Crystalline silica is omnipresent in various activity fields such as construction, quarries, glassworks or even foundries. In the form of alveolar dust, if inhaled it represents a real danger to workers’ health. Our experts will show you the characteristics of this harmful dust and the respiratory protection equipment to use.
The dangers of silica
What is crystalline silica?
Silica is an element present in a large number of minerals in different forms, in particular crystalline or amorphous. Its pure form crystallizes under different temperatures and pressure conditions. Among them: quartz, tridymite and cristobalite.
Crystalline silica is a ubiquitous element in the earth's crust. Indeed, it is also found in many mineral origin construction materials such as sand, granite, concrete, stone, etc. With a less than 5 micrometers (microns) size, respirable alveolar dust (defined by its ability to reach the pulmonary alveoli) from crystalline silica is generated by many professional activities. It represents a real health hazard when inhaled.
Health effects
Crystalline silica is classified as a known human carcinogen (group 1). Exposure to this type of dust and its inhalation can cause many health problems:
- skin irritations
- eye inflammation
- bronchitis
- emphysema
- tuberculosis
- immune system damage
- autoimmune diseases
- lung cancer
- silicosis
Potentially lethal, the dangerousness of this substance for the body implies taking safety measures for all exposed persons.
Exposure situations
Exposure to crystalline silica dust is an omnipresent risk in a large number of activity fields, particularly on construction sites and in certain workshops. In France only, the ANSES (French National Agency for Food, Environmental and Occupational Health Safety) estimates that nearly 365,000 workers are affected by exposure to this element in their professional activity.
Professional fields concerned by the crystalline silica risk:
- Construction / Building works
- Stone cutting
- Cement production & use
- Ceramic and porcelain production
- Glassworks
- Dental prostheses production
- Foundry
- Plastic production
- Mines and quarries
Silica: regulation and prevention
Regulations
The dangers induced by the presence of crystalline silica in many professional activities lead to strict regulations. In France and in Europe, exposure to this substance is limited by law to specific levels.
| Occupational exposure limit value over 8 hours | |
| Crystalline silica: | OEL mg/m3 |
| alveolar quartz dust | 0,1 mg/m3 |
| alveolar cristobalite dust | 0,05 mg/m3 |
| alveolar tridymite dust | 0,05 mg/m3 |
Moreover, since 1997 crystalline silica has been classified as a carcinogen by the IARC (WHO International Agency for Research on Cancer). This classification and its recognition by the various national authorities entail specific regulatory obligations for CMR agents (carcinogenic, mutagenic or reprotoxic) for employers.
Silica danger prevention
Faced with the dangers of crystalline silica and the regulations in force, prevention plays a key role in the various applications exposed to this type of respirable dust. Many arrangements can be made to minimize the generation of this dust in work environments. Among these means of collective protection and security measures, we note:
- wet work
- workstations isolation
- use of dust extraction booths
- mechanization of hazardous tasks
- risk assessment
- working atmosphere control
- reinforced monitoring of exposed workers
- complete cleaning of exposed areas
- use of PPE (personal protective equipment)
- proper maintenance of the used PPE
Finally, in addition to these preventive measures, like asbestos respiratory protection, concerned people (employees, workers) must systematically be informed of the risks incurred in presence of crystalline silica.
Silica protective equipment
Crystalline silica exposure prevention methods should be accompanied by personal protective equipment. The use of a respiratory protection mask as well as wearing an dust suit ensures minimal exposure to the hazard.
The silica respiratory protection mask
In addition to the various prevention measures, wearing a respiratory protection mask specially adapted for fine particles is essential to ensure workers’ safety when exposed to crystalline silica.
The GVS Elipse mask
Today there are few dust masks able to filter ultra fine particles. In fact, most gas mask filter manufacturers offer equipment that filters particles in the 1 to 0.6 microns range. Respirable crystalline silica dust with a less than 5 microns diameter, with particles up to 0.3 µm regularly present, is therefore not filtered by these protective devices. Exposure to this type of particles requires the use of very high performance filters.
For this purpose, our experts recommend the use of the GVS Elipse mask with its P3 filters.
This respiratory protection mask is ergonomic, easy to use, very comfortable to wear and has high precision filters. GVS mask technology deploys a HESPA® (High Efficiency Synthetic Particulate Airfilter) multi-layer pleated filter. These P3 filters have a minimum efficiency of 99.95% or more for 0.3 micron particles. They have a 40 Nominal Protection Factor (PNF) (reducing the dust concentration between the outside and inside of the mask by 40). These filters are effective up to a maximum concentration of 50 times the OEL. All these properties make this mask ideal for protection against alveolar crystalline silica dust.
Supplied air respiratory protection
In places with a high concentration of crystalline silica, supplied air respiratory protection is recommended. Two types of equipment can be used to provide healthy breathing air in highly contaminated environments: the supplied air mask and the self-contained breathing apparatus.
Supplied air respirators - also known as SARs or airline respirator - are respiratory protective equipment that provide the highest protection level. Well-suited for many industrial applications, supplied air respirators are ideal in hostile, poorly oxygenated environments as well as areas with extreme concentrations of a pollutant (paint booths or asbestos removal sites). The supplied air mask is connected to a source of breathing air such as a compressed air cart or an air network. This type of system is very commonly used indoors in long lasting applications generating a high concentration of harmful dust.
The SCBA self-contained breathing apparatus consists of a mask connected to a compressed air cylinder worn on the back or on the side using a harness. Wearing an SCBA is not widespread for work generating crystalline silica, however short-term workers may be equipped with this PPE. For example, for emergency interventions, the SCBA is an integral part of the industrial firefighter's equipment.
The dust protective suit
To maximize protection against crystalline silica particles, wearing a dust suit is also recommended. This type of PPE, a chemical protective suit or HAZMAT suit, provides a barrier against respirable dust exposure. This reusable or disposable protection should be used to prevent contamination by particles and their transport outside the workplace.
Our team of experts recommends wearing an SPC 4X00 suit if crystalline silica is present. This series of personal protective equipment provides a barrier against splashes and ultra-fine particles such as respirable alveolar dust. It is a reusable personal protective equipment suitable for a wide range of applications generating hazardous dust. These suits are available with a hood, a face cuff or as a full suit with visor allowing easy use of a gas mask, a mask connected to a supplied air device or a self-contained breathing apparatus. This range of Dräger chemical suits offers excellent performance with very high comfort.
For convenience, it is also possible to wear a disposable protective suit against exposure to crystalline silica dust. In this case, our experts recommend wearing a single-use protection such as the Dräger SPC 3700 suit. It is a type 3 dry chemical suit with constant flow. It is worn with the CVA 0700 ventilated jacket and connected to a breathing air supply system. The ventilated jacket allows breathable air to circulate inside the suit and thus offers incomparable comfort. With simple operation and low maintenance, the Dräger SPC 3700 suit is ideal for many jobs that generate respirable dust.
GazDetect is at your disposal for the selection of your chemical suits and respiratory protection equipment. Do not hesitate to contact us for information or to request a quote.