The effects of bedroom air quality on sleep and next-day performance.

The effects of bedroom air quality on sleep and next-day performance were examined in two field-intervention experiments in single-occupancy student dormitory rooms. The occupants, half of them women, could adjust an electric heater to maintain thermal comfort but they experienced two bedroom ventilation conditions, each maintained for 1 week, in balanced order. In the initial pilot experiment (N = 14), bedroom ventilation was changed by opening a window (the resulting average CO2 level was 2585 or 660 ppm). In the second experiment (N = 16), an inaudible fan in the air intake vent was either disabled or operated whenever CO2 levels exceeded 900 ppm (the resulting average CO2 level was 2395 or 835 ppm). Bedroom air temperatures varied over a wide range but did not differ between ventilation conditions. Sleep was assessed from movement data recorded on wristwatch-type actigraphs and subjects reported their perceptions and their well-being each morning using online questionnaires. Two tests of next-day mental performance were applied. Objectively measured sleep quality and the perceived freshness of bedroom air improved significantly when the CO2 level was lower, as did next-day reported sleepiness and ability to concentrate and the subjects' performance of a test of logical thinking.

Experimental hypothyroidism increases content of collagen and glycosaminoglycans in the heart.

The connective tissue matrix of the heart remains under regulatory influence of the thyroid hormones. Some conflicting data describe the connective tissue changes in subjects with thyroid gland disorders. The aim of the study was to assess the changes of the connective tissue accumulation in the heart of rats in the state of hypothyroidism and to answer the question whether TSH is involved in mechanism of the observed phenomena. Hypothyroidism in rats was induced by methylotiouracil treatment or by thyreoidectomy. The thyroid hormones [freeT3 (fT3), freeT4 (fT4)] and pituitary TSH were measured in plasma with radioimmunological method. The glycosaminoglycans (GAG) and total collagen were measured in heart muscle of both left and right ventricles. Cells from the rat's heart were isolated and cultured. The cells were identified as myofibroblasts by electron microscopy method. The effects of TSH in concentrations ranging from 0.002 to 20 mIU/ml, on connective tissue accumulation in heart myofibroblasts cultures were tested. The primary hypothyroidism was developed both in groups with thyroidectomy and with methylthiouracil. The levels of fT3 and fT4 both in rats with thyreoidectomy and animals treated with methylthiouracil were decreased and TSH level in these two experimental groups was elevated. In the heart of the rats with experimental hypothyroidism increased content of both GAG and collagen was found. Myofibroblast number in culture was increased by TSH. Regardless of the method of its induction, hypothyroidism increased collagen and GAG contents in the heart. TSH is not involved in regulation of collagen and glycosaminoglycans accumulation in the heart of rats affected with primary hypothyroidism.

Advantages for passengers and cabin crew of operating a gas-phase adsorption air purifier in 11-h simulated flights.

UNLABELLED: Experiments were carried out in a three-row, 21-seat section of a simulated aircraft cabin installed in a climate chamber to evaluate the extent to which passengers' perception of cabin air quality is affected by the operation of a gas-phase adsorption (GPA) purification unit. A total of 68 subjects, divided into four groups of 17 subjects took part in simulated 11-h flights. Each group experienced four conditions in balanced order, defined by two outside air supply rates (2.4 and 3.3 l/s per person), with and without the GPA purification unit installed in the recirculated air system, a total of 2992 subject-hours of exposure. During each flight the subjects completed questionnaires five times to provide subjective assessments of air quality, cabin environment, intensity of symptoms, and thermal comfort. Additionally, the subjects' visual acuity, finger temperature, skin dryness, and nasal peak flow were measured three times during each flight. Analysis of the subjective assessments showed that operating a GPA unit in the recirculated air provided consistent advantages with no apparent disadvantages. PRACTICAL IMPLICATIONS: Operating a gas-phase adsorption (GPA) air purifier unit in the recirculated air in a simulated airplane cabin provided a clear and consistent advantage for passengers and crew that became increasingly apparent at longer flight times. This finding indicates that the expense of undertaking duly blinded field trials on revenue flights would be justified.