PINE trees might be churning out as much nitrogen oxide pollution as cars and factories, instead of absorbing it.
When an international team led by Pertti Hari of the University of Helsinki exposed Scots pine shoots to solar ultraviolet light, they found the plants gave off the gas, which is blamed for creating smog (Nature, vol 422, p134).
The shoots start producing nitrogen oxides whenever the concentration of the gas in the air falls below about 1 part per billion, say the researchers. But they don’t know yet whether the pines make the oxides, or whether the sunlight merely…
