Electrostatic filters deemed inadequate

The three-minute standards test says nothing about the filter at actual work

The French National Institute for Research and Safety (INRS) have announced that electrostatic filtering devices do not live up to their promise, even though they pass European Standards.

In conjunction with the German BIA and the filter manufacturer 3M, the French authority conducted tests that showed a ten-fold degradation of some electrostatic filters during the course of just over an hour. This rapid diminution in personal protection could not be demonstrated by Standards testing, which only subjects filters to three minutes of exposure.

Serious shortcomings
The three-minute test is suitable for mechanical filters that only become more effective the longer they are used, while electrostatic types lose their efficiency with time. This could result in users falsely believing that they receive adequate protection from filters that become highly degraded after a very short time.
A press release entitled Dust Masks: a Dangerous Standard from the INRS refers to the "very low level of protection afforded by certain filters said to be electrostatic (including the P3 type) which nonetheless meet European Standards".

The document goes on to report that the three-minute test is "perfectly acceptable for mechanical filters that become more effective the more they are used, but is totally inadequate for electrostatic models".

The INRS has alerted French and European authorities so that all possible measures can be taken to ensure user protection. "If there is any uncertainty, INRS recommends that mechanical filters be used" the press release says.

Recommendations for now
The French labour ministry, Ministère des Affaires Sociales, du Travail et de la Solidarité, states that "under actual working conditions, the performance of some electrostatic filters, even those classed as ''highly effective'', deteriorates very rapidly over time", and that "a device classed as ''highly effective'' (P3) can become average or weak (P2 or P1) during its useful life".
The ministry goes on to make three recommendations: Change the classification of filtering devices, taking into account the characteristics of the materials used Require the instructions for the filters to prompt users to use electrostatic filters with care, and not to reuse such filters Ensure that filter labeling clearly states what materials are used, and the filter type (electrostatic, mechanical or mixed)

Massive lobbying
Marc Malenfer of the INRS says that the problem has been known for some time, and has been brought up several times at a respiratory protection committee of the EU commission.
However, massive lobbying from filter manufacturers has succeeded in thwarting a revision of the European norms. The European work group involved with the matter never reached a decision, and after many delays, the project was finally discontinued. Instead, the matter was shifted to ISO. Now, a respiratory standards work group called CEN-TC79 will speed up its handling of the question of electrostatic filtering devices.
Manufacturer resists changes at present, electrostatic filter packaging does not have to inform that the filters are of the electrostatic type, nor does it alert users as to the need to replace the filter often and not to reuse filters.
3M, the largest manufacturer of electrostatic filters, does not consider any changes to their packaging to be necessary. In the Swedish safety journal Arbetsmiljö, a spokesman from 3M says that the company cannot see any reason why it should have to do anything beyond following European regulations.

Sources:
Iotti, J-M, 2003, Filtres antiparticules: Une protection respiratoire conforme, oui mais..., T.S. journal, 09-03, pp 16-18

Koufane, N, 2004, Note to Members of the Commission for administrative cooperation on the market surveillance of personal protective equipment, République Française - Ministère des Affaires Sociales, du Travail et de la Solidarité

Malenfer, M, 2004, Dust masks: a dangerous standard (press release), INRS, 30 March

Actions taken by the French authorities

Due to these situation and of the seriousness of the topic ( public health, legal liability...) , the French authorities have decided to launch a safeguard clause.

In addition to that, the French Ministry for Labor has issued a warning to importers, exporters, distributors and Notified Bodies concerning the particle filters as which was published on 10.06.2004 in French official journal .

The French Labour Ministry considers that the conformity to the relevant EN is not anymore sufficient. The French authorities have requested EU Commission and CEN to rapidly revise these standards. In the meantime they request in particular that the filter penetration level shall not be assessed on the basis of the 3 min penetration test but after a 120 mg exposure to liquid and solid aerosols.
The new limit of use and instruction of storage shall be indicated on the package.
 A new market surveillance campaign will be launched in November 2004 and all product which will not be in conformity will be forbidden on the French market.
Five ENs are concerned which have to be amended according to the warning: EN 143, 149, 405, 1827, 13274-7 but no proper action has been taken by the TC/94/SC4 in the Roma meeting despite all official warnings.
The CEN/MC is trying again to put pressure on TC 79.