1.1. How to determine whether a demolition site will expose workers to silica dust
Respirable crystalline silica enters the body when dust containing a proportion of crystalline silica is inhaled. When the particle size range of the dust is sufficiently small (such that the particles fall within the respirable fraction), the dust will travel deep into the lungs. It is at this point that respirable crystalline silica can cause health effects.
Occupational exposure to respirable crystalline silica can occur in any workplace situation where airborne dust is generated, which contains a proportion of respirable crystalline silica.
The possible presence of fine particles of crystalline silica means that there may be a risk. If there is no foreseeable risk, then specific measures do not need to be taken. However, general principles of prevention should always be obeyed.
In this regard, the presence of silica dust should be expected in demolition sites where any of the following materials are to be handled:
- Silica containing composites, e.g. manufactured stone
- Concrete, mortar
- Tile
- Slate
- Granite
- Bricks
Regarding the tasks where silica dust may be generated and therefore present a risk to workers, the following table, is an example and may be helpful when assessing whether the processes in the workplace may cause the generation of fine particles which, if airborne, could lead to personal exposure to respirable crystalline silica.
| POTENTIALLY RISKY TASKS DUE TO THE POSSIBLE PRESENCE OF SILICA DUST | |
| PROCESSES | Where may fine particles be generated? (Non-exhaustive list) |
| GENERAL DEMOLITION OPERATIONS |
|
| STORAGE AND STOCKPILING |
|
| LOADING AND TRANSPORT
|
|
| MAINTENANCE | Activities requiring dismantling/opening/access to equipment, or entry into dusty process areas. |
1.2. What legislation is in force regarding exposure to silica dust?
In January 2018, the European Commission issued a revision of the Carcinogens and Mutagens at Work Directive (2017/2398/EC). In Article 18a, Annex I, which defines the list of substances, the following point has been added: “6. Work involving exposure to respirable crystalline silica dust generated by a work process”.
The Directive implements a binding Limit Value of 0.1 mg/m³ on those “works involving exposure to respirable crystalline silica dust generated by a work process”.
On 17/01/2020, Directive 2017/2398 finally came into effect on the protection of workers from the risks related to exposure to carcinogens or mutagens at work.
So, this limit is already in place in many EU Member States, with some member states even implementing a lower limit.
1.3. How workers can be protected against silica dust exposure
There are several actions companies can take to manage the amount of dust created and minimise exposure to silica dust among workers. The most common are compiled in the tables below:
| PREVENTION ACTIONS TO PROTECT THE WORKER FROM SILICA DUST | ||
| Enclosure | Conducting silica dust-producing processes in a sealed environment | |
| Water | Keeping processes wet to prevent dust from becoming airborne | |
| Extraction/Ventilation | Ensuring that RCS is extracted and stored for secure removal | |
| Protective equipment | Preventing dust from being breathed in (eg. face masks) | |
| Good hygiene | Washing work clothes and vacuuming up dust produced by processes | |
| Specific equipment | When grinding, scarifying or blasting materials that contain silica, the machine should be equipped with a local dust connection, which will allow it to work dust-free when connected to an appropriate dust collector | |
However, if silica dust generation is expected, an assessment of personal exposure levels should always be carried out, considering the dust control measures that are going to be implemented in the workplace. To perform this assessment, the steps in the table below should be followed.
| ASSESSMENT OF PERSONAL EXPOSURE LEVELS TO SILICA DUST | |
| 1 | Identify the substances and processes in the workplace which may give rise to the generation of airborne respirable crystalline silica dust |
| 2 | Identify which workers may be exposed, in which locations and under what circumstances this exposure may occur |
| 3 | Identify the frequency and duration of exposure for each worker exposed |
| 4 | Identify existing control measures |
| 5 | Carry out personal exposure monitoring |
| 6 | Compare the results to the relevant exposure limits |
The only way to quantify the amount of respirable crystalline silica present in the workplace atmosphere is to perform a sampling of the air and analysis of the dust collected. Occupational exposure assessment is the process of measuring or estimating the intensity, frequency, and duration of human contact with such contaminants.
There are two types of measurements commonly used:
- Personal
- Static
Both types of measurement can be used jointly as they are complementary. It is up to the experts designated by the employers and the employees’ representatives to opt for the most adequate solutions while respecting the national and European provisions.
General requirements for dust monitoring are determined in the European Standards EN 689 (Workplace exposure – Measurement of exposure by inhalation to chemical agents – Strategy for testing compliance with occupational exposure limit value) and EN ISO 13137 (Workplace atmospheres – Pumps for personal sampling of chemical and biological agents – Requirements and test methods).
In line with this, it must be noted that machines can be equipped with a vacuum measurement system that will allow the machine to automatically stop when the vacuum inside the dust hose is too low. This device makes sure the dust collection system is sucking up all the dust, thus creating a safe & dust-free environment.
Moreover, it is worth noting that an easy way for operators to not be in direct contact with hazardous dust is to use remote-controlled machines. In this way, they can operate the machine from a safe area.