Carbon oxide is a colourless odourless gas, slightly lighter than air. It is one of the most wide-spread atmospheric pollutants, which is generated during incomplete burning of carbon-containing matter.
The largest CO source is automobile transport – it generates over 65% of the total emitted quantity for the country.

Impact on human health
Carbon oxide penetrates the human body through respiration. In blood it combines with haemoglobin and forms carboxihaemoglobin, the links of which are 250 times more stable than of oxihaemoglobin.
Its adverse effect results from the disturbance of oxygen transfer to the tissues. Prenatal exposure may cause fetus damage. The health effects of carbon monoxide are due to the formation of carboxihaemoglobin. The formed carboxihaemoglobin may cause tissue hypoxia and disorders of the oxygen-deficiency sensitive organs: heart, brain, blood vessels and form elements. The health risk is evaluated based on the carboxihaemoglobin formed in the organism, which depends on the concentration in the air and the period of exposure. Low concentrations of carboxihaemoglobin (below 10%) may cause symptom intensification with patients, suffering from stenocardia, or neurobehavioral effects.
Levels of 2.5 – 3.0% carboxihaemoglobin, which is equivalent to a 30-minute exposure to 60 mg/m3 or 8-hour exposure to 10 mg/m3, are defined as harmless. Such levels are recommended for public health protection. Patients with cardiovascular diseases are sensitive to high concentrations.

Our legislation sets the LV for carbon oxide content in the atmospheric air as follows Regulation No. 1, State Gazette, issue 14/16.01.2004. Regulation No1 reports p. 36 from Annex No1 of Regulation No. 14, State Gazette No. 88/1997, amended , SG No. 8/2002. - health protection LV, defined as 8-hour average value - 10 mg/m3