It comes as no surprise that in the performance of their job, firefighters are routinely exposed to hazardous conditions including dangerous breathing environments. Nowhere is this more frequently the case than after a house or other structure fire. One of the more dangerous substances occurring after a fire is carbon monoxide (CO), a common result of combustion. The most dangerous time for a firefighter to encounter CO is during overhaul (which is the clean up stage after a fire). As a molecule, carbon monoxide rises with the heat during an active fire and then settles back to the earth when heat dissipates. Because CO is colorless and odorless, firefighters may believe an environment contains clean air when, in fact, extreme concentrations of CO may be present. High concentrations of CO are dangerous to health, with cumulative effects having the potential to last for years. While early signs may include headache, weakness, dizziness, nausea and vomiting, many people do not exhibit any sign of exposure at all until high levels eventually effect the nervous system.

In the past, firefighters depended on atmospheric CO detectors to help them determine when to remove their breathing apparatus. Until now, there was no way to measure inhaled levels of CO. Because of the high level of risk of CO poisoning encountered by firefighters, the Mountain View Fire Protection District is now carrying pulse CO-oximeters on their trucks in addition to atmospheric CO detectors. They spent the last week training on the new detectors which are now in service on two of their engines.

With the new detectors, once a firefighter leaves a dangerous environment, they are immediately tested for levels of carbon monoxide in their blood.

"In the past there were many times we would have a headache after fighting a structure fire and think nothing more than it was caused by the work involved in fighting the fire," said Jesse Hodgson, spokesman for the Mountain View Fire Protection District.

Now the District's medical division is closely watching for those symptoms. Every fighter is now tested for CO when exiting an environment.

"It's a responsibility we have to take upon ourselves to help ensure our own safety," said Hodgson.

The benefits, however, do not stop there. Hodgson explained that the monitors are not just for firefighters. Firefighters are also using the new detectors on any patient for whom they suspect may have suffered exposure to CO as well. The most common time for a member of the public to encounter CO is when a furnace is malfunctioning or when a fireplace is not venting properly.

The monitor is a handheld device, which has a two-sided probe that attaches to a patients ring finger. At one end of the device are light emitting diodes (LED), that emit light at 8 wavelengths. At the other end, a sensor detects the amount of light absorbed by the vascular tissue between the probes. In this manner, the device detects and measures the amount of both oxygen and carbon monoxide in a patient's blood.

Mountain View, as well as most other emergency providers, has a similar device called a pulse oximeter, which measure the saturation of hemoglobin in the patients' blood. However, because that device cannot tell the difference between carbon monoxide and oxygen, both of which bond to hemoglobin in the blood, the pulse oximetry reading is considered unreliable in these situations. Therefore, the pulse oximeter is not used in cases of suspected CO poisoning.

With the new detector however, the pulse CO-oximeter gives not only the carbon monoxide levels but also an accurate reading of oxygen in the blood by differentiating between oxygen and carbon monoxide. The devices were budgeted for by Mountain View and is the Rad 57 model made by Masimo.

"We've identified a true need for these detectors and are continuously looking at other ways to take necessary steps toward increasing our own and our patient's safety" concluded Hodgson.

Sign and symptoms of possible carbon monoxide poisoning include:

- Headache persisting in a given environment, often going away when the environment is changed, such as leaving the house and going to work or getting groceries.

- Facial flushing

- Fatigue

- Nausea and vomiting

- Confusion and/or disorientation

- In extreme cases, bright red skin or unconsciousness

If you feel you are suffering carbon monoxide poisoning, leave the environment immediately and call 911 from a safe location.