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Given the lack of general standards for hygienic finishes, specifiers must rely on their own experience and that of manufacturers and the NHS. Particularly useful is the 'NHS Estates' Health Technical Memorandum ºÚ¶´ÉçÇø Components series, available on the NHS Estates online service (www.tionestop.com).

The following criteria must be taken into consideration when specifying – and installing – healthcare scheme finishes.

   1 - Inherent resistance to spread of infection
Many applied finishes, such as paints and grouts, contain antimicrobial agents, mould inhibitors, fungicides or other infection-resistant agents.

Textiles can also be treated with these agents, and materials such as wood have a minor natural capacity of this kind.

However, some agents only target a small range of microbes, so broad-spectrum products are preferred, which are resistant to a wide range of infections. It is important that the resistance lasts the installed life of the product or can be reinstated at a later date.

When specifying plastics, consult the following two standards: ISO 846:1997, on evaluation of the action of micro-organisms, and ISO 16869:2001, on the effectiveness of fungistatic compounds. The standard prEN 927-5:1998, on liquid permeability of coating materials, may also be relevant.

   2 - Cleanability
Specify finishes with a smooth texture and a non-porous or impervious surface, and minimise joints. Smooth finishes are less likely to absorb liquid and microbes, to stain and to retain dirt. Less aggressive cleaning methods can be used, and cleaning will be needed less often. Finishes should have no corners, ledges or crevices where debris could accumulate. Flush junctions across finishes, and between finishes and planes, are important.

   3 - Chemical resistance
Finishes need to be able to resist aggressive cleaning regimes such as steam hosing and solvent cleaning. Resistance to other chemicals also needs to be considered. Floors, in particular, must be able to resist spills of chemicals used by medical staff, and spills of body fluids such as blood and urine.

Many standards deal with this issue. Two specific standards to be aware of are prEN 2434-02, which specifies high chemical-resistant polyurethane finishes, and BS EN ISO 2812-1:1995, a test method for determining the resistance of paints and varnishes to liquids.

  4 - Controlling emission of contaminants
Some materials emit toxic substances in service. For example, solvents may be emitted as finishes, adhesives and sealants cure. This is usually a short-term problem. Toxic chemicals may also be emitted as a result of chemical reactions in service, for example to dampness in substrates, or to cleaning chemicals or spills.

Emissions from materials can be determined using tests developed in Finland for emission classification of building materials: Saarela, K et al (2002) Emission classification of building materials: Protocol for chemical and sensory testing of building materials, Rakennustietosaatio, Helsinki. Another relevant standard might be NES 713, on toxicity of materials (used by BRE). The Control of Substances Hazardous to Health Regulations 1999 should be consulted. The ºÚ¶´ÉçÇø Regulations Approved Document D: Toxic Substances deals only with UFF cavity insulation.

   5- Durability
Finishes should be able to resist wear and damage. If a surface deteriorates it may support microbes and resist cleaning. For floors, this arises mainly from traffic; for walls, it arises from impact; and for suspended ceilings, it arises from the frequent removal and replacement of tiles as services are maintained.

The NHS offers its own test methods for flooring (in HTM ºÚ¶´ÉçÇø Components 61: Flooring, 1995) that is particularly prone to failure. One test looks at resistance of the installed floor to static loads and another looks at resistance to mobile loads. The redesign of mobile furniture can significantly improve the lifespan of the flooring – by, for example, using larger, softer wheels.

   6- Repairability
Check that materials specified can be repaired. Some materials have a minor self-repair capacity, for example small cracks in lime-based cements. Others, such as timber or cements, can be repaired fairly easily while maintaining hygiene integrity. But some materials are problematic. For instance, lifting or damaged sheet materials probably need to be stripped and replaced.

   7 - Low-impact installation
Often finishes are applied in occupied hospitals. In these circumstances it is important that the work should not greatly impact on the hospital or its patients. For example, dust generation during installation should be minimised, as should emission of volatile organic compounds, which contribute towards poor air quality. The work should be completed as quickly as possible.