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At least 163 records · Page 9Linked to original sources
PubMed1999

Germicidal ultraviolet irradiation in air conditioning systems: effect on office worker health and wellbeing: a pilot study.

OBJECTIVES: The indoor environment of modern office buildings represents a new ecosystem that has been created totally by humans. Bacteria and fungi may contaminate this indoor environment, including the ventilation systems themselves, which in turn may result in adverse health effects. The objectives of this study were to test whether installation and operation of germicidal ultraviolet (GUV) lights in central ventilation systems would be feasible, without adverse effects, undetected by building occupants, and effective in eliminating microbial contamination. METHODS: GUV lights were installed in the ventilation systems serving three floors of an office building, and were turned on and off during a total of four alternating 3 week blocks. Workers reported their environmental satisfaction, symptoms, as well as sickness absence, without knowledge of whether GUV lights were on or off. The indoor environment was measured in detail including airborne and surface bacteria and fungi. RESULTS: Airborne bacteria and fungi were not significantly different whether GUV lights were on or off, but were virtually eliminated from the surfaces of the ventilation system after 3 weeks of operation of GUV light. Of the other environmental variables measured, only total airborne particulates were significantly different under the two experimental conditions--higher with GUV lights on than off. Of 113 eligible workers, 104 (87%) participated; their environmental satisfaction ratings were not different whether GUV lights were on or off. Headache, difficulty concentrating, and eye irritation occurred less often with GUV lights on whereas skin rash or irritation was more common. Overall, the average number of work related symptoms reported was 1.1 with GUV lights off compared with 0.9 with GUV lights on. CONCLUSION: Installation and operation of GUV lights in central heating, ventilation and air conditioning systems of office buildings is feasible, cannot be detected by workers, and does not seem to result in any adverse effects.

Adult↗
PubMed2005

Disparities by race in heat-related mortality in four US cities: the role of air conditioning prevalence.

Daily mortality is typically higher on hot days in urban areas, and certain population groups experience disproportionate risk. Air conditioning (AC) has been recommended to mitigate heat-related illness and death. We examined whether AC prevalence explained differing heat-related mortality effects by race. Poisson regression was used to model daily mortality in Chicago, Detroit, Minneapolis, and Pittsburgh. Predictors included natural splines of time (to control seasonal patterns); mean daily apparent temperature on the day of death, and averaged over lags 1-3; barometric pressure; day of week; and a linear term for airborne particles. Separate, city-specific models were fit to death counts stratified by race (Black or White) to derive the percent change in mortality at 29 degrees C, relative to 15 degrees C (lag 0). Next, city-specific effects were regressed on city- and race-specific AC prevalence. Combined effect estimates across all cities were calculated using inverse variance-weighted averages. Prevalence of central AC among Black households was less than half that among White households in all four cities, and deaths among Blacks were more strongly associated with hot temperatures. Central AC prevalence explained some of the differences in heat effects by race, but room-unit AC did not. Efforts to reduce disparities in heat-related mortality should consider access to AC.

Black or African American↗
PubMed1993

Narrow-band (TL-01) UVB air-conditioned phototherapy for chronic severe adult atopic dermatitis.

In an open study of 21 severely affected adult atopic dermatitis patients, air-conditioned narrow-band UVB phototherapy using the Philips TL-01 lamp three times weekly for 12 weeks resulted in a 68% reduction in atopic dermatitis severity scores, with a concomitant 88% reduction in potent topical steroid use. Follow-up at 24 weeks revealed that six patients had relapsed to > 70% of pre-phototherapy severity scores; the remaining 15 continued to derive long-term benefit. The mean value of potent topical steroid use remained 50% below pre-phototherapy needs. Narrow-band UVB (TL-01) phototherapy appears an effective, steroid-sparing treatment for chronic severe atopic dermatitis, offering long-term benefits in the majority of those treated.

Adult↗
PubMed1978

[Wound contamination in conventionally air-conditioned operating rooms as compared to laminar-flow-operating-rooms (author's transl)].

Two operating rooms (OP K I, OP K II) with conventional air-conditioning and one operating room with horizontal laminar-flow-ventilation (TAVS) were compared by measurements of airborne microorganisms, settling microorganisms and wound contamination. In OP K I and OP K II the number of airborne colonie forming units (cfu) was about 8/m3 when the rooms were empty and between 70/m3 (OP K I) and 140/m3 (OP K II) during operations. The first air in the TAVS-OP contained less than 1 cfu/m3, downstream of the operating team up to 80 cfu/m3. The number of settling microorganisms at the wound site was about 13 cfu/100 cm2 h in OP K I and OP K II, and about 2 cfu/100 cm2 h in the TAVS OP. Wound swabs showed a contamination rate of 45% (OP K I) and 54% (OP K II) versus 31% under TAVS-conditions. The difference is statistically significant with p less than 0.05. Various other factors as e.g. the duration of exposition, traffic of persons into and out of the rooms and the fate of microorganisms after sedimentation into the wound are discussed. While the number of settling germs is growing in linear proportion to the duration of exposition, the number of wounds found contaminated does probably approach a steady state in dependence of sedimentation rate and die-off rate in the wound.

Air Conditioning↗
PubMedDate not supplied

System design and analysis of the trans-critical carbon-dioxide automotive air-conditioning system.

As an environmentally harmless and feasible alternate refrigerant, CO2 has attracted worldwide attention, especially in the area of automobile air-conditioning (AAC). The thermal property of CO2 and its trans-critical refrigeration cycle is very different from that of the traditional CFC or HCFC system. The detailed process of CO2 system thermal cycle design and optimization is described in this paper. System prototype and performance test bench were developed to analyze the performance of the CO2 AAC system.

Air Conditioning↗