Measured Carbon monoxide concentrations in outdoor air.

Crude accidental hourly values of carbon monoxide (CO) at ground level in the outdoor air measured in the National Air Quality Monitoring Network (LML). Carbon monoxide is a colourless and odorless gas. Carbon monoxide reduces the transport capacity of oxygen in the blood. With high levels of carbon monoxide in the blood, there is a risk for older people with heart problems and for pregnant women. The concentration of carbon monoxide (CO) in the Netherlands has been low for years. Only in cities and along busy roads there are increased concentrations. Carbon monoxide is caused by incomplete combustion. Road traffic is therefore an important contribution of carbon monoxide.