Carbon Monoxide

WHAT IS IT?

Carbon monoxide is a product of incomplete combustion of hydrocarbons. Common sources are automotive exhausts, furnaces, some home heating, and exposure to methylene chloride fumes, for example from paint strippers (methylene chloride metabolises to carbon monoxide in the body). Carbon monoxide is odourless, colourless and tasteless.

WHY IS IT A PROBLEM?

The haemoglobin in the red blood cells normally combines with oxygen, O2, transports it to where it is needed, then releases it. CO competes with O2 for the haemoglobin binding site and thus blocks its O2 carrying capacity. The affinity of binding for CO is more than 200 times greater than O2, so that once CO has bound to a heame group it may prevent that heame group from transporting O2 for as much as several hours. Binding of CO to one of the four sites of haemoglobin also abolishes the co-operativity of O2 binding at the other sites. This makes unloading O2 more difficult. Because of the very high affinity for haemoglobin, very low levels of CO in environmental air can result in formation of significant amounts of bound CO-haemoglobin and a decrease in the blood’s O2 carrying capacity.

Symptoms of CO poisoning typically include headache, nausea, vomiting, weakness, collapse, coma and death. In some cases there are few warning signs preceding collapse. Once collapse occurs treatment is difficult and about 30% unsuccessful.

TOXIC FRIENDS

CO can come alone or with other toxic components, depending on the source. Incomplete combustion from for example motor cars or cigarette smoke, has many other toxic components along with the carbon monoxide. Some are irritants, others are very toxic. Since some of these compounds can be difficult or expensive to test for, eg nicotine in cigarette smoke, carbon monoxide can be used as a marker for these other compounds. Published Guidelines for acceptable CO levels are generally based on the assumption that CO is the only contaminant. In practice frequently a host of contaminants are present. This should be borne in mind when reviewing the monitoring results.

WHAT CAN BE DONE ?

CO levels can be measured using an electrochemical sensor. Spot checks are OK for some applications but in most situations, eg car parks, CO levels can fluctuate widely. Spot tests can be misleading. Continuous monitoring with data logging over an extended period, eg one shift is far more reliable.

Once the CO profile is measured an appropriate strategy can be developed to ensure a safe and healthy environment.

CONTACT NEW ENVIRONMENT WHO CAN TELL YOU IF A CARBON MONOXIDE PROBLEM EXISTS, AND IF THERE IS A PROBLEM WHAT IT IS, AND WHAT CAN BE DONE ABOUT IT.