Snow has already been used effectively as a cold energy resource in some heavy snowfall areasin Japan. As the surface of snow is covered with cold melting water when snow is used as a coldenergy resource, we can expect gas absorption on the surface. By this mechanism of the gasabsorption, some airborne contaminants such as dust or harmful gases can be removed by themelting snow surface.

Emissions from dust collected in air filters have been investigated using in situ and chambermeasurements. Two air filters (class F6 and F8/9) were exposed to outdoor air for a period ofsix months, after which measurements were carried out during continuous and intermittentoperation. Air samples were taken upstream and downstream of the filters and analysed forseveral substances, including VOCS, formaldehyde, microbial VOCS (MVOC), vital microorganisms,ergosterol and endotoxin.

As part of an ongoing investigation on service life of air filtration material, a new type of airfiltration material (multi-layered polymer) was compared with a widely used material todetermine growth or survival of micro-organisms after normal dust loading. Blinding wasperformed by the manufacturer supplying the materials as anonymous A and B. Microorganismswere extracted after 2, 4, 6, and 8 weeks by washing (shake out) and plating thesolution onto agar media, incubated and differentiated. Vital fluorescence microscopy wasalso performed. The results showed a significant difference (P

Indoor and outdoor particle concentrations and ventilation rates were measured versus time ina large office building without tobacco smoking. Periodically, high efficiency filters replacedthe normal filters in air handling systems. For all particle sizes, indoor concentrations variedconsiderably with time. Even with the normal air filters, which have a low efficiency forsubmicron particles, number concentrations of submicron particles were a factor of three tosix smaller indoors compared to outdoors.

Formaldehyde (FA) adsorption, including that in the presence of water vapours, has been evaluated on adsorbents of various nature and porous structure. The efficiency of porous adsorbents (active carbons, silica-gels) with a pore size of 2-200 nm, providing rapid adsorption of low FA concentrations from dry air and a high sorption from the FA water mixture, has been demonstrated. Recommendations on the practical use of adsorbents for indoor purification have been given.

The role of indoor plants as a source of microorganisms was studied in six office rooms.Concentrations of microorganisms (both fungi and actinomycetes) were determined fromindoor air and settled dust before the plants were placed in the office rooms and afterwardswith the plants in the rooms.

Indoor air quality is decreasing year by year. It is very necessary to find a kind of efficient cleaner to improve the indoor air quality. Two kinds of cleaners were tested. Both of them were made in China. Four simulated chambers were used. The research was performed with monitoring and toxicological tests. The results showed the cleaner A absorbed and filtered smoke very fast. But CO and CH2O could not have been absorbed and filtered. Cleaner B either could absorb smoke or could exchange air with outdoor air. The cleaning efficiency of cleaner B is better than that of cleaner B.

Photocatalytic degradation of volatile organic compounds (VOC) with short-wavelength UVlight (254 nm) is an attractive technique in the view of perfect mineralization to CO2. In thisstudy, shorter wavelength of UV light involving 185 nm which generates O3 was used as a lightsource, and as a photocatalyst, titanium dioxide (TiO2) and its mixture with ozonedecomposition catalyst (ODC) was tested to improve photocatalytic activity. Their validity wasevaluated from the removal ratio of toluene by photocatalysis and the size distribution ofgenerated particles by gas-to-particle conversion.

This study is part of an investigation of the decontamination capabilities of indoor plants.Three internationally used species, Howea forsteriana Becc. (Kentia Palm), Dracaenaderemensis Eng. Janet Craig, and Spathiphyllum Petite (Peace Lily), were evaluated for theability to reduce or remove benzene and n-hexane from indoor air. Plants tested in bothpotting media and hydroponic conditions removed the individual VOCs at concentrationsequal to 2 and 5 times the maximum occupational exposure levels recommended by theWorksafe Australia Time-weighted average exposure standard (TWA), [1].

The goal of this study was to investigate the effectiveness of stand-alone modular airpurification systems in improving air quality in dental practices and certain hospital andlaboratory environments. As air pollutant make-up and concentration may vary significantlyin different indoor enviromnents, the air cleaning technologies utilised should be optimisedfor the pollutants targeted in a particular environment. Reduction of mercury vapours andformaldehyde were examined because of their importance for indoor air quality in dentalpractices.