Indoor aerosol, generation

Choose an aerosol generator according to where you will use it—indoors or outdoors. Aerosol and fog generators are manufactured for many special uses. There are tmck- and trailer-mounted machines for use outdoors. Most hand-operated or permanently mounted automatic machines are for use indoors. 

Sihcone contamination has been impHcated as a cause of failure in telephone switching systems and other devices that contain relay switch contacts (507). Analysis of airborne particulates near telephone switching stations showed the presence of siUcones at these locations. Where the indoor use of sihcones is intentionally minimised, outdoor levels were found to be higher than inside concentrations (508). Samples of particulates taken at two New Jersey office buildings revealed sihcone levels that were considerably higher indoors than outdoors. In these cases, indoor sihcone aerosols are beheved to be generated primarily by photocopiers, which use sihcone fuser oils. 

For volume production of an aerosol fog of small particle size, on a large scale (suited to indoor use), the thermal aerosol fog generators appear to be very efficient. The Science Service experiments were mostly with this type. Two principal varieties have been developed. One discharges the insecticide solution or suspension as a relatively coarse spray into a jet of superheated steam delivered by a flash boiler of the tubular coil t3rpe. The other discharges that insecticide solution or suspension as a relatively coarse spray into a blast of hot gas emerging from a combustion chamber. The temperature is regulated by the controlled admixture of cold air. 

Indoor Chemistry Various terpenes and terpenoids are emitted from household products and building materials. Ozone that has entered from outdoors or has been generated indoors can react with these compounds, either in the gas phase or on the surface of materials. The resulting oxidation products will contribute to the production and growth of meaningful quantities of secondary organic aerosols (SOA). The formation and growth of SOA can be studied under controlled conditions in test chambers (see also Chapter 13). 

Found in cigarette mainstream smoke. D-limonene may be released to the environment as a fugitive emission during its production, use, or transport. Limonene has been measured in open burning emissions, and studies have shown that gas phase reactions between ozone and terpenes can be a significant source of secondary organic aerosols. The simultaneous occurrence of ozone and terpenes in an indoor environment is relatively common. Ozone is routinely transported from outdoors to indoors, and indoor sources include photocopiers, electrostatic precipitators, and ozone generators. Limonene has been found as a contaminant in washed and dried shredded polyethylene terephthalate (PET, flake) obtained from curbside collection. 

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