Very little light filters through the canopy of leaves and branches in a rain forest to reach ground level—or close to the ground—and at those levels the yellow-to-green wavelengths predominate.

Her monitor has shown that air pollution levels are higher closer to ground level, which has helped highlight concerns that babies and young kids may be at higher risk of developing lung problems.

The English youngster noticed that pollution levels are around two-thirds higher close to the ground than they are in the air at the height where they are recorded by the agency.