CO - Carbon Monoxide. 90% caused by transport. In the home you can't see it, you can't smell it and it
has no taste - but it can give you brain damage or even kill you. Not to be underestimated.
You can ...
Walk more, cycle more, use public transport and go on holiday in the UK (which will help our economy!).
In the home you really need to invest in a Carbon Monoxide detector if you value your life.