Over the last ten years or so, interest in outdoor ambient air pollution monitoring has tended to move away from carbon monoxide and towards other pollutants such as NOx and particulate matter. This is due to the limited direct health impacts associated with exposure to modest amounts of carbon monoxide. There has also been a gerneral decrease in the ambient concentrations of carbon monoxide measured in recent years as a result of improved vehicle technology. However, carbon monoxide measurements are strongly related to road traffic emissions, and generally highly correlated with NOx. As such, it can been seen as.
