Silica health risks go beyond the oilfields

Silica-laden sand is used in fracking.Silica, hydraulic fracking in the news

Crystalline silica in the work place is in the news this month because investigation by public health officials indicates it may be a health hazard for workers involved in hydraulic fracturing [fracking].

OSHA hopes to issue new silica regulations this spring. [1]

Silica is found in soils, rocks and many minerals.

It can present health hazards to workers in many industries because silica dust can be inhaled into the lungs.

Fracking uses a silica-rich sand, sometimes called “frac sand”, that can release silica as airborne dust as it is moved and transported around the worksite. [2]

While hydraulic fracturing is a relatively young occupation, silicosis, a lung disease caused by inhaling crystalline silica, has been acknowledged as a disease since the nineteenth century.


Research indicates that the health risks associated with silica don’t stop with silicosis:  “Occupational crystalline silica dust exposure appears to be a risk factor for several diseases.” [3]

Human lung damaged by silicosis.

photo: CDC

Researchers indicated that occupational exposure to crystalline silica increases the risk of lung cancer, pulmonary tuberculosis and COPD (chronic, obstructive pulmonary disease) as well as kidney and autoimmune disorders. [3]

Silicosis damages your lungs and makes it hard to breathe, increases your risk of lung infections, and may lead to heart failure. Silica may also cause cancer. [4]

Silica is a health hazard in many occupations

In addition to fracking, other industry applications that use or release silica include: [5]

  • Metallurgy industry for foundry moulds, iron and steel castings, flux in smelting basic ores
  • Manufacture of fiberglass for electrical insulation, chemical filtration, and reinforcing fabrics
  • Released during refining sand for production of quartz
  • Ceramics industry dry clays, glazes, mould ingredients
  • Processing synthetic quartz
  • Manufacture of heat-resistant materials and building products
  • Manufacture of electrical instruments with piezoelectric properties [can acquire electrical charge]
  • Manufacture of optical equipment such as prisms and lenses
  • Used as paint extender, lining material for vessels used in the chemical industry and in aerospace
  • Released during granite and stone processing
  • Abrasive in polishing compounds, sand paper, and sandblasting

Silica dimensions

In nature, the particle size of silica seems to be greatly varied. [6]

Because silica is useful in many industries and applications, silica providers use various processing techniques in order to offer silica in specific particle sizes.

Permissible levels of silica

The OSHA permissible exposure limit to silica is approximately 0.1 mg/m3. [2]

In words, that’s one-tenth of one milligram per cubic meter — roughly 10% of 0.000003527 of an ounce per 35 cubic feet.

Filtration of particles

At Sentry Air, our application specialists work with our customers to identify the appropriate filtration system for the customer’s application.

Our air cleaners can be equipped with single or multiple types of particle filters.

MERV pre-filters

We offer MERV pre-filters in a range of efficiencies from 11 to 16.

The EPA says that MERV filters in the 11 – 13 range are “13 are reasonably efficient at removing small to large airborne particles.” [7]

Further, the EPA says that MERV filters rated 14-16 may be as efficient as true HEPA filters. [7]

HEPA filtration

Sentry Air HEPA filter.

Sentry Air HEPA filter.

HEPA filters can capture particles as small as 0.3 microns in particle size. Substances with particles that can be captured by HEPA filters include dust, spores, and pollen. has a nice explanation of HEPA filters and even includes a little history about them. [8]


ULPA filtration

ULPA filters can “remove from the air at least 99.999% of dust, pollen, mold, bacteria and any airborne particles” with a size of 0.12 microns or larger. [9]

Sentry Air ULPA filters are rated up to 99.9995% efficiency.

To compare the particle size of various substances, we offer a particle size chart on our website.

Give us a call

If you are concerned about silica particles in your process, give us a call at 1.800.799.4609, email us at, or fill out this online form to have a Sentry Air Systems Applications Specialist contact you to discuss your process.


1 Silica Rule Changes Delayed While Workers Face Health Risks

2 OSHA Infosheet: Silica Exposure during Hydraulic Fracturing

3 Occupational silica exposure and risk of various diseases: an analysis using death certificates from 27 states of the United States

4 Silica…It’s Not Just Dust: Silica Dust Causes Silicosis

5 Occupational Health Guideline for Crystalline Silica

6 Colloidal Silica—Determination of Particle Sizes

7 Guide to Air Cleaners in the Home



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