Handling of nanoparticles

Work in a fume hood or safety cabinet

Nanoparticles must not come into contact with the skin. As nanoparticles can penetrate a variety of common gloves, it is recommended that you wear 2 pairs of nitrile gloves, when you work in a closed system such as a fume hood, or the safety cabinet. The nanoparticles can attach to the outer gloves, so they must not leave the fume hood. In order for the nanoparticles not to stick to your lab coat sleeves, it is recommended to work with tight-fitting protective sleeves or long nitrile gloves, that do not leave the fume hood. Your lab coat must not leave the laboratory. Safety glasses must be sealed to the eyes.

Because of the gaseous properties of nanoparticles, they will easily leave the fume hood / safety cabinet, by the presence of turbulent airflow caused by e. g. traffic, it is necessary to establish a dedicated laboratory for handling of airborne nanoparticles, where no other activity occurs while handling. It is extremely important to work with slow-motion movements, when working with nanoparticles, so that the airflow is not disturbed. Therefore, plan your workflow so you have everything in reach and you do not have to leave the fume hood before the process is complete. It’s a good idea to work with an associate colleague, who can pick up forgotten equipment for you.

It is a good idea to apply wet cloth in the bottom of the fume cupboard, which can catch up with any waste. Keep in mind that no laboratory equipment leaves the fume hood before it is flushed and clean. This also applies to materials, litters, chemicals, etc. that must be wiped on the outside before removal.
If case of spill outside the fume hood, the room must be evacuated, and a waste kit, together with protective equipment for a full protection (see below) must be available in a suitable place.

Work outside the fume hood or outside the safety cabinet.

In special cases, nanoparticles can’t be handled in a closed system, such as a fume hood or safety cabinet. In these cases it is necessary to provide full protection to all employees in the room. However, it is possible to shield the area of handling (corresponding to, for example, an asbestos tent). A control measurement will be able to determine, whether it is only in the shielded area, that full protection is necessary.

A full protection consists of dust-repellent coveralls with hood, feet, long tight sleeves, 2 pairs of nitrile gloves, tight-fitting full-face mask with either P3 filter or breathable respirator.

At normal working condition, and for shorter periods of time, and with small amounts of nanoparticles, tight-wearing personal disposable masks with P3 filters, and tight-wearing safety goggles, can be considered to be sufficient to capture nanoparticles. However, it is recommended to use the full mask with P3 filter, in order to prevent other facial skin contact.

If required in the risk assessment, respiratory protective equipment can also be used. It is typically used when handling the more hazardous nanofibers (e.g. carbon nanotubes), or when handling large amounts of nanoparticles (> 4-5 g), or if protection from other chemicals are needed.

Thus, when working outside technical protective equipment, the room itself or the defined area (e. g. inside the tent), is considered to be the closed system. Access to the room / defined area must be accessible via locks, and bath facilities.

Contaminated equipment, etc., should be thoroughly rinsed before dispensing. Contaminated clothing etc. must be sealed in soluble washing bags before leaving the sluice and sent to wash. To prevent the spreading of particles into other rooms, all material etc., which is to pass through the sluice, must be cleaned and wiped on the outside with a wet cloth.

Depending on the cleaning procedure in the room or within the defined area, all entrance doors, must be signed in regards to the danger and the required protective equipment, in order to warn others. This applies to both in and out of operation.

Change of HEPA filter or maintenance of ventilation
Based on the risk assessment, the Institute is responsible for preparing an instruction for the change of Hepa filters and a schedule for the frequency thereof. This is done in cooperation between the nano-responsible at the Institute and Campus Service, and if needed with sparring from CAS-AB. The following issues can be included in the preparation of the instruction.

During maintenance work, e.g. change of HEPA filter or ventilation duct repair, the personal protective equipment described in the instruction must be used. It must be evaluated whether it is necessary to evacuate, shield, or shut down the area, before work commences. This is among others dependent on other ventilation.

The pressure differential on a Hepa filter should normally be checked annually, but it may take place more often depending on the particular nanoparticle or volume involved.

The actual change of HEPA filter must take place in a way so that the invisible nanoparticles do not spread. To minimize dispersion, the filter should with slow movements be enclosed in a sealed bag as fast as possible. The area is thoroughly cleaned for invisible nanoparticles by wiping all surfaces with a wet cloth, which is then disposed of in a sealed bag. Vaccuuming is not permitted.

When the entire room is exposed to nanoparticles, full protection is required. The area must be shielded, e.g. with locks, so the spreading is minimized. In the presence of nanoparticles throughout the room, all entrance doors must be signed for access restriction and which personal protective equipment is required. Once the room is released by a control measurement, the signage can be removed again. The risk assessment must describe how a room is released to allow full access without protective equipment.

All internal and external craftsmen who come in contact with nanoparticles in their work at DTU must be instructed in the risk. The duty to instruct lies upon the one that have requested the craftsmen. In cases where Campus Service performs the task, CAS has a duty of instruction, also towards external craftsmen. Internal and external craftsmen must sign that they follow the written local instructions and procedures for how to work safe.

Keep in mind that it may be a challenge that external employees do not take the risk seriously as they can’t see or feel it.

Link to coverall with hood and feet: (Tyvek Classic Plus)
https://www.icmsafety.com/da/personlig-sikkerhed/dragter-engangsartikler/dragter/tyvek-classic-plus-beskyttelsesd-91