Of course, as concentrations fall so effects decrease. It is accepted that these figures are in a sense arbitrary in that they describe increments of effect along a continuum. Such concentrations occur fairly frequently in the UK but the great majority of people will experience no adverse effects at all. It is fair to say that our knowledge of the effects of particulate matter on health is evolving rapidly and this advice and the bands defined above may require revision in the light of new evidence. Carbon monoxide 11.
Carbon monoxide is perhaps the best understood of the pollutants discussed here.
The most significant exposure to carbon monoxide occurs in the general population as a result of cigarette smoking. Carbon monoxide interferes with the transport of oxygen by the blood and at high concentrations produces unconsciousness and death. Some 60 accidental deaths occur in the UK each year as a result of exposure to carbon monoxide indoors. Concentrations of carbon monoxide in the air are related to concentrations of carbon monoxide in the blood in a well understood and predictable way. In describing levels of exposure, it is usual to speak in terms of that percentage of haemoglobin, the essential oxygen-transporting protein of the blood, which is saturated with carbon monoxide.