Silica: A Brief History

Silica: A Brief History

Two male industrial workers exposed to silica dust

Two male industrial workers who were inside a West Virginia ceramics factory, Public Domain Picture by CDC

From the day we’re born, taking a deep breath is something we all take for granted.  Silica in an industrial environment is common place.

Adults breathe 12 – 20 times a minute when they are resting.

As humans, we take between 17,000 – 30,000 breaths a day, and the total length of the airways in our lungs is estimated to be 1491 miles (2,400 km.) The equivalent of Denver, Colorado to New York City, NY in travel! However, every breath you take has the potential to cause silicosis.  Especially if you work in an environment where you are exposed to respirable crystalline silica (RCS).

What is silica?

Silica is a fundamental component of soil, sand, granite and many other minerals and is found in many places on Earth. The most common form of silica is Quartz (the other two have cristobalite and tridymite). All three forms create breathable particles when workers chip, cut, drill or grind objects containing silica.

Related article:  OSHA Publishes Silica Standard FAQ

Silica, is a primary component of the Earth’s crust, is present in a wide range of industrial and non-industrial environments and consumer products (including many cosmetics and cat litter).

The breathing of the silica dust generated from these activities can have a devastating effect on health, which can cause lung cancer and silicosis.

When we talk about the dangers of silica, the word “silicosis” immediately comes to mind.

Silicosis itself tends to be linked to mining. The weakening lung disease, caused by the inhalation of crystalline silica dust, has flourished in medical, political and social policy responses and has captured the public imagination expressed in popular culture, from mining ballads to representative art.

There are legitimate reasons for this – not least the massive harm to the lungs caused by the disease.  Silicosis has precedence of being a dangerous occupational disease and has made its mark in the mining industry in the global economy.

However, when it comes to silicosis, the mining industry is not the full story, and silicosis is not the primary disease when it comes to silica risks.

Since the 1990s, medical science has re-evaluated the potential role of silica in triggering inflammatory diseases, autoimmune diseases which include systemic lupus erythematosus, scleroderma, rheumatoid arthritis, and sarcoidosis. Although it was previously thought to be harmful only when inhaled in the form of dust, the question now arises whether exposure to silica in other forms can also be risky.

The road from safety to occupational health, industrial hygiene and well-being may be a long and winding road, but as practitioners, we get the hierarchy of control measures. If we all took the time to consider RCS and whether our existing control measures were designed to ensure routine maintenance and control of RCS, we would each contribute to reducing the number of people dying of silicosis and keep the worker safe.


OSHA Wants Your Opinion on Silica

OSHA Wants Your Opinion on Silica

OSHA put out a Request for Information (RFI) to ask for additional information regarding the respirable crystalline silica standard.  OSHA revised the silica standard March 25, 2016, and launched an industry compliance effort on September 23, 2017, with full enforcement of the October 23, 2017 standard.

Concrete workers at night

The U.S. Army Corps of Engineers working on Folsom Damn. Photo allowed from Public Domain by US.

The 2016 OSHA rule lowered the Permissible Exposure Limit (PEL) to 50 micrograms per cubic meter (µg/m3) of air as an 8-hour Time Weighted Average (TWA) in general industries.  OSHA considers that level to be technically achievable for affected industries.  In construction, OSHA put an Action Level (AL) of 25 µg/m3 over 8-hour TWA, among other requirements. The original OSHA standard established in 1971 had a PEL of 250 µg/m3 in the construction industry and 100 µg/m3 in general industry.

Related article:  OSHA Publishes Silica Standard FAQ

The OSHA standard for the construction industry is strict, and the criteria are listed in Appendix I: OSHA Respirable Crystalline Silica Standard for Construction.  Inside the appendix is a table of engineering controls, work practices, and respiratory protection specified for everyday construction job tasks that possibly release respirable crystalline silica. Employers that comply with the methods defined in “Table 1– Specified Exposure Control Methods When Working with Materials Containing Crystalline Silica ” are exempt from the PEL or demands for monitoring of employee worker direct exposures.  However, employers should be willing to protect workers.

OSHA Seeking Additional Information

OSHA has issued the RFI to solicit comments from industry on Table 1. OSHA described its plan in the Fall 2018 schedule of governing and deregulatory actions.  Regarding the Fall of 2018 agenda, OSHA said it had an interest in 3 details:

  • The efficiency of control determines not consisted of for tools and jobs listed in Table 1;
  • Tasks and even devices including exposure to respirable crystalline silica that is not noted in Table 1; and
  • The performance of dirt control methods in limiting employee exposures to respirable crystalline silica when executing those procedures.

In evaluating the responses to the RFI, OSHA will determine if alterations to Table 1 are ideal and needed.

Lower PEL Full of Controversy

Regarding the OSHA 2016 rule, the development of lower PEL was subject to controversy, debatable and probably would be challenged in federal court.

Nevertheless, December 22, 2017, the three-judge panel of the UNITED STATES Court of Appeals in Washington DC upheld the OSHA rulemaking with one exception, finishing a challenge by North America’s Building Trades Union and US Chamber of Commerce.  An agreement was made that OSHA’s medical removal requirements were arbitrary and instructed the agency to reconsider them.

What Should Employers Be Aware Of?

Employers that comply with the PEL are not subject to exposure assessment.  Construction industry employers should focus their efforts on the exposure control methods.  The exposure control methods are defined in Table 1 of the OSHA standard, however, methods not included in the standard should be avoided.  If an employer is not properly implementing the control methods OSHA will issue citations.

Have your employees wear a real-time DustCount 8899 – Respirable Dust Monitor – Click Here to Learn More

According to Bloomberg Environmental, a Virginia construction company was issued five citations for respirable crystalline silica violations totaling $304,130.  In other words, the fines could be the most substantial fines ever under the new silica standard.

For a full copy of the General Industry FAQ, please see this link ->

If you are an employer with respirable crystalline silica standard potential issues, you may want to monitor the RFI and provide comments and data to OSHA regarding the standard. Refer to the RFI here ->

OSHA Publishes Silica Standard FAQ

OSHA Publishes Silica Standard FAQ

As a result of the new and revised 2017 OSHA regulation for respirable crystalline silica, OSHA has been trying to clear any questions concerning compliance.

Master Sgt. Donnie Bogan saws cutting lines in concrete

Master Sgt. Donnie Bogan saws cutting lines in concrete, licensed under the terms of the United States Government Work.

The controversial crystalline silica guideline from OSHA took effect on June 23, 2016.  Industrial sectors had between one and five years to fully comply with the new standard.  The building and construction sector’s conformity day was Oct. 23, 2017.

The regulation lowered the Permissible Exposure Limit (PEL) required dust controls as well as safer work techniques and called for employers to offer respirators to employees when other safe job techniques were unable to restrict respirable crystalline dust exposure.

Employers need to evaluate the exposure of each worker that is or may reasonably be anticipated to be subjected to respirable crystalline silica at or above the authorized limit making use of either an efficiency alternative or a set up monitoring option.

According to Bloomberg Environmental, a Virginia construction company was issued five citations for crystalline silica violations totaling $304,130 USD.  The fines could be the largest fines ever under the new silica standard.

Recently, OSHA released a brand-new silica standard Frequently Asked Question (FAQ) to offer some clarification. The new FAQs were created after talking to the general industry and industry stakeholders.

The goal of the new silica standard FAQ is to give further guidance to both companies and employees on the silica standard’s requirements.  The areas highlighted are methods of compliance, exposure assessments, regulated areas, and communication of respirable silica hazards to employees.

Here are three frequently asked questions published in the OSHA General Industry FAQ.

Q: Can employers use data from real-time monitoring and exposure mapping to assess employee exposures under the performance option?

A: Yes. Data generated by real-time monitoring of respirable dust levels (conducted using direct-reading instruments) can be combined with exposure mapping to assess employee exposures under the performance option, provided that the data can be correlated with individual employee exposures and otherwise meet the requirements for objective data. OSHA notes that in order to estimate the level of respirable crystalline silica in the air using real-time monitoring data, employers must also know the percentage of silica in the dust (e.g., from the analysis of a bulk sample or information from a safety data sheet). If an employer does not know the percentage of silica in the dust, it can assume 100% of the respirable dust is silica for purposes of determining worst case exposures from real-time monitoring data under the standard.

Q: If an employer characterizes employee exposures under the performance option using objective data from real-time monitoring and exposure mapping, how often does the employer need to repeat the monitoring and mapping process?

A: The goal of the performance option is to give employers flexibility to accurately characterize employee exposures using whatever combination of air monitoring data or objective data is most appropriate for their circumstances. Therefore, OSHA has not specified exactly how often data should be collected for these purposes. Employers may rely on existing data as long as the data continues to be sufficient to accurately characterize employee exposures. OSHA notes, however, that accurately characterizing employee exposures is an ongoing duty, and employers must reassess exposures whenever a change in the production, process, control equipment, personnel, or work practices may reasonably be expected to result in new or additional exposures at or above the AL, or when the employer has any reason to believe that new or additional exposures at or above the AL have occurred. See 29 C.F.R. § 1910.1053(d)(4)

Q: If personal sampling results show that one employee, who works in a small, non-enclosed area of a large building, is exposed above the PEL, but another employee, who is only a short distance away, is exposed below the PEL, how does the employer decide how far to extend the regulated area?

A: Because there is an exposure above the PEL, the facility must determine which task or operation is creating the overexposure and create a regulated area around that task or operation. In the example provided, the regulated area may include only the first employee’s work station. If the second employee is not exposed above the PEL and is not reasonably expected to be exposed above the PEL, the regulated area does not have to cover that employee’s work area. An employer could choose to use area sampling, real-time monitoring, or exposure mapping to assist in identifying the boundaries of a regulated area.

Have your employees wear a real-time DustCount 8899 – Respirable Dust Monitor – Click Here to Learn More

For a full copy of the General Industry FAQ please see this link ->

Coal Mines Make Black Lung

Coal Mines Make Black Lung

Black Lung is still around.  

This last week the National Public Radio (NPR) collaborated with  PBS investigative series Frontline on an article titled:   “An Epidemic Is Killing Thousands of Coal Miners.  Regulators Could Have Stopped It.”  The multiyear investigation by NPR and Frontline found that these coal miners are part of an unfortunate, tragic, discovered outbreak of black lung disease, known as progressive massive fibrosis.

Ex Coal Miner with Black Lung

Ex Coal Miner with Black Lung, NARA/EPA via pingnews

Beyond mountain roads, deep in Appalachia, the article describes the familiar story of past coal miners, young and old, coughing uncontrollably and packing an oxygen tank on their back.  Children are wondering what is wrong with their rapidly aging parents and grandparents.  The concerned children watch them hack, cough, and spit up dead, black lung tissue onto the ground.  The lung tissue dies so fast that the respiratory therapists describe it as “peeling away.”

NIOSH, unfortunately, is seeing some trends in the extensive spread of coal workers’ pneumoconiosis (CWP, commonly called Black Lung).

The investigation suggests that for decades, the government regulators had evidence of excessive and toxic mine dust exposures but did nothing about it.

Thousands of cases of Black Lung are being reported to the National Institute for Occupational Safety and Health (NIOSH).

Yes.  It is 2019.  Black Lung should not be an occupational health problem in this time period.

According to Dr. Robert Cohen, a pulmonologist at the University of Illinois in Chicago, “the advanced stage of black lung leaves lungs crusty and useless.”  He has spent decades studying black lung and other lung diseases.

They’re essentially suffocating while alive.

The airborne poison that triggers serious condition isn’t coal mine dust alone. It consists of respirable crystalline silica, dangerous dust that is generated when miners reduced sandstone as they mine coal. Coal seams in central Appalachia are ingrained in sandstone which contains quartz; therefore when mining techniques reduce quartz, it produces respirable crystalline silica.  The silica is inhaled deep into the lungs where it is lodged permanently.

Miners Waiting for Their Examination at the Appalachian Regional Hospital in Beckley, West Virginia, U.S. National Archives and Records Administration

This excessive exposure to respirable crystalline silica almost certainly happened more often than the data suggests. Respirable crystalline silica sampling takes place during regular inspections, which are scheduled twice a year in surface mines and four times a year in underground mines.

The sampling should be occurring over 8 hours according to the OSHA Respirable Crystalline Silica Standard.

Related article:  OSHA Publishes Silica Standard FAQ

Most of the sick and dying miners that were interviewed used dust masks and said they often didn’t work.  With real-time monitoring of respirable crystalline silica masks only need to be worn during high levels of silica.  By analyzing minute particles, a dangerous level can be determined, and miners do not have to wear a mask all the time.

Have your employees wear a real-time DustCount 8899 – Respirable Dust Monitor – Click Here to Learn More

This investigation is a sad case of human illness that might have been prevented with adequate safety measure and monitoring.


An Epidemic Is Killing Thousands Of Coal Miners … (n.d.). Retrieved from

Dr. Alice Hamilton: Industrial Hygiene Crusader

Dr. Alice Hamilton: Industrial Hygiene Crusader

For National Women Physician’s day, we choose to commemorate the success of Dr. Alice Hamilton.  As consumers, we support a marketplace that allows us to acquire low-cost products quickly.  Sometimes production of those consumer products comes at a human health cost.  Alice Hamilton was a pioneer in the field of occupational health and safety.  There is no individual, male or female, that was much more instrumental in making the worker and employer aware of the occupational health and wellness dangers and prospective dangers of the industrial workplace than Alice Hamilton.

Alice Hamilton, 1893

Alice Hamilton in 1893, the year she graduated from medical school. PDH at Smithsonian Institution and en.wikipedia [Public domain], from Wikimedia Commons.

The Early Years

Alice Hamilton was born in Fort Wayne, Indiana in 1869 into a family with privilege.  Privilege did not make Alice Hamilton selfish, and she aspired to provide some type of useful service to the world.  She wasn’t always the best student especially in reading and science but she studied hard and made up the deficit.

She earned her medical degree from the University of Michigan in 1893.  In the 1890s, according to the census, there were about 4,500 female doctors in the United States.  It was extremely unusual for a woman to be a doctor but Alice persevered.

Pioneering Industrial Hygiene

In 1897, Dr. Hamilton took a setting teaching pathology at Northwestern University’s Female’s Medical Institution in Chicago. In the “Windy City,” she came to be associated with Hull House, the world-famous settlement residence founded by Jane Addams in 1889.   A settlement house brought the poor and the rich of society together in physical and social proximity.  As higher education opened to women, young female graduates brought their energy to the settlement movement.  She lived there for 22 years.

Deeply devoted to her work at Hull House, Dr. Hamilton additionally took on investigations of typhoid high temperature, tuberculosis and drug abuse in Chicago. In 1908, she was assigned to the Illinois Compensation of Occupational Diseases as well as, in 1911, to the U.S. Division of Labor. It was then that she began a vigorous search of what she called “exploring the dangerous trades.”

In 1919, Hamilton became the very first woman professor, in ANY field, at Harvard Medical College, albeit on a part-time basis.  New York times announced her appointment with the headline:  “A Woman on Harvard Faculty—The Last Citadel Has Fallen—The Sex Has Come into Its Own.”  Her rebuttal to this headline was:

“Yes, I am the first woman on the Harvard faculty—but not the first one who should have been appointed!”

Hamilton faced gender discrimination.  She was continually excluded from social activities, could not enter the Harvard Union, could not attend the Faculty Club, and did not receive football tickets. The worst thing was Hamilton was not allowed to march in the university’s commencement ceremonies with her male faculty counterparts.

In 1925, Hamilton testified at a Public Health Service conference on the use of lead in gasoline.  She warned of the danger it posed to people and the environment and especially children.  Nevertheless, at the prompting of big business, leaded gasoline was allowed.  By 1988, the Environmental Protection Agency (EPA) estimated that 68 million children suffered toxic exposure from lead in leaded fuels over the previous 60 years.

Dr. Alice Hamilton

Dr. Alice Hamilton, pioneer of occupational medicine in the United States. PDH at Smithsonian Institution and en.wikipedia [Public domain], from Wikimedia Commons.

Like a modern-day detective, Hamilton roamed the dangerous parts of urban America, descended into mines, and manipulated her way into factories reluctant to admit her.  Hamilton called it “shoe-leather epidemiology.”  She had a process of making personal visits to factories, conducting interviews with workers, and compiling details of diagnosed poisoning cases and utilizing the emerging laboratory science of toxicology.

Hamilton was the pioneer of occupational epidemiology and industrial hygiene. She created the specialized field of industrial medicine in the United States. Her findings from her research were well written and scientifically persuasive.  Regarding her research, she influenced massive health reforms that changed laws and improved the health of workers.

Hamilton’s best-known research included studies on:

  • Workers getting sick through contact with the explosive trinitrotoluene (TNT).
  • Steelworkers suffering carbon monoxide poisoning.
  • Hatters suffering mercury poisoning which caused mental illness and spawned the phrase “mad as a hatter.”
  • Jackhammer operators suffering debilitating hand conditions.
  • Limestone cutters suffering spastic anemia also is known as “dead fingers.
  • Tombstone carvers suffering a high incidence of pulmonary tuberculosis.
  • Matchstick factory workers suffering phosphorus necrosis of the jaw commonly called “phossy jaw.”

She uncovered the dangers in unsafe factories and workplaces with unconventional methods and fearlessly acting to become an advocate for a safe workplace in the industrial revolution.  Up until her death in 1970, Hamilton continued to campaign for the health of all Americans, leaving an enduring, positive and long lasting mark on the public’s wellness.

We should all strive to emulate her talents in listening attentively to those that think they do not have a voice.


Pin It on Pinterest