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Differential effects of air conditioning type on residential endotoxin levels in a semi‐arid climate
Author(s) -
Johnston J. D.,
Kruman B. A.,
Nelson M. C.,
Merrill R. M.,
Graul R. J.,
Hoybjerg T. G.,
Tuttle S. C.,
Myers S. J.,
Cook R. B.,
Weber K. S.
Publication year - 2017
Publication title -
indoor air
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.387
H-Index - 99
eISSN - 1600-0668
pISSN - 0905-6947
DOI - 10.1111/ina.12369
Subject(s) - bedroom , evaporative cooler , environmental science , air conditioning , relative humidity , limulus amebocyte lysate , atmospheric sciences , humidity , environmental engineering , hydrology (agriculture) , meteorology , geography , engineering , biology , mechanical engineering , geotechnical engineering , archaeology , endocrinology , lipopolysaccharide , geology
Residential endotoxin exposure is associated with protective and pathogenic health outcomes. Evaporative coolers, an energy‐efficient type of air conditioner used in dry climates, are a potential source of indoor endotoxins; however, this association is largely unstudied. We collected settled dust biannually from four locations in homes with evaporative coolers (n=18) and central air conditioners (n=22) in Utah County, Utah ( USA ), during winter (Jan‐Apr) and summer (Aug‐Sept), 2014. Dust samples (n=281) were analyzed by the Limulus amebocyte lysate test. Housing factors were measured by survey, and indoor temperature and relative humidity measures were collected during both seasons. Endotoxin concentrations ( EU /mg) were significantly higher in homes with evaporative coolers from mattress and bedroom floor samples during both seasons. Endotoxin surface loads ( EU /m 2 ) were significantly higher in homes with evaporative coolers from mattress and bedroom floor samples during both seasons and in upholstered furniture during winter. For the nine significant season‐by‐location comparisons, EU /mg and EU /m 2 were approximately three to six times greater in homes using evaporative coolers. A plausible explanation for these findings is that evaporative coolers serve as a reservoir and distribution system for Gram‐negative bacteria or their cell wall components in homes.