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At least 289 records · Page 16Linked to original sources
PubMed2005

Global food insecurity. treatment of major food crops with elevated carbon dioxide or ozone under large-scale fully open-air conditions suggests recent models may have overestimated future yields.

Predictions of yield for the globe's major grain and legume arable crops suggest that, with a moderate temperature increase, production may increase in the temperate zone, but decline in the tropics. In total, global food supply may show little change. This security comes from inclusion of the direct effect of rising carbon dioxide (CO2) concentration, [CO2], which significantly stimulates yield by decreasing photorespiration in C3 crops and transpiration in all crops. Evidence for a large response to [CO2] is largely based on studies made within chambers at small scales, which would be considered unacceptable for standard agronomic trials of new cultivars or agrochemicals. Yet, predictions of the globe's future food security are based on such inadequate information. Free-Air Concentration Enrichment (FACE) technology now allows investigation of the effects of rising [CO2] and ozone on field crops under fully open-air conditions at an agronomic scale. Experiments with rice, wheat, maize and soybean show smaller increases in yield than anticipated from studies in chambers. Experiments with increased ozone show large yield losses (20%), which are not accounted for in projections of global food security. These findings suggest that current projections of global food security are overoptimistic. The fertilization effect of CO2 is less than that used in many models, while rising ozone will cause large yield losses in the Northern Hemisphere. Unfortunately, FACE studies have been limited in geographical extent and interactive effects of CO2, ozone and temperature have yet to be studied. Without more extensive study of the effects of these changes at an agronomic scale in the open air, our ever-more sophisticated models will continue to have feet of clay.

Acclimatization↗
PubMed2004

The influence of air conditioning, humidity, temperature and other household characteristics on mite allergen concentrations in the northeastern United States.

BACKGROUND: Information about the influence of housing and occupant characteristics on mite allergen concentrations is crucial to determine which methods could be used to decrease exposure of susceptible subjects. OBJECTIVES: To identify housing and occupant characteristics that are associated with mite allergen concentrations in house dust collected from living rooms and mattresses. METHODS: We collected dust samples from 750 homes in the northeastern US. The influence of various characteristics on concentrations of mite allergens (Der p 1 and Der f 1) was studied using multiple linear regression analysis. RESULTS: Some characteristics, like absence of air conditioners, the presence of mold or mildew, and a lower temperature were consistently associated with higher concentrations of both mite allergens in dust from all sampling locations. However, none of these factors changed Der p 1 or Der f 1 concentrations by more than a factor of 2. People of white ethnic background had roughly two times higher mite allergen concentrations, while family income, family size, and education level only marginally influenced mite allergen concentrations. CONCLUSIONS: Various housing characteristics have some influence on mite allergen concentrations, and could possibly be used to decrease exposure of susceptible subjects. However, only a limited percentage of the variation in mite allergen concentrations was explained by these characteristics.

Air Conditioning↗
PubMed1987

Exposure to fluorocarbons during the filling and repair of air-conditioning systems in cars--a case report.

A worker exposed to fluorocarbons in an automobile plant for seven years experienced shortness of breath (in 1977) and was referred to the hospital. The clinical examination revealed electrocardiographic abnormalities. He recovered quickly and returned to work. During the following year (1978) he suffered subarachnoid bleeding with hemiparesis, and four years later he had an operation for a thymoma. Hygienic measurements in 1980-1981 showed large variations in the fluorocarbon concentrations in the plant, the average 8-h concentrations being below the occupational exposure limit of 500 ppm but several short-time measurements reaching levels of over 750 ppm. It was suggested that, persons with heart disease do not necessarily have to be removed from work with fluorocarbons without careful review of the exposure but that the evaluation of the exposure should not only be based on time-weighted average concentrations, but also on values for brief periods, in that such concentrations can often be decreased by simple and cheap measures.

Air Conditioning↗
PubMed1989

[The air conditioning system in locomotive compartments].

Development of the devices for the improvement of air chemical content of cabs, disposal of noxious aerosols and light aeroionic separation is one of the most urgent problems of optimization and sanitation of working conditions of locomotive engine-drivers. Sectoral laboratory of atmospheric air protection of the Ministry for Ways of Communication of the USSR developed a highly effective system of air purification and conditioning in locomotive's cabs. The system involved a draught agitator, devices of air electric heating, electrostatic air treatment, humidification and neutralization. The system ensured cabin's air recirculation 6 times per hour. Besides necessary air heating and humidification, air dustiness and microbic contamination decreased to 0.2 mg/m3 and about 100 colonies per m3, respectively. The level of air saturation by light aeroions increased from 500 to 1200 per cm3. At the system outlet there were no nitrogen and ozone oxides. The design of the system was covered by patent.

Air Conditioning↗