickly, he says. It poses less of an allergy problem simply because it is airborne for a shorter time.
Near the Coast
While some seaside towns made the list, in general a sea breeze helps reduce allergens, Leftwich says. The closer to the sea the better. “If you can afford to live in that first quarter mile from the beach, it’s great. Pollens are not so much a problem there.”
In coastal areas that are densely populated, however, the pollution can make allergies worse despite the sea breeze, Wolbert says. One exception: In Miami, he says the sea breeze is strong enough to reduce pollen-triggered allergies, despite the population.
Allergy Risks by Region of the U.S.
It’s difficult to pick out one region of the country as “better” or “worse” for allergies, according to the experts. Why? Even within a region the trees, grasses, and weeds that typically provoke allergies can differ.
People’s sensitivities are very different, too. For example, one person may be allergic to tree pollen. Another person may be allergic to grass pollen. Your allergies react to the plants that surround you, no matter the region of the country. Nonetheless, here are allergy triggers to look for, region by region.
The Midwest
The Midwest, known for its ragweed pollen, has several cities on the list including Dayton, Ohio, and St. Louis. Some experts believe global warming is making the ragweed season longer, Wolbert says, so pollen may just get worse.
”Ragweed thrives with higher carbon dioxide,” he says. So the more air pollution, the hardier ragweed becomes. “I think ragweed will continue to worsen every year,” he says.
Global climate change also appears to increase ragweed – and allergic disease – according to recent studies in medical journals, including the Journal of Allergy and Clinical Immunology.
In the Midwest — Illinois, Indiana, Ohio, Minnesota, Wisconsin, Michigan, Iowa, Missouri — tree pollen season is roughly March to June. Trees that typically trigger allergies include elder, alder, birch, oak, elm, and hickory, Wolbert says.
Overlapping the tree pollen season, grasses start to pollinate in the summer, Wolbert says. Grasses that can provoke allergy symptoms include Bermuda, Timothy, fescue, rye, and orchard grass.
Weeds pollinate in the fall, says Wolbert. “Weed season is pretty uniform,” he says. The Midwestern states are known for lamb’s quarter weed, pigweed, Russian thistle, and others.
The West
In Washington, Oregon, and California, tree pollination is usually in full swing from February to June. Trees that are native cause the most allergy problems, says Richard W. Honsinger, MD, an allergist in Los Alamos, N.M., and a clinical professor of medicine at the University of New Mexico School of Medicine.
For instance, in the Pacific Northwest, pollen from the native alder and birch trees can make people with allergies miserable, he says.
In California, oak and walnut trees can be problematic for those with allergies, he says. Pine trees don’t deserve their bad reputation, he says. “People always think pine pollen causes problems because they see it.” When they park their car under pines in the mountain, he says, the car can be covered with the pollen.
“But pine is a heavy pollen, it falls to the ground,” he says.”It is airborne, but it settles. It doesn’t float in the air as long so it doesn’t provoke as strong an allergy attack.”
In the dryer states of Arizona and New Mexico, trees such as cedar, ash, and oak pollinate from about February to April, Honsinger says.
Grass pollination in the West is high in May and June, Honsinger says. Bermuda grass, orchard, wheat grass, and fescue are common in the West. Honsinger says, “If you are allergic to one grass, you are often allergic to almost all,” with one exception. People allergic to Bermuda grasses are often allergic only to those, he finds.
Weed season in the West can extend from spring or early summer through fall. Among the offenders: plantain weed. Ragweed is not so much a problem in the Pacific Northwest and northern California, but it can be in Arizona and New Mexico. Ragweed can grow throughout the U.S., according to the Asthma and Allergy Foundation of America.
The South
When it comes to allergies, Leftwich says, “Tennessee is where everything comes together,” noting there are several different types of pollen flourishing there. His town, Nashville, Tenn., made No. 47 on the list.
Nashville has plenty of Southern state company on the worst cities for allergies list, and for reasons that make sense, Leftwich says. ”The longer the growing season, the worse it is for allergies,” he says.
A second factor is rainfall. So people with allergies who live in a Southern city with a temperate climate, long growing season, and plenty of rain can expect to sneeze a lot.
In the south, tree pollen season is roughly February through May, with pollens from oak, cedar, and pecan trees the worst allergy triggers. Birch and hickory trees can also provoke allergies, Leftwich says.
“Grasses can be a problem in the South year round,” he says. Commonly planted grasses include fescue, rye, and bluegrass. Never mind the type. Often, someone who is allergic to one of those will be allergic to all, he says.
Weed season kicks in around late summer and continues until a hard freeze, Leftwich says. The biggest culprit: ragweed.
The Northeast
In the Northeast — states such as Maine, New York, Pennsylvania, Delaware, Connecticut, and others — tree pollens begin in February or March, continuing through June or so, says Clifford Bassett, MD, an allergist in New York City. Among the offenders: elm, hazelnut, maple, poplar, hackberry, and red cedar.
In May and June, grass pollens kick up. While some people are only allergic to Bermuda grass, most with allergies are allergic to all grasses.
Weed season begins in August and continues through the fall. Pollens from such weeds as English plantain, lamb’s-quarter, and cocklebur provoke symptoms, Bassett says.
http://www.webmd.com/allergies/allergy-relief-10/worst-allergy-cities?page=1