Like most physicians, Dr. Kristie Ross, a pediatric pulmonologist, monitors her patients' health through vital signs -- a patient's blood pressure and temperature, or maybe their oxygen level or heart rate. But she also keeps an eye on the local weather report.

As co-director of a children's asthma clinic in Cleveland, Ross frets about extreme temperatures, like the days-long heatwave that gripped two-thirds of the country in July. Hot, steamy conditions means air pollution -- car and bus exhaust, smoke from coal-fired power plants -- lingers at ground level, making it harder for her patients to breathe.

"When I see that it's going to go from the 60s and 70s, up to 90s, over the span of a day or two -- that really gets me worried," says Ross, co-director of the Rainbow Asthma Center at University Hospitals Rainbow Babies & Children's Hospital. "It means we're going to be busy."

A recent study by the Asthma and Allergy Foundation of America found that Cleveland is part of an Ohio-based cluster of asthma hotspots, industrial cities with deep pockets of poverty. That fact, coupled with the increasingly apparent effects of climate change -- particularly in urban "heat islands," where temperatures rise up to 17 degrees warmer than surrounding areas -- could mean Ross's workload might increase in the near future.

In its 2019 report on "asthma capitals," the AAFA ranked Cleveland 5th out of 100 U.S. cities with the highest number of residents struggling with asthma. The Rock 'n' Roll Capital of the World came in behind top-ranked Springfield, Massachusetts; Dayton, Ohio; Greensboro, North Carolina; and Philadelphia, according to the AAFA rankings.

Indeed, five of the Buckeye State's 10 largest cities ranked among the AAFA's top 20 asthma capitals, more than any other state in the AAFA rankings, with Dayton placing highest at No. 2. Cleveland anchors what the organization calls its Ohio Valley Asthma Belt, which stretches from Lake Erie to the north, moves south through Akron (14th) to Columbus (16th), nudges west to third-ranked Dayton and down to Cincinnati (18th) before ending in Louisville, Kentucky (7th), just across the Ohio River.

Its twin is the Mid-Atlantic Asthma Belt, which sweeps south from Boston (9th) passes through Springfield and Hartford, Connecticut (13th) through Allentown, Pennsylvania (6th), Philadelphia (4th), Baltimore (19th), Richmond (12th) and a pair of North Carolina cities, Winston-Salem (20th) and Greensboro (3rd).

Together, the two belts are home to most of the more than 26 million asthma sufferers in the U.S., according to the AAFA.

The American Public Health Association defines asthma as "a chronic lung disease that causes inflammation and closing/tightening of the airways," resulting in coughing and breathing difficulty.

Although asthma is found in all populations, "some groups are at higher risk," according to the American Public Health Association. "African Americans are three times more likely than Caucasians to be hospitalized and to die of asthma. Puerto Ricans have the highest rates of asthma attacks and related deaths."

The Asthma and Allergy Foundation of America said it calculated the rankings using population and public-health data on cities' asthma prevalence, the number of asthma-related emergency department visits and deaths linked to the disease.

The rankings, however, also included other factors that can influence asthma outcomes, including household income, access to health insurance, air quality, pollen count, use of asthma medications, anti-smoking laws and access to specialists.

Approximately 7% of all adults and 8% of all children in the U.S. have asthma, according to the Centers for Disease Control and Prevention. But Ross says, "in a lot of Ohio cities, it's up to 14%, and in some urban areas, it's closer to 20%."

AAFA President and CEO Kenneth Mendez says it's logical that the Buckeye State has so many asthma-belt cities in the top 20. Each one, he says, has a number of the risk factors associated with the disease, including "industrialization, (air) pollution and (high) rates of poverty."

A 2017 report from the Ohio Manufacturers Association reflects Ohio's history as a link in the nation's Rust Belt. Goods production is the state's leading economic sector, and it ranks third nationally in the category, behind California and Texas, according to the report.

Examples abound: Akron is home base for Goodyear and other major rubber manufacturers; Honda Motor Co. has an auto plant not far from Columbus, the state capital; and Dayton hosts Wright-Patterson Air Force Base, a massive military installation with two active runways and its own power plant. In its heyday, Cleveland was once an iron and auto manufacturing hub.

Meanwhile, Ohio is ranked third in consumption of coal to produce energy, according to the federal Energy Information Administration; only Indiana and Texas burn more. That's led to Ohio becoming the nation's sixth-highest emitter of carbon dioxide, the gas scientists say is causing climate change.

Perhaps not surprisingly, the state's air quality is near the bottom of state rankings, ahead of mining and petroleum-refining states like Louisiana, Delaware and Utah.

Then there's Ohio's struggles with poverty, arguably one of the most significant factors in asthma rates. Studies suggest that it's not unusual to find poor urban communities near highways or industrial areas, or to see residents in low-income housing developments dealing with mold or vermin -- major triggers for asthma attacks. Those households also typically lack access to quality healthcare and abundant asthma medication.

While the poverty rate in Ohio is around the national average of 14.9%, Cleveland's is an eye-popping 35%, and the other four Ohio Valley Asthma Belt cities aren't faring much better, according to US Census Bureau figures. The poverty rate for Dayton, Columbus and Cincinnati each hovers around 32%, while Akron's is about 24%.

Mendez, Ross and other experts point to efforts to attack the asthma crisis in Ohio, from special clinics for asthmatic children to education and mold-eradication campaigns in public housing. But they also agree that the biggest X factor -- climate change -- may be beyond their control, especially in densely-populated cities already grappling with warmer-than-normal hot spots.

"Climate change leads to higher temperatures and longer, more severe, and more frequent heat waves," according to a fact sheet from the federal Environmental Protection Agency. "Urban areas already suffering from the heat island effect will bear the brunt of these harsher heat events."

"If you want to take a look at what climate change will look like, just go to an urban center," says Mendez. "The warmer temperatures create longer growing seasons. If you put ragweed in a container, and you just pump it full of carbon dioxide, it's like growing ragweed on steroids. The longer that growing season goes into the fall, you're going to have a longer (asthma) season."

Dr. Ankoor Y. Shah, an asthma specialist in Washington, says it isn't just punishing heat and poor air quality that can trigger asthma attacks. Extreme weather -- including mold-inducing floods and bitter-cold air -- is going to be problems if climate change isn't reversed, he says.

"Asthma spikes depend on season," he says, noting that pollen blooms in spring and fall are usually the worst. But "if it's really hot or cold, you're not going to be outside -- you're going to be in the home," and in low-income homes risk factors, from stale air to cigarette smoke, are more prevalent.

"The home might have a lot more triggers than outside," says Shah, medical director for Improving Pediatric Asthma Care in the District of Columbia, known as IMPACT DC. The program treats underserved children with poorly controlled asthma by education and clinical management as well as addressing social and environmental determinants of asthma health.