No. 104 - Miljøstyrelsen

3 Release of mercury from broken
lamps
This chapter describes information found in various literature regarding
release of mercury when compact/straight fluorescent lamps break.
Quantities of mercury released when a lamp breaks depend on the quantity of
mercury in the lamp, the form of the mercury (i.e. the mercury compound,
unbound/bound to the material in the lamp and casing in some cases) and
other factors such as room temperature (Aucott et al., 2003). The form of
mercury also depends on age and use pattern of the lamp (Aucott et al.,
2003). These factors are described in more detail below.
3.1 Mercury compounds and quantities
Aucott et al. (2003) states based on information from industry that a compact
fluorescent lamp generally contains less than 0.02 mg of vapour-phase
mercury at room temperature (temperature of lamp when not in use). In
addition, around 0.1 mg of mercury is bound as solid mercury compounds
such as HgO.
At an operating temperature of around 40° C the share of vapour-phase
mercury increases, but according to industry quantities do not exceed 0.05
mg. According to another report industry states that only 0.5 % of mercury is
in vapour-phase when the lamp is on and 0.3 % is in vapour-phase when the
lamp is off. This corresponds to 0.025 mg and 0.015 mg of mercury
respectively for a lamp with a total content of 5 mg of mercury (NEMA,
2000).
Jang et al. (2005) states that for new straight fluorescent lamps around 0.17 %
of metallic mercury is in vapour-phase while for used straight fluorescent
lamps this amounts to 0.04 %. This corresponds to 0.009 mg and 0.002 mg of
mercury respectively for a straight fluorescent lamp with a total content of 5
mg of mercury.
One manufacturer states that mercury is only in vapour-phase when the lamp
is on. When off, it is bound to, for instance, the phosphor coating on the inner
side of the glass (Manufacturer C). This, however, is not in line with
information from industry stated above from Aucott et al. (2003). Another
manufacturer states that mercury vapour is not released from the added
amalgam at room temperature (Manufacturer G). Manufacturer D states that
when the lamp is on the major part of mercury is in metallic form regardless
of the compound added.
According to Truesdale et al. (1992) mercury is probably also found in metal
form in used compact/straight fluorescent lamps, since the inactive
atmosphere in the lamp should prevent significant oxidation of the mercury.
Due to repeated evaporation and condensation during use it seems probable
that the mercury is more evenly distributed at the end of the lifetime of the
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