Carbon monoxide
Air quality CO
Carbon monoxide, CO, is a poisonous, colourless and odourless gas produced by incomplete combustion. Outdoor weather-page values cannot establish whether an indoor space is safe from CO.
When fuel does not burn completely
Burning carbon-containing material can produce carbon monoxide (CO), especially with insufficient oxygen for complete combustion. Engines, fires and heating appliances can be sources. The gas cannot reliably be detected by colour or smell.
Why it is dangerous
CO binds strongly to haemoglobin and interferes with oxygen transport in the blood. High concentrations can be life-threatening. CO and CO₂ are different gases: a carbon dioxide monitor is not a carbon monoxide alarm.
What our outdoor data shows
The model display describes outdoor air over a wider area. It may use µg/m³, while other sources use mg/m³ or ppm. These numbers require conversion before comparison. The averaging period also matters.
A green weather display has not checked the heater
CO can build up in a room, garage or tent independently of the outdoor value. Faulty combustion appliances or a barbecue in an enclosed space can be dangerous sources. This website cannot replace a suitable CO alarm. If an alarm sounds, leave the affected area, warn others and call 112 from outside.