Carbon Monoxide Poisonings Associated with Snow-Obstructed Vehicle Exhaust Systems -- Philadelphia and New York City, January 1996
On January 9, 1996, CDC was notified about carbon monoxide
(CO)-related morbidity and mortality associated with the blizzard
in the northeastern United States. Most of these poisonings
occurred among children and elderly persons and resulted from
exposures in idling automobiles with exhaust pipes blocked by snow.
This report summarizes three cases of CO poisoning reported to
Philadelphia's Poison Control Center on January 8-9, and 22 cases
reported in New York City on January 8-9.
Philadelphia
Case 1. A 4-year-old girl who had accompanied her family while they
were digging their car out of a deep snow embankment became cold;
to warm the child, she was placed in the car with both the engine
and heater running while deep snow surrounded the rear of the
automobile. The child's grandmother and sister also were in the car
but exited the vehicle after a few minutes when the grandmother
became dizzy and lightheaded. The child was believed to be napping
and was allowed to remain in the car for approximately 30 minutes
before she was found to be unconscious and could not be awakened.
On arrival at the Children's Hospital of Philadelphia emergency
department, she was awake but drowsy and complained of a headache.
She initially was treated with 100% oxygen by nonrebreather mask
and soon became alert and oriented; she was then transferred to the
hyperbaric oxygen unit for a standard treatment regimen. She was
discharged on January 9.
Case 2. A 63-year-old man was brought to the Hospital of the
University of Pennsylvania emergency department by paramedics after
being found unconscious in his car with the engine running.
Approximately 1 hour before being found, the patient informed his
wife he was going to test the car to ensure it would run after the
severe storm. He made no attempt to remove any snow surrounding the
car before starting the engine. At the hospital, he was treated
with 100% oxygen and then a standard hyperbaric regimen. Although
his clinical status improved markedly after hyperbaric oxygen
therapy, residual deficits in short-term memory persisted.
Case 3. An 81-year-old man was found unconscious and could not be
awakened in his car in a suburb outside of Philadelphia. The engine
had been running, and the car was surrounded by deep snow. On their
arrival at the site, paramedics declared the man dead. A
qualitative test for carboxyhemoglobin was positive.
New York City
During January 8-9, a total of 21 persons were admitted
directly to the Jacobi Medical Center or transferred from other
hospitals for hyperbaric oxygen therapy because of CO poisoning. In
addition, one fatal case of CO poisoning was reported in which the
victim was not admitted to the hospital. The cause of the CO
poisonings was directly related to exposure to automobile exhaust
from vehicle exhaust systems blocked with snow. The 21 persons
admitted to the hospital were found unconscious inside automobiles
with engines running. Of these blizzard-related cases, eight were
aged less than 16 years and 12 were aged greater than 50 years
(range: 4-81 years). Of the 21 persons, 17 were discharged within
24 hours of admission and four remain hospitalized.
Reported by: F Henretig, MD, Dept of Pediatrics, Univ of
Pennsylvania School of Medicine, F DeRoos, MD, K Hardy, MD,
Hospital of the Univ of Pennsylvania, Philadelphia; D Contostavlos,
MD, Delaware County; R Levenson, MBA, Philadelphia Dept of Health;
J Logue, DrPH, Div of Environmental Health Assessment, Pennsylvania
Dept of Health. M Touger, MD, Jacobi Medical Center/Albert Einstein
College of Medicine, Bronx; BA Mojica, MD, New York City Dept of
Health. Air Pollution and Respiratory Health Br, Div of
Environmental Hazards and Health Effects, National Center for
Environmental Health, CDC.
Editorial Note
Editorial Note: Each year in United States, approximately 500
deaths are attributed to unintentional CO poisoning (1). CO is an
insidious poison that is a naturally occurring byproduct of the
incomplete combustion of carbon-based fuels. Because CO is
colorless, tasteless, odorless, and nonirritating, its presence
usually is not detected. CO is a component of vehicle exhaust, and
CO can seep into the cabin of a vehicle through leaks or cracks in
the floorboard if the exhaust pipe is obstructed. The CO poisonings
described in this report resulted from inhalation of exhaust by
persons sitting in idling automobiles with exhaust pipes obstructed
by snow.
CO poisoning is not easily diagnosed because early symptoms
are nonspecific (e.g., headache, dizziness, weakness, nausea,
visual disturbances, and confusion) (2,3). Consequently, CO
poisoning may be misdiagnosed as influenza or other acute,
self-limited illnesses (4). Three important factors associated with
carboxyhemoglobin levels and symptoms are 1) the concentration of
CO in the environment; 2) the duration of exposure; and 3) the
interval between exposure and clinical assessment. Normal
carboxyhemoglobin concentrations are less than 2% for nonsmokers
and 5%-9% for smokers. Treatment of CO poisoning requires
termination of exposure and initiation of therapy with 100% oxygen;
hyperbaric oxygen therapy has been recommended for patients with
neruologic or cardiac symptoms, pregnant women, and children when
higher cortical function cannot be measured (2,5).
The epidemiology of CO poisonings in the United States is
characterized by seasonal increases during winter months (1) --
particularly because of the risks for exposure to the exhaust from
vehicles and combustion appliances during periods when heating
appliances are in use and ventilation is more likely to be
inadequate (6). The findings in this report also underscore that
heavy snowfalls are associated with particularly hazardous
conditions in areas where vehicles are parked outdoors. Following
heavy snowfalls, the public should be reminded to inspect vehicles
to ensure that exhaust pipes are cleared of snow before engines are
started. Other precautions to prevent CO poisoning include avoiding
running automobile engines in enclosed spaces (e.g., garages),
inspecting furnaces each year, using space heaters only in
well-ventilated rooms, and inspecting exhaust systems of all
combustion appliances that vent to the outside to ensure that vents
have not been damaged or blocked with snow.
References
Cobb N, Etzel RA. Unintentional carbon monoxide-related deaths
in the United States, 1979 through 1988. JAMA 1991;266:659-63.
Meredith T, Vale A. Carbon monoxide poisoning. Br Med J
1988;296:77-8.
Baker MD, Henretig FM, Ludwig S. Carboxyhemoglobin levels in
children with nonspecific flu-like symptoms. J Pediatr
1988;113:501-4.
Viccellio P, ed. Handbook of medical toxicology. Boston: Little,
Brown and Company, 1993.
CDC. Unintentional carbon monoxide poisoning following a winter
storm -- Washington, January 1993. MMWR 1993;42:109-11.
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