Particulate matter -

Normal, environmental particulate matter may be harmful to some products. Dust, pollen and cigarette smoke can, over time, foul the mechanical (and in certain cases the electronic) components in products.

Other particulate materials, which developers need to consider are acidic/corrosive sprays, fog, gasses (inert/volatile) and ice crystals (fluids are considered below). These are mostly externally generated, but some products may also produce particulate matter themselves. For example, paper shredders or machines that handle material from which particles are emitted can unintentionally pollute the local operating environment in which other products are operating.

Two industry standards, which consider the protection of products from externally generated particulate matter are:

1. IP (Ingress Protection) of enclosure classifications; http://www.ul.com/hazloc/ref/ingress.htm]
2. NEMA (National Electrical Manufacturers Association) enclosure standards; http://www.nema.org/stds/aboutstds/upload/FAQ-Enclosures.doc/].

There are also standards controlling the containment of internally generated particulate matter. These standards are for products where such 'expected' generation is always specified when developing a product: for example see:
http://www.machinerylubrication.com/article_detail.asp?articleid=447&relatedbookgroup=ContaminationControl and http://www.iso.org/iso/iso_catalogue/catalogue_tc/catalogue_detail.htm?csnumber=2610