Air pollution

AOT40 - Accumulated
ccumulated dose Over
a Threshold
of 40 ppb
The long-term critical level of ozone for beech:
An AOT40 of 10000 ppb.h accumulated over a 6 month growing season and
calculated daylight hours only between April and September.
The critical threshold of 10 ppm.h:
relates to an estimated 10% reduction in growth of young beech trees
exposed to O 3 for 1 and 3 seasons
based on 5 studies of above-ground growth and
based on 3 studies of above ground biomass increment (Fuhrer et al.
1997).
Herschbach 2007