A 36-year-old piano teacher can no longer get through concertos and etudes memorized years ago.
A young mother and office manager finds herself struggling with simple math, and she's forgotten to pick up kids in her carpool.
And a Maryland fire official wakes up exhausted every morning, his head aching. He blames job stress.
All three, it turns out, were the victims of chronic exposures to low levels of carbon monoxide.
Long feared as a quick and stealthy killer, carbon monoxide - in long exposures, and in concentrations once thought too low for concern - is now suspected as the cause of significant, even permanent injury to the brain and heart.
Its victims can be anywhere. In the suburbs of Maryland and across the country, carbon monoxide seeps into new tract homes when commuters warm up their cars in the garage, or is drawn back into the house from the furnace flue when someone flips on a bathroom exhaust fan.
And it is seen as a particular threat in cities like Baltimore, where financially strapped families may rely on a neglected furnace for heat or turn on the gas stove for warmth when the oil tank is drained.
"There is no question there are a sizable number - probably tens of thousands of dwellings - in the city that have potentially dangerous heating systems," says Baltimore Heath Commissioner Peter L. Beilenson.
David G. Penney, a physiologist and carbon monoxide researcher at Wayne State University in Detroit, says, "There probably is no lower limit for the safe effects of carbon monoxide."
Penney and a growing number of researchers suspect that this "occult," or hidden car bon monoxide poisoning, may underlie many complaints of persistent asthma, depression, chronic fatigue and chest pain. Behavioral and mood changes, or learning, memory and concentration problems may also be caused by carbon monoxide. Studies have also linked it to low birth weights and heart failure.
The health threats from these chronic, low-level exposures remain an unsettled area of research. Scientists working on the question agree that more studies are needed. But they're confident they're on to something.
"I feel it is a much larger public health problem than anyone has any concept of at present," says pharmacologist Mary A. McCormick, director of the Connecticut Poison Control Center.
Lloyd Ceccato certainly had no idea his health was at risk from a gas he could neither see nor smell. But he knew something was wrong.
A piano teacher and performer in Waterbury, Conn., Ceccato was proud of his skill with a Rachmaninoff concerto or an Art Tatum jazz run.
But at 36, he found he could no longer get through his favorite Chopin etude. He couldn't remember a phone number long enough to dial it; his head ached, and he felt nauseated and irritable.
It would be five months before he discovered he was being poisoned. Carbon monoxide was seeping into his apartment from a first-floor neighbor's faulty furnace. It was too little to kill him, but enough to snuff out a small part of his brain.
Carbon monoxide (CO) is colorless, odorless, insidious and ubiquitous. It is produced by incomplete combustion, but faulty furnaces and motor vehicles, gas water heaters and dryers aren't the only potential sources we live with.
A gas stove or oven exhausts CO directly into the kitchen, even when it's working properly. So do the compact combustion space heaters now used by 13 million adult Americans, according to a 1997 survey reported by the Centers for Disease Control and Prevention.
And cigarette users inhale smoke containing four times the carbon monoxide found in car exhaust. Smoke from one pack can raise a home's CO concentrations to twice the EPA safety limit for outdoor air.
CO is the largest cause of poisoning in the United States. Each year it kills an average of 544 Americans in accidental exposures, according to the Centers for Disease Control. Another 7,000 to 15,000 people are hospitalized annually.
But experts suspect these acute cases represent a fraction of the true toll.
"There are probably many more exposures than we ever find out about," says Dr. Edward Bessman of Johns Hopkins' Bayview Medical Center. "The typical symptoms would be headache and nausea. So, folks will just chalk it up to some little bug."
When Matt Kelly went to the emergency room of a Baltimore County hospital in 1990 after five or six days of nausea and dizziness, he was diagnosed with an inner-ear infection and given antibiotics.
"A couple of days later, I was throwing up pills left and right. So I went back to the ER, and they gave me more pills," he says.
In fact, the flue in his Baltimore house had caved in, and the gas was backing up into his home.
Kelly wasn't diagnosed correctly until the CO got so bad that paramedics were called to rescue his roommate. Ten years later, at 37, Kelly still complains of memory problems. "I feel like I got a fried brain," he says.
Many people diagnose themselves and get it wrong. Bob Thomas, Maryland's deputy chief state fire marshal, woke up every morning in February exhausted, with a headache.
"I thought it was stress from my job," he says. (Ironically, he was lobbying the General Assembly for a bill to require CO detectors in all new residential construction.)
He suffered for nearly a month before noticing the same symptoms in other family members, and called Baltimore Gas and Electric Co. His furnace was leaking small amounts of CO into his Joppa home.
Thomas reports no long-term health effects, but he has resolved to have his furnace serviced annually. And, he has installed a CO detector. "I am a believer," he says.
Poor at greatest risk
CO exposure is a particular concern in poor, run-down neighborhoods.
St. Ambrose Housing Aid Center in Baltimore examined the furnaces in more than 300 low-income homes as part of the city weatherization program between 1997 and 1999. "I'd say one quarter of the houses with older heating units have some kind of problem," says Robert J. Logston, energy coordinator for Blue Ridge Fuel Co., St. Ambrose's heating contractor.
Collapsed chimneys are common, he says. Old furnaces may also have cracks in their heat exchanger - the device that conducts heat from the burner to the room air. The cracks allow CO to infiltrate the room air as it's being warmed.
Poor families may unknowingly worsen their risk in winter by gathering in the kitchen for warmth when the oil tank runs dry. In a recent federal study, 14.5 percent of the low-income families surveyed in the United States reported using their gas stove or oven for heat.
David Brosch, coordinator for the Baltimore City Weatherization Program, says past efforts to make low-income homes more weather-tight may have inadvertently sealed in CO problems. Now, he says, "We test every single house we go into, even if it has a brand-new furnace."
Last year, the program had to replace about 40 of the 180 furnaces it checked. The rest had to be cleaned and adjusted or repaired.
All fuel-burning appliances produce some CO. Researchers are trying to understand how much is too much.
Very small quantities of carbon monoxide are present naturally in the body. A recent Johns Hopkins University study even identified it as one of several neurotransmitters in the brain - vital chemicals that relay messages from one nerve cell to the next.
But as CO blood levels rise, so does the danger.
Breathed into the lungs, carbon monoxide binds with hemoglobin, the blood protein that carries oxygen throughout the body. Burdened with carbon monoxide, the blood can't hold as much oxygen, and cells become oxygen-starved, or "hypoxic." The heart and brain, where demand for oxygen is high, begin to suffocate.
The poison's toxic effects were once blamed entirely on hypoxia. But researchers are now finding that CO can travel in blood plasma and do cell damage without ever binding to hemoglobin or showing up on blood tests, says Dr. Roy A. M. Myers, retired chief of hyperbaric medicine at the Maryland Shock Trauma Center in Baltimore.
Dr. Stephen Thom of the Uni- versity of Pennsylvania has found that this "free" CO in the bloodstream can trigger cell death in the lining of the heart and blood vessels, leading to atherosclerotic heart disease.
The same process also appears to kill brain cells responsible for memory and learning.
"We can show there is atrophy or shrinkage of these structures," says Brigham Young University neuropsychologist Ramona Hopkins, who has studied people chronically exposed to CO.
Hopkins says that about 25 percent of the people in her studies have cognitive impairments, and 50 percent have behavioral changes - most commonly, depression and anxiety. She believes there is no safe dose of CO.
The federal government has concluded otherwise. The Environmental Protection Agency says 9 parts per million (ppm) or less is permissible for "ambient" (outdoor) air.
The Occupational Safety and Health Administration sets 35 ppm averaged over eight hours as the limit in the workplace. Exposures become "dangerous" when they exceed 100 ppm.
The Consumer Product Safety Commission says alarms listed by the Underwriters Laboratory must ignore CO levels less than 30 ppm. The commission defends the sensitivity rules as good enough.
"I'm not saying there aren't some people with severe heart or lung problems who show effects at lower levels. But for the general public, these alarm points are going to save lives," says commission spokesman Ken Giles.
A growing number of studies suggest that health hazards may result from CO levels below 30 parts per million.
A study of 125,000 births in Los Angeles, published last year in Environmental Health Perspectives, linked low birth weights and ambient CO readings topping 5.5 ppm during the babies' final three months in the womb.
Robert D. Morris, a community health professor at Tufts University in Massachusetts, compared air pollution records with Medicare admissions in seven U.S. cities. In 1995, he reported a correlation between outdoor carbon monoxide levels of 5 to 7 ppm and admissions for heart failure. He says CO could account for up to a million of the 20 million yearly admissions for heart failure.
Federal regulators say the studies suggesting health risks from low levels of carbon monoxide are important, but inconclusive. And researchers acknowledge there are weaknesses in their work.
For example, it is very difficult to get accurate measures of CO exposures because air or blood levels fall as soon as rescuers open a door.
Similarly, when sick patients reach an emergency room it's already too late to measure their prior neurological health.
Discerning chronic CO poisoning in children is especially difficult.
"There are so many confounding variables in intelligence and neurological development and socio-economic class," says Dr. Erica L. Liebelt, a toxicologist at the Johns Hopkins Children's Center. "How do you sort out whether carbon monoxide is responsible?"
The one thing everyone seems to agree on is the value of detectors in preventing death and injury from big doses of carbon monoxide.
Experts recommend models with digital read-outs, and a memory to record intermittent CO spikes that may not trigger an alarm.
They're sold in hardware stores for as little as $40.
When Matt Kelly moved to Florida, he bought one to protect his wife and himself, and their two kids. "It's all-electric down here, but I keep it by the garage so any fumes will be detected," he says.
"All of our patients get them after their experiences ," says CO researcher Ramona Hopkins. "But it's a little late."