Book - School of Science and Technology

8 FundamentalsTable 1.4 Examples of outside air qualityAir qualityCarbon dioxide(mg/m 3 )Carbon monoxide(mg/m 3 )Nitrogen dioxide(mg/m 3 )Sulphur dioxide(mg/m 3 )Particulates(mg/m 3 )Excellent 680 0±0.2 2 1 100SourceCEN Report 1752, Dec. 1998.Table 1.5 Indoor contaminantsBasement car parks Furnishings Office machines acarbon monoxide artificial fibres ammoniaCleaning agents formaldehyde formaldehydebleaches carpet dusts ozonedeodorants Occupants paper dustdisinfectants carbon dioxide methanolsolvents water vapour nitropyreneCooling towers clothing fibres trichloroethyleneLneumophila biological aerosols tetrachloroethyleneodoursBuilding productsActivitiesfootwear dirtmaterial emissionsoccupational process tobacco smokegluescombustion productscooking fumesMoulds and micro-organismsMost common in indoor air:bacteriavirusesactinomycetesMost common in indoor:bacteriaactinomyceteshouse dust miteNotea Photo-printing, copying, duplicating and correcting fluids, etc.indifferent or absent maintenance effort, may well be ineffective. Careful siting and designof ventilation air intakes is required to minimise contamination from external sources.*Pollution generated within a commercial building may be from any combination of thesources listed in Table 1.5. Airborne bacteria use dust particles as a form of transport and,if housekeeping is neglected, may present a health hazard. Contaminants are identified bysize, the micrometre (mm) being the common unit used for air filter rating.For new construction sites, any evidence of ground source contamination from landfillsites or occurring naturally, such as radon, should be determined and precautions taken toavoid risk to the future occupants. In recent years a considerable amount of research hasbeen carried out into the combined effects of different pollutants. y,z Generally it has beenfound that cooler drier air is perceived to be less contaminated with the sensation offreshness reducing with increasing humidity and temperature.* Minimising pollution at air intakes, CIBSE Technical Memorandum TM21:1999.y Fanger PO ± various important papers published since 1990.z CEN Report 1752, Ventilation for Buildings ± Design Criteria for the indoor environment, Dec. 1998.