SEARCH · PubMed Health

Results for “Humidity”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 937 records · Page 52Linked to original sources

PubMed2005

[Wall relative humidity: a simple and reliable index for predicting Stachybotrys chartarum infestation in dwellings].

As the indoor mold Stachybotrys chartarum (SC) has been linked to serious health disorders, its identification in water-damaged dwellings is of utmost importance. The aim of this work was to compare wall relative humidity (RH) measurements with the results of mold identification studied on 458 samples collected from 100 dwellings. Mold identification was based on direct microscopic examination of wall samples collected by the gummed paper technique. Mean (+/- SD) wall RH (%) was much higher (97.0 +/- 6.1) when SC was identified (30 samples) than when other molds were identified (291 samples, 41.8 +/- 36.9) and when no molds were identified (137 samples, 38.9 +/- 34.8). There was a direct relationship between wall and room-air RH but the scatter of results implies that the latter cannot be used as a surrogate for the former. This study suggests that simple wall RH measurement can serve as a reliable indicator of SC infestation of dwellings.

Air Pollution, Indoor↗

PubMed2006

Enhancement of virus-induced gene silencing in tomato by low temperature and low humidity.

Virus-induced gene silencing (VIGS) is an attractive reverse-genetics tool for studying gene function in plants. We showed that silencing of a phytoene desaturase (PDS) gene is maintained throughout TRV-PDS-inoculated tomato plants as well as in their flowers and fruit and is enhanced by low temperature (15 degrees C) and low humidity (30%). RT-PCR analysis of the PDS gene revealed a dramatic reduction in the level of PDS mRNA in leaves, flowers and fruits. Silencing of PDS results in the accumulation of phytoene, the desaturase substrate. In addition, the content of chlorophyll a, chlorophyll b and total chlorophyll in the leaves of PDS-silenced plants was reduced by more than 90%. We also silenced the LeEIN2 gene by infecting seedlings, and this suppressed fruit ripenning. We conclude that this VIGS approach should facilitate large-scale functional analysis of genes involved in the development and ripening of tomato.

Carotenoids↗

PubMed1991

Humidity-dependent structural changes in native collagen studied by X-ray diffractometry.

1. X-ray diffractometry was used in this work to study structural modifications of powdered native collagen submitted to repeated cycles of gradual drying and hydration. 2. Hysteresis effects known to exist in water sorption isotherms of this fibrous protein were detected in the plots of relative humidity vs integrated intensity of the wide angle X-ray reflections which constitute the main features of the diffraction pattern. 3. A gradual loss of structured material was observed after each drying and rehydration process. An increase in the amorphous regions of the fibrils could also be inferred from the diffraction data. 4. Drying the samples up to a critical degree of hydration (0.12 g H2O per g protein) did not produce a hysteresis loop in the plots of the parameters studied. 5. One-step drying-rehydration cycles did not seem to affect the order of the samples since they repeatedly recovered their original structure. The difference between these results and those of the gradual hydration processes may be attributed to the kinetic properties of biopolymer hydration. The rate of water removal seems to be an important factor in the structural modifications produced by the hydration (dehydration) process.

Collagen↗

PubMed1991

Formaldehyde release from furnishing fabrics. Effect of ageing, temperature and air humidity.

The contamination of indoor air by formaldehyde (CH2O) is a serious hygienic problem. One of the potential sources of formaldehyde release may be furnishing fabrics. The study was conducted to evaluate the effect of ageing on textiles (17.5 months), air temperature (25-45 degrees C) and relative air humidity (RH) (45-85%) on the CH2O release rate from 6 kinds of drapers and furniture coverings. The emission was determined in small glass chambers (13.08 dm3) under controlled conditions: at one air exchange per hour and load factor 1 m2/m3. Results of these studies indicated that effect of textile ageing on CH2O emission was different for each fabric tested. The increase of temperature and RH within the ranges studied multiplied the rate of CH2O release. The drapers and covering fabrics tested, in the production of which textile dressing containing CH2O compounds was used, may remain a source of formaldehyde emission for several months.

Air Pollution, Indoor↗

PubMed1990

[Meteorologic effects on hemorrhagic diathesis in hemophilia. 2. Weather effects on hemophilia with special reference to the atmospheric temperature-humidity complex].

The meteotropism of haemophilic haemorrhages was investigated for 1,802 episodes of bleeding in 223 patients with the help of selected parameters of the atmospheric temperature-humidity complex and the air pressure. The accumulation of haemorrhages under the influence of tropic air masses was particularly conspicuous. In low blood pressure the frequency of bleeding also increased, whereas high-pressure conditions showed a decrease of bleeding. The study clearly confirms that the haemorrhagic tendency in haemophilia is influenced by weather. Therefore a medico-meteorologic forecast should be taken into consideration for haemophiliacs.

Atmospheric Pressure↗

PubMedDate not supplied

Optimal time for vaccination against Peste des petits ruminants (PPR) disease in goats in humid tropical zone in southern Nigeria.

Investigation of the incidence of peste des petits ruminants (PPR) disease in goats revealed seasonality in the natural occurrence of PPR disease in the environment. Tissue culture rinderpest vaccine was shown effective in protecting goats against the disease. The optimal time for vaccinating goats against PPR disease was when the least number of animals were incubating the disease. In the tropical humid zone, as in West Africa, the optimal time for vaccination against the PPR disease is from late November to middle of December.

Animals↗

PubMed1990

Heat stress in dairy cattle under southern African conditions. II. Identification of areas of potential heat stress during summer by means of observed true and predicted temperature-humidity index values.

November-March are the hottest months of the year with the highest monthly mean "temperature-humidity index" (THI) in South Africa and Namibia. These 5 months are associated with severe heat stress in dairy cattle, are of critical importance for their performance and may have great economic implications for the owner as well as for the dairy industry. Firstly, compared with the existing Livestock Weather Safety index (LWSI), more relevant meteorological data can be generated when mapping South Africa and Namibia according to the LWSI modified for lactating dairy cattle (LDC). Secondly, compared with the observed true THI values alone, more relevant data on heat stress and its deleterious effects on dairy cattle performance, become available when mapping South Africa and Namibia according to the combined observed true and predicted THI values. Minimum precautions against heat stress in dairy cattle are recommended depending on THI values as classified by the LWSI for LDC.

Animals↗

PubMed1990

Heat stress in dairy cattle and other livestock under southern African conditions. III. Monthly temperature-humidity index mean values and their significance in the performance of dairy cattle.

Temperature-humidity index (THI) values applicable to South Africa and Namibia have been established during this investigation for each month of the year by means of computerized modelling and mapping techniques. The data indicate that each year heat stress risk areas (HSRA's) expand from August to January and retract from February to July. The THI values classified according to the Livestock Weather Safety Index (LWSI) for lactating dairy cattle (LDC), suggest that, especially during November to March there is the risk of moderate to advanced heat stress in most South African dairy cows. This has important implications for their general health, udder health, production and reproduction. Careful planning of facilities and highly adaptable herd management are required to protect dairy cattle from heat stress.

Animals↗

PubMed1990

Heat stress in dairy cattle and other livestock under southern African conditions. I. Temperature-humidity index mean values during the four main seasons.

The Livestock Weather Safety Index (LWSI) indicates that in large areas of South Africa and South West Africa/Namibia and for prolonged periods of the year warm conditions are causing heat stress in food-producing animals, especially dairy cattle, thereby hampering their performance. South Africa and South West Africa/Namibia have been mapped according to a modified LWSI, which includes the critical "temperature-humidity index" value for milk production. The importance of heat stress in dairy cattle is discussed relative to such areas.

Animals↗

PubMed1989

Disinfection with gaseous formaldehyde. Third Part: Bactericidal and sporicidal effectiveness of gaseous formaldehyde and level of residues in dependence on concentration, temperature and relative humidity.

The highest rate of inactivation of Staphylococcus aureus (ATCC 6538), Streptococcus faecium (ATCC 6057) and spores of Bacillus subtilis var. niger (DSM 675) was observed at a relative humidity (RH) of 90-95%. At a RH of 60% D 0.75 mg HCHO l-1 air at 45 degrees C-values of 35 min and over 65 min were determined for S. aureus and for B. subtilis spores which decreased to D = 2.9 min and D = 20 min respectively at a RH of 90%. At 45 degrees C, an optimal formaldehyde (HCHO) concentration for the inactivation of S. aureus was within the range of 0.75 to 1.5 mg HCHO l-1 air, with D-values of 2.9 to 1.8 min respectively and for Bacillus subtilis spores from 1.5 to 3.2 mg HCHO l-1 air with D-values of 10.9 to 4.0 min respectively. The most effective bactericidal and sporicidal activity of HCHO was observed at temperatures ranging from 40 to 45 degrees C. The higher the exposure temperature the lower were the HCHO residues on 100 cm2 aluminium plates with a structured lacquer. Exposure to formaldehyde concentrations of 0.4 mg l-1 air for 60 minutes resulted in lower residual formaldehyde of 5.9, 5.6, 4.7 and 4.5 micrograms HCHO 100 cm-2 sample surface at 30, 35, 40 and 45 degrees C, respectively. In contrast, after exposures to 3.2 mg HCHO l-1 air residues of 48.5, 43.4, 35.6 and 30.6 micrograms HCHO 100 cm-2 were found at the same temperatures.

Bacillus subtilis↗

PubMed1989

Evaluation of deoxyribonucleic acid (DNA) isolated from human bloodstains exposed to ultraviolet light, heat, humidity, and soil contamination.

This study was designed to analyze the effects of common environmental insults on the ability to obtain deoxyribonucleic acid (DNA) restriction fragment-length polymorphisms (RFLP) patterns from laboratory prepared specimens. The environmental conditions studied include the exposure of dried bloodstains to varying amounts of relative humidity (0, 33, 67, and 98%), heat (37 degrees C), and ultraviolet light for periods of up to five days. In addition, the effect of drying over a four-day period in whole blood collected with and without ethylenediaminetetraacetate (EDTA) was examined. The results of the study showed that, under the conditions studied, the integrity of DNA is not altered such that false RFLP patterns are obtained. The only effect observed was that the overall RFLP pattern becomes weaker, but individual RFLP fragments are neither created nor destroyed.

Blood Stains↗

PubMed1989

[Effect of chemical structure of various penicillins on the stability of beta-lactam group in their molecules. VI. Effects of relative humidity and heat on the stability of amoxicillin trihydrate and amoxicillin sodium in the solid phase].

Dependence of stability of Amoxycillin trihydrate (AMOXY. 3H2O) and Amoxycillin-Natrium (AMOXY-Na) upon relative humidity (RH) and temperature was investigated using the iodometric method for the determination of Amoxycillin. The first order rate constants and activation parameters have been determined at controlled moisture conditions. The straightline relationship lg k = f(RH) at T = const. has been stated, which however is fulfilled by AMOXY-Na only at RH greater than or equal to 50%. The calculated factors of the equation lg k = a + b.1/T + c.RH proved to enable estimation of the stability of the studied antibiotics at any climate conditions. The performed kinetic studies have shown that AMOXY-Na undergoes degradation about 1.5 x 10(3) times faster than AMOXY.3H2O, at RH greater than or equal to 50%.

Amoxicillin↗

PubMed1989

[Comparison of 2 exchangers of heat and humidity in anesthesia (Hygrobac vs Ultipor BB50)].

Comparison between Hygrobac and Ultipor BB50, two commercially available heat and moisture exchangers, shows that the former is more efficient: temperature (T degrees C) and water content (absolute humidity, AH) of the inspired gas is greater with Hygrobac than Ultipor BB50. However, both HMEs work at the low limit of the normally accepted range of T degrees C and AH for intubated patients.

Anesthesiology↗

PubMed1977

[Comparative studies on the setting time of various phosphate cements and on the effect of differentiated powder-fluid ratios and air humidity on the setting time].

A comparative experimental study served to determine the standard consistency and setting time of various phosphate cements (according to DIN 13903). One of the products under investigation did not comply with standard specifications; therefore, from the viewpoint of setting behaviour, it cannot be recommended for cementing fixed tooth-restorations. It was shown that variations in the powder-liquid ratio affected the setting time, whereas variations in air humidity in the range from 50 to 100% exerted no signficant effects, which might lead to a simplication of material testing and quality control.

Humidity↗

PubMed1978

[Effect of oxygen and humidity on UV-polymerizable sealing materials].

The influence of humidity, oxygen and protecting gases on the wetting capacity of UV polymerisable adhesives is examined by means of border-angle measurements. The thickness of the upper layer not polymerisable through the presence of oxygen is determined and its effect on the surface structure of compounds is clarified by scanning electron microsc-investigations. For solution the use of a protecting gas is discussed.

Bicuspid↗

PubMed1986

Lung function and bronchial hyperreactivity following exposure to four different temperatures and relative humidities.

Seven asthmatic patients were exposed to four different climatic conditions in a climate chamber. The four conditions were: 15 degrees C/30% relative humidity (RH), 15 degrees C/70% RH, 30 degrees C/30% RH and 30 degrees C/70% RH and the exposure time was 4 hours. Before and after the exposure the following lung function parameters were measured: PEF, FEV1, RV and TLC. After each exposure a bronchial challenge with histamine was performed by the doubling-dose principle. The results indicated no difference in lung function after exposure to the "extreme" conditions in this study (i.e. 15 degrees C/30% RH and 30 degrees C/70% RH, water content 3.5 and 19 g/kg dry air, respectively), while a decrease in RV and TLC was seen after exposure to the "middle" conditions (i.e. 15 degrees C/70% RH and 30 degrees C/30% RH, water content 7.5 and 8 g/kg dry air, respectively). No change in ventilatory capacity was seen, and the bronchial hyperactivity also remained unchanged. During the 4 hours exposure, measurements of FEV1 and PEF also remained constant. It is concluded that this kind of exposure is without great effect on the asthmatics condition.

Adult↗

PubMed1985

The effects of temperature, relative humidity and host factors on the attachment and survival of Boophilus decoloratus and Boophilus geigyi larvae to skin slices.

Attachment and survival of Boophilus decoloratus and B. geigyi larvae were examined using skin slices from cattle, sheep and goats. Results indicate that B. decoloratus has a wider range of temperature (24-40 degrees C) at which more than 50% of larvae would attach to bovine skin, while B. geigyi has a narrower range (24-30 degrees C). The larvae of both species had two peaks of attachment--the 4th and 20th hour, the value for the second peak being greater than the first. The influence of humidity on larval attachment was only apparent where the temperature was high, and in such cases more than 70% of B. decoloratus larvae attached, while less than 20% of B. geigyi larvae attached by the 20th hour. Less than 50% of larval attachment was recorded on both sheep and goats. The results are related to the geographical distribution of both species in Nigeria, and to the problems of tick water balance, stimuli for tick attachment and host specificity.

Animals↗

PubMed1982

Production and utilization of extracellular slime by Pseudomonas solanacearum and its role on survival at different relative humidities.

Pseudomonas solanacearum produced maximum slime with glucose and least with glycerol. With increasing concentration of glucose, slime production increased. The maximum slime production was observed in the medium containing 1% glucose. The slime contained sugars, sugar acids and amino acids. The bacterium utilized the slime as a sole source of carbon. The growth on slime was more or less comparable to the growth on 0.1% glucose. The viability of the bacterium in slime increased as the relative humidity (RH) decreased. At higher RH the slime absorbed moisture and the viability was reduced. The bacterium could survive only for short period at higher RH under sunlight not in shade. The sunlight seemed to accentuate the harmful effect of RH on the bacterium.

Glucose↗