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Appendix D
OSHA’s Final Ruling on Silica
Background
Earlier this year, OSHA published the final rule to protect
workers from exposure to crystalline silica. Crystalline silica
can be found in Quartz and is a basic component in soil,
sand, granite and other minerals.
The new rule is to protect more than 2 million workers in
the United States that are at risk to silica exposure. The health effects of crystalline silica exposure has
been linked to disabling illnesses, fatalities and has been classified as lung carcinogen. Exposure to silica
can cause silicosis which is disabling if not fatal by causing scar tissue in the lung and reduces the lungs
ability to take in oxygen. High risk workers would include foundry work, stonecutting, rock drilling, quarry
work, tunneling and any occupation, which can chip, cut drill or grind off crystalline silica in to respirable
size fractions.
In order to minimize the health effects of silica OSHA has established new Permissible Exposure Limit
(PEL) over an 8 hour work shift. The new rule reduced the PEL by 50%. The new PEL is 50 ug/m3.
Additionally, OSHA also adopted an action level of 25 ug/m3 which is the same level as the ACGIH TLV for
quartz and cristobalite.
SM-4000: Personal Real-Time Silica Monitor
Cross Calibration
Real Time Nephelometer are calibrated with a standardized Test Dust. Test dust varies, however a
commonly used test dust is the ISO12103-01A2 Fine Test Dust, or
“Arizona Road Dust.” The particle
characteristics and properties of silica vary from the test dust, causing a variance in the instrumentation
response. To compensate for this variance Cross Calibration is required.
Traditional Cross Calibration requires two devices; a Reference Sampler and a Real-Time Nephelometers.
The Reference Sampler is a pump attached to gravimetric filter. The filter is sent to the lab and compared
with the post ex facto real- time readings. The SM-4000 changes the way sampling is performed and
reduces the need for two instruments. The SM-4000 has a far superior design compared with other Real-
Time Personal Samplers.
The SM-4000 offers a miniature optical sensor mounted in the OSHA defined breathing zone. The sensor
is situated between the gravimetric filter and Respirable Cyclone. The SM-4000 is
THE ONLY device on the
market with this unique feature.
HAZ-DUST Model:
SM-4000 Personal
Silica Monitor
Application Note: New Product DOC1216
HAZ-DUST Model:
SM-4000 Personal
Silica Monitor
Application Note: New Product DOC1216
Calibration Factor =
𝑮𝒓𝒂𝒗𝒊𝒎𝒆𝒕𝒓𝒊𝒄 𝑭𝒊𝒍𝒕𝒆𝒓 𝑻𝑾𝑨
𝑺𝑴𝟏𝟎𝟎𝟒 𝑻𝑾𝑨