Doctors at Metropolitan Hospital, at 97th Street and First Avenue, gave the frightened parents a diagnosis more common in New York City than anywhere else in the country: asthma.

Asthma, a chronic lung disease, causes breathing problems that can be fatal, if left untreated. Episodes or attacks of asthma are usually prompted by triggers such as pollution, mold, exposure to pets or pests, cold temperatures, cigarette smoke or viruses. The disease, however, can almost always be controlled by medications taken regularly.

William Cotto, now 11, takes medicine twice a day to control his asthma and leads a reasonably normal life, although he plays cards during gym class, rather than exercising with his classmates. He has five inhalers readily accessible to him at home and school to ward off the onset of an asthma attack. He continues to return to Metropolitan Hospital every three months for allergy shots, but he hasn’t visited its emergency room in years. However, he isn’t the only member of his family coping with asthma – his mother and three of his younger siblings have also been diagnosed with the chronic disease.

“The rate of asthma in New York City is high in general due to poor air quality,” said Dr. Jordan S. Josephson, 49, a specialist in otolaryngology at the Manhattan Eye, Ear and Throat Hospital and author of the recently published “Sinus Relief Now.” Dr. Josephson, an Upper East Side resident, has suffered from allergies and asthma himself since he was a child. Dust, pollen and high levels of car exhaust cause his sinuses to flare up and provoke his asthma.

“People often report that their asthma worsens in the city and clears up outside New York City,” Dr. Josephson said. He added that he has seen worse sinus disease and asthma in his patients since the attacks of 9/11.

New York City has the highest asthma rates in the country. More than one million of its residents, including 300,000 children, have received a diagnosis of asthma during their lifetimes, according to Louise Vetter, co-chair of the New York City Asthma Partnership and chief executive officer of the American Lung Association of the City of New York. In 2006, 150,000 city residents went to a doctor for treatment of asthma symptoms, Vetter said.

Within New York City, the communities that suffer from the highest incidence of asthma are East Harlem, the South Bronx and central Brooklyn, although asthma rates can vary greatly block by block. Residents of highly populated, low income neighborhoods located near heavily trafficked roadways or transportation hubs such as bus depots are particularly vulnerable to the chronic lung disease. Manhattan’s Lower East Side, where many residents live in public housing located close to the FDR Drive and the East River bridges, also reports above average rates of asthma.

Efforts to reduce the prevalence of asthma in the city have made progress over the last dozen years, but residents still experience asthma at rates much higher than the national average. In addition to asthma’s common triggers – allergens, mold, infections and viruses -- Manhattanites face the challenge of the city’s declining air quality.

“In the early 1990s, it was a revolving door for both children and adults with asthma in the emergency room,” said Dr. Sarla Inamdar, chief of pediatrics at Metropolitan Hospital in East Harlem. By the mid-1990s the hospital and its auxiliary had developed a community-based campaign against asthma and a family-centered asthma program that worked in cooperation with city agencies. The result: asthma hospitalizations for children in East Harlem fell from 36.5 to 11.9 per 1,000 children from 1995 to 2005, a decline of 59 percent.

“The nurses here teach you how to live with asthma,” Lourdes Cotto said about her family’s asthma treatment experience through Metropolitan Hospital. The Cottos also receive visits from the city’s department of health to check for asthma triggers in their home and to provide them with hypoallergenic bedding and supplies.

Despite significant improvement, however, East Harlem’s rate of asthma hospitalizations remains more than twice the city’s overall rate of 5.4 per 1,000 children and almost three times the national average of 3.4 asthma hospitalizations per 1,000 children.

“We have a long way to go before we can breathe a sigh of relief about the asthma problem,” said New York State Sen. Bill Perkins, whose district includes Harlem and part of the Upper West Side. He said that asthma rates have fallen over the years due to community-targeted asthma educational campaigns and programs that reduce triggers such as rodent and insect infestations, but Perkins stressed that citywide asthma rates are still unacceptable.

The American Lung Association’s 2007 State of the Air report gave Manhattan a failing grade for its air quality and identified adults and children with asthma as one of the groups most at risk. Maureen Googoo, a Canadian who moved to New York City last fall, had her asthma under control with daily medications; she had not had an asthma attack since 1998. Within one month of moving to the city, however, she experienced a full-blown attack. Her doctor advised her that New York City is one of the worst places for asthmatics to live because the air quality is so poor.

Googoo decided to return to Canada last spring because she felt her life depended on breathing cleaner air, and she currently resides in Nova Scotia. “The only thing that seems to be aggravating my asthma now is the ragweed pollen – and that I can handle,” she wrote in an e-mail.

Earlier this year, Mayor Michael Bloomberg proposed a congestion pricing plan for Manhattan to improve traffic flow, promote public transit and reduce air pollution. The city was recently awarded $345 million from the federal government to implement a pilot congestion pricing program.

Senator Perkins supports a carefully designed congestion pricing plan for the city because he believes it will improve overall air quality and residents’ health, but he opposes a program that will increase traffic congestion and pollution in his northern Manhattan district.

“Pollution from traffic is a trigger for asthma, and reducing the trigger will help,” said Senator Perkins who described himself as a lifelong asthmatic and a marathoner.

Last July, doctors from the Johns Hopkins Bloomberg School of Public Health, New York University, Mount Sinai and the Mailman School of Public Health at Columbia University also urged that the city adopt a congestion pricing plan in Manhattan in order to improve health of its citizens. They recommended that the city strive to reduce vehicle emissions that produce fine particles pollutants, called PM2.5, and ozone -- both triggers that worsen asthma symptoms and lead to increased emergency room visits and hospitalizations for respiratory conditions.

“One of the most important things that a city can do is to use tools like congestion pricing to reduce the levels of traffic pollution that we’re exposed to every day,” said Andrew H. Darrell, Regional Director of Environmental Defense, a nonprofit environmental organization. London’s congestion pricing plan, instituted in 2003, has resulted in reduced traffic, which moves more swiftly, and lower levels of both carbon dioxide and particle pollution.

In its March 2007 report “All Choked Up,” Environmental Defense identifies an elevated health risk zone of 500 to 1,500 feet around congested, highly trafficked roadways. The report warns that children and adults with asthma should avoid playing or living in elevated risk zones.

The city is currently planting oaks, lindens, sweet gum and ash trees wherever possible along streets and highways to improve air quality. “The impact that trees, especially larger trees, can have on pollution mitigation is now being comprehensively proved in studies,” said Bram Gunther, deputy director of forestry and horticulture for the city parks department. The parks department’s Trees for Public Health program focuses on East Harlem to help minimize its high respiratory disease rates, including asthma.

But not all locations where Manhattan traffic clogs – bridge and tunnel entrances or along the FDR Drive or the West Side Highway – can provide a hospitable environment for large trees. Gunther said that trees in those pollution hotspots would act as “living filters,” but the trees themselves might not survive the intense amount of exhaust they would encounter.

Beyond the health issues posed by vehicle emissions, city residents also continue to cope with the aftereffects of 9/11. The fall of the towers created a dust and debris cloud over lower Manhattan that took days to dissipate. The World Trade Center Health Registry, begun in 2003, tracks the physical and mental health of more than 70,000 people affected by the disaster. Survivors who were caught in the dust cloud have reported newly diagnosed asthma at twice the rates of those not caught in the cloud.

Julie Barnes, 47, a psychologist, has lived and worked in downtown Manhattan since 1991, and she volunteered in Red Cross respite stations at Ground Zero after 9/11. About four years ago, she started taking dance classes, but she was bothered by a persistent cough when she exercised. Although she had been treated for allergies for years, the nagging cough was a new, worrying symptom. Her allergist sent her to a pulmonologist who diagnosed asthma.

Almost three years later, medication effectively controls her asthma, enabling her to dance, but if she catches a cold, she can experience breathing problems that last for several weeks. While she said she’s not certain whether there is a connection between 9/11 and her condition, she’s at least pleased to have a diagnosis.

“It was a relief to figure out what was going on,” Barnes said, “because I couldn’t breathe.”