The effect of air quality on sleep and cognitive performance in school children aged 10-12 years: a double-blinded, placebo-controlled, crossover trial.

OBJECTIVES: To investigate the effect of CO2 during sleep on next-morning cognitive performance in young schoolchildren, the authors performed a double-blind fully balanced crossover placebo-controlled study. MATERIAL AND METHODS: The authors included 36 children aged 10-12 years in the climate chamber. The children slept at 21°C in 6 groups each at 3 different conditions separated by 7 days in a random order. Conditions were as follows: high ventilation with CO2 at 700 ppm, high ventilation with added pure CO2 at 2000-3000 ppm, and reduced ventilation with CO2 at 2-3000 ppm and bioeffluents. Children were subjected to a digital cognitive test battery (CANTAB) in the evening prior to sleep and on the next morning after breakfast. Sleep quality was monitored with wrist actigraphs. RESULTS: There were no significant exposure effects on cognitive performance. Sleep efficiency was significantly lower at high ventilation with CO2 at 700 ppm which is considered to be a chance effect. No other effects were seen, and no relation between air quality during sleep and next-morning cognitive performance was observed in the children emitting an estimated 10 lCO2/h per child. CONCLUSIONS: No effect of CO2 during sleep was found on next day cognition. The children were awakened in the morning, and spent from 45-70 min in well-ventilated rooms before they were tested. Hence, it cannot be precluded that the children have benefitted from the good indoor air quality conditions before and during the testing period. The slightly better sleep efficiency during high CO2 concentrations might be a chance finding. Hence, replication is needed in actual bedrooms controlling for other external factors before any generalizations can be made. Int J Occup Med Environ Health. 2023;36(2):177-91.

Estimation of the in vitro eye irritating and inflammatory potential of lipopolysaccharide (LPS) and dust by using reconstituted human corneal epithelium tissue cultures.

CONTEXT: Eye irritation is a common complaint in indoor environment, but the causes have still not been identified among the multiple exposures in house environments. To identify the potential environmental factors responsible for eye irritation and study the possible mechanisms, an in vitro model for eye irritation is suggested. MATERIALS AND METHODS: In this study, reconstituted human corneal epithelium (HCE) tissue cultures were used to study the eye irritating and inflammatory potential of lipopolysaccharide (LPS) and dust. HCE tissue cultures were exposed to a range of concentrations of LPS for 6 h and dust for 24 h, respectively. After exposure, viability and secretion of interleukins (IL) IL-1ß, IL-8, and tumor necrosis factor (TNFα) were examined. Histology was used to indicate the morphological changes after dust exposure. RESULTS: Both LPS and dust affected HCE viability. There was an increased level of IL-8 after LPS exposure, while the concentrations of IL-1ß and TNFα remained unaffected. Dust exposure resulted in an elevation of both IL-1ß and IL-8, but not TNFα. Histology study showed increased vacuolization and reduced thickness after 24 h exposure to 5 mg/mL dust. DISCUSSION AND CONCLUSION: LPS and dust showed in vitro eye irritating and inflammatory potential, and cytokines/chemokines like IL-1ß and IL-8 may be involved in the mechanisms of eye irritation. The HCE tissue culture may be used as an in vitro model to study environmental exposure induced eye irritation and inflammation.

Effects of phthalates on the human corneal endothelial cell line B4G12.

Phthalates are industrial chemicals used in many cosmetics. We evaluated an in vitro model for eye irritancy testing using the human corneal endothelial cell line B4G12. Cell proliferation and toxicity were assessed after exposing to di-n-butyl phthalate (DBP), benzyl butyl phthalate (BBP), di-2-ethylhexyl phthalate (DEHP), diisodecyl phthalate (DIDP), di-n-octyl phthalate (DnOP), and di-isononyl phthalate (DINP). Gene expression and secretion of inflammatory cytokines were evaluated after exposure to DBP. Decreased cell proliferation was observed for the phthalates DBP, BBP, and DEHP, and cell toxicity was observed for DBP and BBP. Upon DBP exposure at nontoxic concentrations, a significant increased gene expression and cytokine cell secretion were observed for interleukin-1ß (IL-1ß) and IL-8, and also an increased IL-6 secretion was observed. In conclusion, the human corneal endothelial cell line B4G12 may be a potential model for inflammatory eye irritancy testing of phthalates.

No effect of TETRA hand portable transmission signals on human cognitive function and symptoms.

Current radio frequency radiation exposure guidelines rest on well-established thermal effects. However, recent research into analogue and digital transmission fields at levels covered by the exposure guidelines has indicated possible detrimental effects on human cognitive performance. To investigate this, we conducted a controlled climate chamber study of possible changes in cognitive performance in healthy volunteers exposed to transmission signals from TETRA hand portables (TETRA handsets). The trial deployed a balanced, randomized, double-blinded cross-over design. Performance on different paper-and-pencil, auditory and computer-based cognitive tasks was monitored in 53 male volunteers (mean age 36.41 years, SD 8.35) during 45-min exposure to a TETRA handset and sham control signals remotely controlled from a laboratory more than 100 km away. The main cognitive outcome was the Trail Making B (TMB) test. In addition, the participants completed a computer-based questionnaire measuring self-reported psychological and physical symptoms. No statistically significant differences (P < 0.05) between the TETRA and sham conditions were found for either TMB (estimated difference 3.8%, confidence interval (CI) -1.6% to 9.2%) or any of the remaining cognitive tasks or symptoms. In conclusion, we found no evidence that brief exposure to hand-held TETRA transmitters' affects human cognitive function or subjective symptoms.

Cognitive function and symptoms in adults and adolescents in relation to rf radiation from UMTS base stations.

There is widespread public concern about the potential adverse health effects of mobile phones in general and their associated base stations in particular. This study was designed to investigate the acute effects of radio frequency (RF) electromagnetic fields (EMF) emitted by the Universal Mobile Telecommunication System (UMTS) mobile phone base stations on human cognitive function and symptoms. Forty adolescents (15-16 years) and 40 adults (25-40 years) were exposed to four conditions: (1) sham, (2) a Continuous Wave (CW) at 2140 MHz, (3) a signal at 2140 MHz modulated as UMTS and (4) UMTS at 2140 MHz including all control features in a randomized, double blinded cross-over design. Each exposure lasted 45 min. During exposure the participants performed different cognitive tasks with the Trail Making B (TMB) test as the main outcome and completed a questionnaire measuring self reported subjective symptoms. No statistically significant differences between the UMTS and sham conditions were found for performance on TMB. For the adults, the estimated difference between UMTS and sham was -3.2% (-9.2%; 2.9%) and for the adolescents 5.5% (-1.1%; 12.2%). No significant changes were found in any of the cognitive tasks. An increase in 'headache rating' was observed when data from the adolescents and adults were combined (P = 0.027), an effect that may be due to differences at baseline. In conclusion, the primary hypothesis that UMTS radiation reduces general performance in the TMB test was not confirmed. However, we suggest that the hypothesis of subjective symptoms and EMF exposure needs further research.

The dichotomy of relative humidity on indoor air quality.

Dry and irritated mucous membranes of the eyes and airways are common symptoms reported in office-like environments. Earlier studies suggested that indoor pollutants were responsible. We have re-evaluated, by review of the literature, how low relative humidity (RH) may influence the immediately perceived indoor air quality (IAQ), including odour, and cause irritation symptoms (i.e. longer-term perceived IAQ). "Relative humidity" were searched in major databases, and combined with: air quality, cabin air, dry eyes, formaldehyde, inflammation, mucous membranes, offices, ozone, pungency, sensory irritation, particles, precorneal tear film, sick building syndrome, stuffy air, and VOCs. The impact of RH on the immediately and longer-term perceived IAQ by VOCs, ozone, and particles is complex, because both the thermodynamic condition and the emission characteristics of building materials are influenced. Epidemiological, clinical, and human exposure studies indicate that low RH plays a role in the increase of reporting eye irritation symptoms and alteration of the precorneal tear film. These effects may be exacerbated during visual display unit work. The recommendation that IAQ should be "dry and cool" may be useful for evaluation of the immediately perceived IAQ in material emission testing, but should be considered cautiously about the development of irritation symptoms in eyes and upper airways during a workday. Studies indicate that RH about 40% is better for the eyes and upper airways than levels below 30%. The optimal RH may differ for the eyes and the airways regarding desiccation of the mucous membranes.

Upper-airway inflammation in relation to dust spiked with aldehydes or glucan.

OBJECTIVES: Organic dust is associated with adverse effects on human airways. This study was done to investigate whether the addition of beta-(1,3)-D glucan or aldehydes to office dust causes enhanced inflammation in human airways. METHODS: Thirty-six volunteers were exposed randomly to clean air, office dust, dust spiked with glucan, and dust spiked with aldehydes. The three dust exposures contained between 332 and 379 microg dust/m(3). Spiking with 1 gram of dust was done with 10 milligrams of glucan or 0.1 microliters of aldehydes. Acoustic rhinometry, rhinostereometry, nasal lavage, and lung function tests were applied. RESULTS: After the exposures to dust spiked with the glucan and aldehydes, the nasal volume decreased (-1.33 and -1.39 cm(3) (mean), respectively) when compared with the -0.9 cm(3) after clean air or office dust (P=0.036 for a difference in decrease between exposures). After 2-3 hours the aldehyde-spiked dust caused a 0.6-mm swelling of the inferior turbinate, and glucan-spiked dust produced a 0.7-mm swelling (P=0.039 for a difference in the swelling between the four exposures). The preexposure nasal lavage cleaned off the mucosa, and lower cytokine concentrations were found after all of the exposures. For interleukin-8, this decrease in concentration was smaller after the dust exposures spiked with glucan and aldehydes (-2.9 and -25.8 pg/ml, respectively) than after office dust or clean air (-65.9 and -74.1 pg/ml, respectively) (P=0.042). The nasal eosinophil cell concentration increased after exposure to dust spiked with glucan (P=0.045). CONCLUSIONS: beta-(1,3)-D glucan and aldehydes in office dust enhance the inflammatory effects of dust on the upper airways.

A chamber-experiment investigation of the interaction between perceptions of noise and odor in humans.

OBJECTIVES: This study was designed to investigate human comfort and health effects following exposure to noise and odor and to explore the interaction between perceptions of noise and odor in humans. MATERIALS AND METHODS: Nine healthy subjects were randomly exposed to noise, odor, and their combination, in a 3 x 3 Latin square design for 80 min in an exposure chamber. Continuous noise was broadcast at an average level of 75 dBA by a loudspeaker, and odor was provided by furfurylmercaptan (a coffee-aroma constituent). A standardized 28-item questionnaire, together with mood-scale ratings, nasal dimensions by acoustic rhinometry, addition tests for distraction, and skin humidity, were performed before and at the end of exposure. RESULTS: In the questionnaire investigation, the perceived "sound level" was significantly affected by noise and the combined exposures, while "odor intensity", "air quality", and "need more ventilation" was significantly affected by odor and the combined exposures. Perceptions of symptoms became worse with increasing exposure time, such as perceived "dry nose" and "sleepiness" by odor and combined exposures, "headache" by noise, "concentration difficulty", "general well being", and "stressed by being in the chamber" by noise, odor and combined exposures. In addition, the occurrence of interactions was analyzed by comparison of the ratings of perceived "sound level", "odor intensity", "air quality", and "need more ventilation" during the combined exposure with two single exposures. Insignificant interaction was found but it indicated a decreased tendency to perceptions of discomfort from "odor intensity", "air quality", and "need for more ventilation" when noise was added to odor exposure. CONCLUSION: It may be concluded that noise and odor cause discomfort in humans. Moreover, the study might indicate that additions of noise reduce (mask) the perception of discomfort from odor, and additions of odor have no or little affect on the perception of noise.