You may be surprised to learn that dust inhalation over a long period can even be fatal. Silica dust is among the most dangerous dust types of dust and over two million people are exposed to it every year. Before we proceed, however, let’s understand what silica essentially is.
Silica, at its core, is a blend of oxygen atoms and silicon and is available in 2 different forms, namely: non-hazardous amorphous or hazardous crystalline. Crystalline silica is incredibly dangerous and can cause fatalities.
Crystalline silica is among the earth’s most minerals and is found in gravel, clay, stone, sand, rock andother natural materials. Most of these materials are used for making landscaping and building materials like plastic composites, ceramics, glass, concrete, roof slate, les and bricks. Silica dust is also there in numerous construction tasks like tunneling, quarrying, mining and excavating.
Silica is quite safe if it is within its original material. However, if disturbed, it can become an incredibly dangerous workplace hazard.
Silica dust exposure is a massive hazard, particularly in rock mining. However, it can also be problematic for those in the gas and oil industry, mainly due to hydraulic fracturing. Exposure to this dust type can result in chronic pulmonary obstructive disease, silicosis and lung cancer. Therefore, it is vital to have the right monitoring equipment, ensuring no one is exposed to it.
Similar to most of types of lab sample analysis, you need to collect a sample from locations with the highest risk of having silica dust. The sample can include diesel particulate, coal dust or silica and should be sent to a reputable lab for in-depth analysis. Most labs use X ray diffraction techniques to analyze silica dust.
Two of the most important things you need before sampling silica dust are fundamental knowledge and references about the industry regulation and standards. OSHA’s silica standard consists of the guidance and requirement to develop your exposure control plan.
An in-depth exposure control plan details the possible exposure risks in the workplace along with different ways to minimize exposure. Some of the most popular methods include work practices, housekeeping, engineering controls, limiting access to any area with high silica dust exposure. The Occupational Safety and Health Administration wants the written plan to include the following:
- Each task performed by employees that could lead to respirable silica dust exposure
- Every factor that impacts exposure, along with environment and material where the task will take place
Certain instruments are capable of spotting areas with the highest silica dust exposure and can also locate its potential sources. More often than not, companies acquire the services of IH consultants for creating an exposure control plan in written form.
The following is a list of item one needs for sampling silica dust:
- A PVC cassette (unweighed)
- PVC cassette (pre-weighed)
- Dust sampler that meets ISO and CEN criteria
You can use scheduled monitoring or performance monitoring options to test for crystalline silica. If required, you can try both tests, as long as the results are accurate. If you opt for performance testing, you will need to carefully test the air of the area where workers spend most of their time on duty. Doing so can provide an accurate reflection of the silica dust exposure during regular shift timings. The scheduled monitoring method, on the other hand, gathers air samples from breathing zones to highlight exposure to silica dost during different times, in various job capacities, across numerous work areas. This method also uses follow up samples at particular intervals. These follow ups are based on if the initial readings displayed levels over the 25 μg/m3 minimum threshold. No matter which testing method you choose, make sure to repeat the process in case engineering
controls, processes or personnel change.
Here is how The Occupational Safety and Health Administration’s website describes the silica dust sample collection process:
- A seasoned specialist, like a certified industrial hygiene specialist uses a dust sampler for collecting silica dust particles
- This monitoring sampler is wearable and placed on employees with the help of a collection tube. The tube is placed almost ten inches away from the worker’s mouth and runs through their clothing. In some cases, the tube is attached to a safety vest pocket or the employee’s back
- The employee being tested must continue wearing the device during their entire shift, which is usually around eight hours. Doing so will help them gain a TWA (total weighted average)
- Either every employee can wear the sampling device or only a select few who are close to the dust source. An industrial hygienist may help determine the ideal way to sample employees.
- Once the sampling period is over, the unit must be shut down and the filters should be removed to ensure a certified laboratory can analyze the samples
The certified lab performing the silica dust test must have sanctioned procedures mentioned in the analytical methods mentioned below:
- MSHAP-7 (IR)
- MSHAP-2 (XRD)
- NMAM 7603 (IR)
- NMAM 7602 (IR)
- NMAM 7500 (XRD)
- OSHA ID-142 (XRD)
It is also worth noting that the lab should be accredited to the INS/ISO/IEC standard 17025-2005. Plus, the lab must utilize NIST (National Institute of Standards and Technology) traceable standards when it comes to verification and instrument calibration. When using any of the analytical methods, the samples are analyzed for cristobalite, quartz and crystalline silica polymorphs. All of these are Group 1 carcinogens according to IARC International Agency for Research on Cancer. The above-mentioned sampling methods effectively remove non-RCS components affecting the analysis.
Sample pumps gather air samples by extracting air from a cyclone. There are different types of cyclone and each variant allows particles of different sizes to pass. The sample pump catches the bigger particles, whereas the smaller ones are collected in a filter. These particles are then analyzed in a lab. It is worth keeping in mind that gravimetric samples are needed before an assessment begins and at the end for proving OSHA compliance.
You may be wondering why not just use this method to sample silica dust every time. Well, the processing, collection, along with the lab analysis of gravimetric sample often takes weeks. Plus, according to OSHA’s standards, silica dust sampling must be performed at particular frequencies and time intervals for different compliance methods. In case there are any changes in engineering controls, the sampling process should start again to ensure the workplace complies with the set standard.
As you would expect, repeated tests make this form of sampling quite expensive and )me consuming,par)cularly for large companies. This is why many organiza)ons opt for real-)me monitoring as it is cost-friendly and fast. By verifying whether the adjustments made prior to the final gravimetric sampling areeffec)ve, you can steer clear of expensive surprises.
Since OSHA requires gravimetric sampling for reference data, many wonder the reason behind opting for real time monitoring. Well, the answer is pretty straightforward, direct reading, real time instruments offer a short path to compliance. Additionally, making adjustments and assessments to the engineering controls prior to gathering final gravimetric samples tends to be significantly more effective.
Since real time instruments offer information regarding exposure levels right away, the alerts can warn staff members about unsafe conditions right away. The in-depth data that real time instruments provide can help with accurate reporting, ensuring organizations can adjust their engineering controls if necessary. The real time results can be helpful for employers who want to a quick and cost-friendly assessment procedure to minimize risk and protect the workers.
OSHA has a gravimetric sampling requirement for proving compliance to silica standards. Making use of the real time monitoring method increases confidence in the gravimetric sample’s final lab analysis and demonstrates highlights successful compliance and management of silica exposure rules.
Your site, materials and process are among the most essential variables to determine the ideal location for real time instruments. In some situations, you may need to get help from a professional IH as they can create a well thought out exposure control plan, which may identify the locations and tasks to monitor silica dust.
According to OSHA’s standards, an individual who is capable of identifying foreseeable and existing silica hazards can conduct a silica dust exposure program. This person must have the knowledge, authority and most importantly, the ability to eliminate or at least minimize silica dust hazards without any hassles.
She or he must implement the exposure control plan as specified by the employer. What’s more, the person conducting the program is responsible to regularly inspect job equipment, materials and sites.
OSHA’s standards do not have any criteria regarding how many people an employer can hire for a silica dust exposure program. Therefore, employers can appoint any worker to oversee the program as long as they meet the qualification criteria.
That said, the qualifications could change based on the equipment and task. Most organizations appoint
a competent individual for each shift and job site and the amount of people assigned for the job usually varies, depending on the project and company size.
As mentioned abundantly, breathing in and inhaling silica dust us quite dangerous and can cause numerous health problems, especially if you don’t implement the right dust control measures in the workplace. Employees working in environments exposed to silica dust can suffer from chronic and acute diseases.
After some time, employees can even develop disabling and debilitating lung diseases. However, the dangers of excessive exposure to silica dust are far beyond merely lung disease. It can even result in problems like:
- Autoimmune diseases
- Kidney diseases
- COPD (chronic obstructive pulmonary disease)
- Chronic renal disease
- Lung cancer
- Chronic silicosis
The World Health Organization and the National Institute of Health believes crystalline silica is a human carcinogen and eliminating it from workplaces is possible with the help of accurate tests from a reputable lab. Mentioned below is a list of industries that have a high risk of silica overexposure:
- Stone and cut stone products
- Paintings and coatings
- Asphalt product manufacturing
- Hydraulic fracturing
- Maritime work
- Jewelry production
- Concrete products
- Pottery products
While testing for silica dust is vital to protect everyone from it, preventing it altogether is equally important, if not more. One of the most essential measures to prevent silica is controlling the amount of dust that comes in. Merely using a water hose to prevent the dust from becoming airborne is an effective dust control measure. Here are some effective methods to control silica dust:
- Take advantage of dust collection systems for any equipment that generates dust. When choosing equipment, make sure you search for dust control features. Also, utilize local exhaust ventilation for ensuring the dust isn’t released in the air. If your equipment’s dust control system isn’t working properly, avoid using it until fixed
- When rock drilling, consider using water from the drill stem. Doing so will minimize the dust from the air. Alternatively, you can also opt for drills with dust collection systems to control silica dust effectively
- Use cabinets, blast cleaning machines and other containment methods for preventing dust from entering the air
- Make sure you use healthy work practices to lower silica dust exposure. For instance, if your equipment contains dust, remove it with the help of a water house instead of compressed air. You can utilize vacuums with HEPA ( high efficiency particulate air) filters or try wet sweeping rather than dry sweeping