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Ozone emission
Ozone is the by-product of the electrophotographic process,
and is generated by the corona wires which place
charges onto photoconductive materials. Therefore the
ozone emission is determined by the amount of voltage over
the corona wires. Ozone trapped inside the toner cartridge
can destroy the charge generation and transfer layers, as
well as the polymeric coating on the toner drum surface. The
chemicals which make up these photoactive layers are all
susceptible to ozone. Ozone can cause eye, nose, throat, and
lung irritation. It can also cause headaches and a dryness of
the eyes, nose, and throat. Various regulatory agencies and
standard setting organizations—such as OSHA, ACGIH,
the Health and Safety Executive in UK, and Canadian Federal
Government—have established limits for the amount
of ozone to which employees may be exposed. The most
current recommended standard is the ACGIH Threshold
Limit Value (TLV), which is based on experimental data
(human and animal) and industrial experience.
VOCs emission
VOC emissions from laser printers were higher as a result
of emission from toners by the heat generated from the
machine during the operation process. Ink-jet printers di>er
somewhat in how the toner is delivered in that a photoconductive
drum is not necessary. In ink-jet printers, the toner
is sprayed towards the paper; in bubble jet printers, a bubble
of toner is formed and then “bursts” towards the paper. This
process is carried out line by line rather than by creating a
photoprocessed image of the whole page.
PM10 (particles with diameter less than 10 _m)
Emissions
The toners used in laser printers contain a wide variety
of chemicals in addition to Dne, black carbon particles or
dyes and pigments for color toners. A study (Schnell et al.
[7]) found the concentration of black carbon aerosol produced
by a photocopier occasionally raised room levels to
the 1 _g=m3 level. This is equivalent to black carbon levels
observed in urban areas under moderate vehicle tra*c.
The concentration of Dnely dispersed, charged black carbon
aerosol is reduced upon cessation of photocopying. The potential
for particulates indoor air emissions is expected to
increase over time between maintenance cycles. Typically, about 75% of the toner is transferred to the photoconductive
drum. Toner particles that do not adhere to the drum
become available for emission to the indoor air. The size of
individual particles in=uences the degree to which they can
be inhaled and the types of e>ects they can cause.
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