Acute effects of exposure to vapors of 3-methyl-1-butanol in humans.

UNLABELLED: The secondary alcohol 3-methyl-1-butanol (3MB, isoamyl alcohol) is used, for example, as a solvent in a variety of applications and as a fragrance ingredient. It is also one of the microbial volatile organic compounds (MVOCs) found in indoor air. There are little data on acute effects. The aim of the study was to assess the acute effects of 3MB in humans. Thirty healthy volunteers (16 men and 14 women) were exposed in random order to 1 mg/m(3) 3MB or clean air for 2 h at controlled conditions. Ratings with visual analogue scales revealed slightly increased perceptions of eye irritation (P = 0.048, Wilcoxon) and smell (P < 0.0001) compared with control exposure. The other ratings were not significantly affected (irritation in nose and throat, dyspnea, headache, fatigue, dizziness, nausea, and intoxication). No significant exposure-related effects were found in blinking frequency, tear film break-up time, vital staining of the eye, nasal lavage biomarkers, lung function, and nasal swelling. In conclusion, this study suggests that 3MB is not a causative factor for health effects in damp and moldy buildings. PRACTICAL IMPLICATIONS: 3-Methyl-1-butanol (3MB) is one of the most commonly reported MVOCs in damp and moldy buildings and in occupational settings related to agriculture and composting. Our study revealed no irritation effects at 1 mg/m3, a concentration higher than typically found in damp and moldy buildings. Our study thus suggests that 3MB is not a causative factor for health effects in damp and moldy buildings.

Comparing mixing and displacement ventilation in classrooms: pupils' perception and health.

UNLABELLED: Several studies have found that indoor air quality (IAQ) in schools is often poor and may affect the health of the pupils. Building ventilation is a means to reduce pollutants indoors, but different designs should be evaluated for their effectiveness in different environments. In a field experiment performed at four classrooms in one school building, air was supplied either in the mixing or in the displacement mode, and we collected information on exposures, pupils' perception of IAQ and climate, and health symptoms and performed clinical examinations. The room temperature, relative humidity, concentration of CO2, and cat allergen were measured at the breathing height and were similar during each ventilation mode. The children perceived IAQ were similar in the two ventilation regimes, and there were few differences in symptom reports or clinical parameters. However, the pupils reported more eye symptoms during displacement ventilation. PRACTICAL IMPLICATIONS: Both mixing and displacement ventilation may be appropriate in school classrooms as long as the overall design, ventilation rates, and maintenance of systems are satisfactory.

Acute effects of exposure to 1 mg/m(3) of vaporized 2-ethyl-1-hexanol in humans.

The objective was to assess acute effects from controlled exposure of volunteers to 2-ethyl-1-hexanol, a volatile organic compound that is often found in indoor air. Sixteen males and fourteen females were in random order exposed to 1 mg/m(3) of vapors of 2-ethyl-1-hexanol or to clean air (control exposure) in an exposure chamber during 2 h at rest. The subjects performed symptom ratings on Visual Analog Scales. During exposure to 2-ethyl-1-hexanol subjective ratings of smell and eye discomfort were minimally but significantly increased. Ratings of nasal irritation, throat irritation, headache, dyspnoea, fatigue, dizziness, nausea, and intoxication were not significantly affected. No exposure-related effects on measurement of blinking frequency by electromyography, measurement of the eye break-up time, vital staining of the eye, nasal lavage biomarkers, transfer tests, spirometric and rhinometric measures were seen. No differences in response were seen between sexes or between atopics and non-atopics. Practical Implications It is important to assess acute effects in volatile organic compounds like 2-ethyl-1-hexanol. 2-ethyl-1-hexanol is often found in indoor air generated by degradation of plastic building materials or in new buildings. There are associations between 2-ethyl-1-hexanol in indoor air and respiratory effects, eye irritation, headache, and blurred vision. A controlled chamber exposure study in acute effects was performed. In conclusion, this study showed weak subjective symptom of irritation in the eyes.

Peritonectomy with high voltage electrocautery generates higher levels of ultrafine smoke particles.

BACKGROUND: To adequately perform peritonectomy, the use of an electrocautery device at a high voltage is recommended. The aim of this study was to analyse the amount of airborne and ultrafine particles (UFP) generated during peritonectomy and to compare this with standard colon and rectal cancer surgery (CRC). METHOD: UFP was measured approximately 2-3 cm from the breathing area of the surgeon (personal sampling) and 3 m from where the electrocautery smoke was generated (stationary sampling) from 14 consecutive peritonectomy procedures and 11 standard CRC resections. The sampling was by P-Trak UFP counter that has the capacity to detect particle size ranging from 0.02 to 1 microm. RESULTS: The cumulative level of UFP of personal sampling in the peritonectomy group was higher (9.3 x 10(6) particle/ml/h (pt/ml/h)) than in the control group (4.8 x 10(5) pt/ml/h). A higher cumulative level of UFP in stationary sampling was observed in the PC group (2.6 x 10(6) pt/ml/h) than in the control group (3.9 x 10(4)pt/ml/h). CONCLUSION: Peritonectomy procedure with high voltage electrocautery generates elevated levels of UFP than standard CRC surgery does. The level of UFP produced by a peritonectomy is comparable to cigarette smoking. More efficient smoke evacuator systems are needed in order to reduce the levels of UFP generated during electrocautery surgery.

Increased nitric oxide elimination from the airways after smoking cessation.

Smokers have been found to have low exhaled nitric oxide (NO) levels. The aim of the present study was to investigate where in the respiratory system the decrease in NO occurs, and whether this decrease was affected by smoking cessation. Measurements of exhaled NO were carried out in smokers (n=20) and non-smoking control subjects (n=30). In nine of the smokers, exhaled NO was analysed 1, 2 and 4 weeks after smoking cessation. The level of exhaled NO at a flow rate of 0.1 litre/s was significantly lower in smokers (4+/-2 p.p.b.) than in non-smokers (7+/-5 p.p.b.; P=0.007). A calculation of the contributions from different areas of the lung showed that the NO flux from the airways was significantly lower (14+/-10 compared with 36+/-26 nl/min; P=0.0001) and the alveolar fraction was significantly higher (2.1+/-0.8 compared with 1.5+/-0.9 p.p.b.; P=0.006) in smokers than in non-smokers. Nine smoking subjects refrained from smoking for 4 weeks, and this resulted in increased NO flux from the airways of 28+/-17 nl/min, which was no longer significantly different from controls. In conclusion, endogenous production of NO in the airways is decreased in smokers, but can be restored to normal values by 4 weeks after cessation of smoking. Smokers have an increased alveolar fraction of NO, and this might be a diagnostic sign of lung damage. Thus NO monitoring can be used to indicate improvements when a smoker decides to stop smoking.

Acoustic rhinometry and lavage biomarkers in relation to some building characteristics in Swedish schools.

It has been suggested that certain building factors can be associated with specific exposures, such as dampness, chemical emissions and dust. The aim of the study was to examine the relationships between some selected building factors, on the one hand, and signs of inflammation or obstruction in the upper airways on the other. Acoustic rhinometry and nasal lavage were used in a field study among 234 school personnel in 12 randomly selected schools (participation rate 84%). Eosinophil cationic protein (ECP), lysozyme, albumin and myeloperoxidase (MPO) were analyzed in the lavage fluid. Building related factors selected for the study were: roof inclination, fundament, building construction, signs of water damage, floor material, building age, ceiling height, bookcases and plants in the classroom. Control was made for potential confounders. The results indicate a pattern of nasal responses: less patent noses and an inflammatory biomarker response could be related to flat roof and a concrete slab fundament, factors that are known risk factors for water leakage, building dampness and possibly microbial growth. A reduced nasal patency without an inflammatory biomarker response was related to factors associated with plasticizers and dust. Positive effects were observed for plants in the classroom and in older buildings.

Nasal lavage biomarkers: effects of water damage and microbial growth in an office building.

Selected nasal symptoms were studied in personnel who worked in a damp office building that had microbial growth (including Stachybotrys sp.) in mineral fiber insulation and gypsum board. There were also signs of dampness in the floor. Clinical examinations included nasal lavage and peak expiratory flow measurements in 12 subjects in the damp building; an additional 8 subjects in a control building (i.e., no signs of dampness or microbial growth) were also examined. Hygienic air measurements of microorganisms and volatile organic compounds were performed in both buildings. The concentrations of eosinophil cationic protein, myeloperoxidase, and albumin, and the number of subjects with eosinophils in lavage fluid, were higher among office workers in the damp building than among controls. The damp biiilding had greater amounts of total molds and bacteria in its construction than the building materials in nondamp buildings. In addition, an increase of 2-ethyl-1-hexanol in the indoor air was detected in the damp building-a sign of dampness-related alkaline degradation of diethyl-hexyl phthalate in polyvinyl chloride floor coatings. In conclusion, the results of this study indicate that exposures in a damp office building may cause an inflammatory nasal mucosal response. The results also support conclusions of earlier studies, indicating that building dampness is related to respiratory inflammation.

Asthma symptoms in relation to measured building dampness in upper concrete floor construction, and 2-ethyl-1-hexanol in indoor air.

SETTING: Asthma symptoms in adults in relation to the indoor environment. OBJECTIVES: To study the relationships between current asthma symptoms (wheeze or attacks of breathlessness) and the indoor environment and dampness in hospitals. DESIGN: A study among personnel (n = 87) in four geriatric hospitals in winter. Indoor air pollutants, dampness in the concrete floor, and allergens in settled dust were measured. Multiple logistic regression analysis was applied, adjusting for age, sex, atopy, and dampness in the participants' own dwellings. RESULTS: Current asthma symptoms were reported by 17%, and 8% had doctor's diagnosed asthma. Asthma symptoms were more common (adjusted odds ratio = 8.6; 95% confidence interval 1.3-56.7) in two buildings with signs of dampness-related degradation of di(ethylhexyl)-phthalate (DEHP) in polyvinyl chloride (PVC) floor material, detected as presence of 2-ethyl-1-hexanol (2-32 microg/m3) in indoor air (CAS nr 104-76-7). Asthma symptoms were related to higher relative humidity in the upper concrete floor construction, and ammonia in the floor. The newest hospital, built by an anthroposophic society, had low levels of dampness and few asthma symptoms (4%). Cat (Fel d1) and dog allergens (Can f1) were found in dust from all buildings (geometric mean 340 ng/g and 2490 ng/g, respectively). House dust mite allergens (Derp1, Derf1, or Derm1) were found in 75% of all samples (geometric mean 130 ng/g). There was no relationship between allergen levels and asthma symptoms. CONCLUSIONS: Asthma symptoms may be related to increased humidity in concrete floor constructions and emission of 2-ethyl-1-hexanol, an indicator of dampness-related alkaline degradation of plasticiser DEHP. Moreover, geriatric hospitals can be contaminated by significant amounts of cat, dog and mite allergens.

Influence of personal factors on nasal patency and lavage biomarkers in white-collar workers.

Large biological variability between subjects has been shown for both acoustic rhinometry and nasal lavage biomarker concentrations, but relatively little is known about the influence of personal factors on these techniques. The aim was to evaluate if nasal symptoms, acoustic rhinometric measurements and nasal lavage fluid biomarkers are related to age, gender, smoking, atopy or asthma. A standardized nasal investigation was applied in 411 white-collar workers, belonging to three occupational groups: school personnel (n = 234), office workers (n = 89) and hospital workers (n = 88). Lavage fluid analysis included determination of eosinophil cationic protein (ECP), myeloperoxidase (MPO), lysozyme and albumin. Females had smaller nasal dimensions in the anterior part of the nose (p < 0.001), and lower lavage fluid concentrations of ECP (p = 0.004), MPO (p = 0.002), and albumin (p = 0.01). Rhinometric dimensions or lavage fluid biomarker concentrations were not related to age, smoking, atopy or asthma. Some differences in rhinometric and biomarker measurements were observed between the occupational groups, and adjustment was made for occupation. Rhinometric measures and lavage biomarkers were consistently interrelated, which suggests a combined mucosal swelling and inflammatory reaction. This indicates a potential usefulness of a combined use of acoustic rhinometry and lavage biomarkers to study nasal mucosal reactions.

Indoor air pollutants in schools: nasal patency and biomarkers in nasal lavage.

BACKGROUND: There is growing concern about the respiratory health aspects of the indoor air quality in schools. METHODS: A standardized investigation, including nasal lavage (NAL), measurement of the nasal cavity by acoustic rhinometry, and hygienic measurements of airborne pollutants, was performed in classrooms, outside the pollen season. All 279 school personnel working in the main buildings of 12 randomly selected primary schools in an urban community in central Sweden (Uppsala) were invited to enroll in the study; 234 (84%) participated. Eosinophil cationic protein (ECP), myeloperoxidase (MPO), lysozyme, and albumin were analyzed in NAL fluid. Crude statistical analysis, as well as multiple regression analysis, was performed, controlling for room temperature, age, sex, current smoking, and a history of atopy. RESULTS: Most classrooms (83%) did not meet the Swedish ventilation standards. A lower degree of nasal patency was found at higher concentrations of respirable dust, nitrogen dioxide (NO2), formaldehyde, and total molds, and in the presence of Aspergillus spp. in the classroom air. The most consistent findings were observed for formaldehyde, NO2, and Aspergillus spp., related to both decreased nasal patency and increase of ECP and lysozyme in NAL. The presence of yeast was associated with an increase of ECP and lysozyme in NAL, but was not related to nasal patency. CONCLUSIONS: Ventilation flow was below current hygienic standards in the classrooms. Air pollutants in the classroom air may influence nasal patency and inflammatory response in the nasal mucosa.

Acoustic rhinometry in epidemiological studies--nasal reactions in Swedish schools.

A cross-sectional study was performed on the relationships between hygienic measurements and nasal investigations in 234 personnel in 12 primary schools in mid-Sweden. Hygienic data included building characteristics, measurements of indoor air pollutants, air change rate, temperature and humidity. Clinical examinations included symptom reports, acoustic rhinometry and nasal lavage, with the determination of biomarker levels for eosinophil cationic protein (ECP), lysozyme, myeloperoxidase (MPO) and albumin. Subjective nasal obstruction was increased in schools with mechanical ventilation (adjusted prevalence OR = 2.0; 95 CI 1.1-3.7) and subjects reporting nasal obstruction had higher levels of dust in the classroom, compared to those not reporting this symptom (p = 0.008 by Mann-Whitney U-test). Congruently, a decreased nasal patency measured by acoustic rhinometric minimum cross-sectional areas (MCA1 and MCA2) was related to the use of mechanical ventilation (p = 0.008 and p = 0.02 respectively, by Mann-Whitney U-test), dust levels (p = 0.03 and p < 0.001 respectively, by Kendall's tau correlation analysis), a lower cleaning frequency of desks (p < 0.001 and p = 0.02 respectively, by Kendall's tau correlation analysis), the use of wet mopping (p < 0.001 and p = 0.04 respectively, by Mann-Whitney U-test) and PVC floor material (p < 0.001 and p = 0.034 respectively, by Mann-Whitney U-test). The cleaning frequency of floors was positively correlated with MCA1 (p = 0.049 by Kendall's tau correlation analysis). In buildings with signs of water damage, flat roof or a concrete slab fundament the personnel had increased ECP, lysozyme or albumin levels in nasal lavage. A reduced nasal patency and an increased inflammatory biomarker response were seen for higher levels of formaldehyde (MCA1, MCA2, VOL1, VOL2, ECP and lysozyme) and nitrogen dioxide (MCA1, VOL2, ECP and lysozyme) in the classrooms. In conclusion, the results indicate that acoustic rhinometry in combination with the determination of nasal lavage biomarkers can be used to study effects on the upper airways of the indoor environment. Actual exposures to indoor air pollutants in Swedish schools can affect the occurrence of subjective nasal obstruction and give clinical signs of reduced nasal patency together with an inflammatory biomarker response in the nasal mucosa.

Inflammation markers in nasal lavage, and nasal symptoms in relation to relocation to a newly painted building: a longitudinal study.

INTRODUCTION: There is a need to evaluate possible health effects of ventilation improvements and emissions from new buildings, in longitudinal studies. New methods to study biological effects on the eyes and upper airways are now available. MATERIAL AND METHODS: A longitudinal study was performed on 83 trained social workers in two offices in Uppsala, Sweden. The exposed group (n = 57) moved to a newly redecorated building nearby. Low emitting building material had been used, including a new type of solvent-free water-based paint. The control group (n = 26) worked in the same office during the study period (November 1995 to February 1996). Hygiene management was carried out in both offices, at the beginning and the end of the investigation. Tear film stability (BUT) was measured. Nasal patency was measured by acoustic rhinometry, and eosinophilic cationic protein (ECP), myeloperoxidase (MPO), lysozyme and albumin were analyzed in nasal lavage fluid (NAL). RESULTS: The relocation resulted in an increase in the personal outdoor airflow rate from 11 to 22 l/s. Indoor concentrations of terpenes were higher in the new building, and powdering of the new linoleum floor was observed. Measurements showed low levels of volatile organic compounds (VOC), formaldehyde, carbon dioxide (CO(2)), nitrogen dioxide, respirable dust, and microorganisms in the air of all buildings. The move resulted in an increased nasal patency and an increase of ECP and lysozyme in NAL, after adjusting for changes in the control group. No changes were observed for nasal or ocular symptoms. A seasonal effect, with a decrease of ECP, was observed in the control group. CONCLUSSION A well-ventilated office building can be redecorated without any major ocular or nasal effects, or measurable increase of indoor air pollution if low-emitting building materials are selected. In agreement with previous evidence, the improved ventilation flow may explain the increase of nasal patency. The increase of ECP and lysozyme in NAL suggested an inflammatory effect in the new building. Since this building had increased ventilation flow, increased concentrations of terpenes, and powdering from the polish on the new linoleum floor, identification of causative agents was difficult. The hygiene measures did not give any evidence that emissions from the new type of solvent-free water-based paints or building dampness were responsible for the observed nasal effects. Considering the higher emissions of VOC reported from older types of water-based latex paints and solvent-based wall paints, the new type of solvent-free water-based paint seems to be a good choice from the hygiene point of view.

Nasal and ocular symptoms, tear film stability and biomarkers in nasal lavage, in relation to building-dampness and building design in hospitals.

OBJECTIVES: To study the relationships between dampness in concrete floors and building design on the one hand, and symptoms and medical signs of the eyes and nose in hospital workers, on the other. METHODS: Four hospitals for geriatrics were selected to represent buildings with different ages and design, irrespective of symptom prevalence. The first building was built in 1925. The second, built in 1985, was known to have dampness in the floor. Conventional building techniques were used in the third building, built in 1993, and the last building was built in 1994, and was specially designed to include high ceilings, and minimal use of fluorescent lighting and interior plastic materials. The interior surfaces were painted with water-based beeswax glazing. All staff (n=95) working day shifts were invited to take part in a medical examination of the eyes and nose including acoustic rhinometry and nasal lavage, and a medical questionnaire, and 93% participated. Measurements of temperature, relative air humidity, air flow, illumination, volatile organic compounds (VOCs), molds, and bacteria were carried out in all buildings, together with measurements of formaldehyde, respirable dust, carbon monoxide (CO), carbon dioxide (CO(2)), nitrogen dioxide (NO(2)) and ozone. Statistical analyses were performed by bivariate analysis, and linear, ordinal, and logistic multiple regressions, adjusting for age, gender, tobacco smoking, atopy, and the perceived psychosocial work environment. RESULTS: Dampness in the upper concrete floor surface (75-84%), ammonia under the floor [3 parts per million (ppm)], and 2-ethyl-1-hexanol in the air were detected in the two buildings built in 1985 and 1993. Increased occurrences of ocular and nasal symptoms, an increased concentration of lysozyme in nasal lavage, and decreased tear film stability were found in the subjects working in the damp buildings. Those in the specially designed building had fewer ocular and nasal symptoms, and increased tear film stability. All buildings had low levels of formaldehyde, molds, bacteria, ozone, and NO(2). The lowest total concentration of VOCs, and the highest concentration of specific VOCs of microbial origin, were found in the building with special design. CONCLUSION: The study provides new evidence of the role of dampness-related alkaline degradation of di-(2-ethylhexyl) phthalate (DEHP) in polyvinyl chloride (PVC) building material. Emissions related to degradation of DEHP due to dampness in the floor, indicated by increased 2-ethyl-1-hexanol in the air, seem to increase both the secretion of lysozyme from the nasal mucosa and the occurrence of ocular and nasal symptoms. The indoor environment of the specially designed building with high ceilings and no fluorescent lighting or interior plastics seemed to have a positive influence on the nasal and ocular mucous membranes.

Nasal patency and lavage biomarkers in relation to settled dust and cleaning routines in schools.

OBJECTIVES: This study determined the relations between settled dust and cleaning routines in classrooms on one hand, and nasal symptoms, nasal cavity dimensions, and the concentration of selected biomarkers of inflammation in nasal lavage on the other. METHODS: Measurements of settled dust via standardized vacuum cleaning and an investigation of the cleaning routines were performed in 12 randomly selected primary schools in the municipality of Uppsala. Clinical examinations including acoustic rhinometry and nasal lavage were performed in the school environment among 279 school personnel working in the main buildings of the schools. Eosinophil cationic protein (ECP), myeloperoxidase (MPO), lysozyme, and albumin were analyzed in the lavage fluid. The relationships between the medical and hygienic data were analyzed both bivariately and with a multiple regression model controlling for age, gender, smoking, atopy, room temperature, and urban vicinity of the school. RESULTS: The amount of settled dust was positively related to subjective nasal obstruction and smaller nasal cavity dimensions measured with acoustic rhinometry. The noses were less patent, and the levels of ECP or lysozyme in the lavage were increased for the subjects in schools with a lower frequency of floor mopping, a lower frequency of desk cleaning, and where wet mopping was used. CONCLUSIONS: Our results indicate that the actual dust levels in Swedish classrooms can affect the occurrence of nasal obstruction among school personnel. A beneficial effect on the clinical signs of the nasal mucosa was observed for a higher frequency of both floor mopping and desk cleaning, whereas the use of wet mopping seemed disadvantageous in comparison with dry mopping. These findings illustrate the need for adequate cleaning procedures to minimize the environmental effects on the airway mucosa.

Pulmonary reactions after exposure to 3-methylfuran vapour, a fungal metabolite.

A case of obstructive pulmonary reaction with flu-like symptoms after exposure to 3-methylfuran is described. This compound is produced by fungi, and can be found in buildings with mould growth. Previous studies have shown that exposure to the substance might increase the prevalence of respiratory symptoms, and is pneumotoxic to animals at high concentrations.

Nasal patency and biomarkers in nasal lavage--the significance of air exchange rate and type of ventilation in schools.

OBJECTIVES: The aim of the present study was to examine the relationships between the ventilation rate and the type of ventilation system, on the one hand, and objective nasal measures, on the other. METHODS: A standardized investigation, including acoustic rhinometry and nasal lavage, was performed in the school environment. All 279 school personnel working in the main buildings of 12 randomly selected primary schools in the municipality of Uppsala were invited, and 234 (84%) participated. The dimensions of the nasal cavity were measured with acoustic rhinometry. Eosinophil cationic protein (ECP), myeloperoxidase (MPO), lysozyme, and albumin were analyzed in the lavage fluid. The air exchange rate and the room temperature were measured in the classrooms. Relationships between nasal symptoms, nasal patency, and the concentration of biomarkers, on the one hand, and the type of ventilation system, the air exchange rate, and the temperature, on the other, were analyzed by both crude bivariate analysis and multiple regression models, controlling for the type of ventilation, the air exchange rate, room temperature, age, gender, smoking, atopy, and the urban vicinity of the school. RESULTS: A lower degree of nasal patency as measured by acoustic rhinometry and increased levels of ECP and lysozyme in nasal lavage were associated with a lower air exchange rate in the schools. Although mechanically ventilated schools had higher air exchange rates, they were associated with more nasal symptoms, and nasal mucosal swelling and with increased lavage levels of ECP and lysozyme as compared with schools with natural ventilation only. In contrast, 12 subjects working in a school with mechanical displacement ventilation had more patent noses and lower levels of inflammatory markers as compared with the personnel in schools with natural ventilation only. CONCLUSION: Our results indicate that both a low air exchange rate and mechanical ventilation systems based on dilution can be associated with reduced nasal patency and an inflammatory biomarker response of the nasal mucosa among school personnel. The only school with sufficient ventilation according to the current Swedish recommendations had a displacement system and the fewest signs of nasal reactions among the personnel.

Experimental exposure to methyl tertiary-butyl ether. II. Acute effects in humans.

Methyl tertiary-butyl ether (MTBE) is widely used in gasoline as an oxygenate and octane enhancer. Acute effects, such as headache, nausea, and nasal and ocular irritation, have been associated with the exposure to gasoline containing MTBE. The aim of this study was to assess acute health effects up to the Swedish occupational exposure limit value, both with objective methods and a questionnaire. Ten healthy male volunteers were exposed to MTBE vapor for 2 h at three levels (5, 25, and 50 ppm), during light physical work (50 W). All subjects rated the degree of irritative symptoms, discomfort, and CNS effects before, during, and after all three exposure occasions using a questionnaire. Answers were given on a 100-mm visual analog scale, graded from "not at all" to "almost unbearable." Ocular (redness, tear film break-up time, self-reported tear film break-up time, conjunctival epithelial damage, and blinking frequency) and nasal (mouth and nasal peak expiratory flow, acoustic rhinometry, biochemical inflammatory markers, and cells in nasal lavage) measurements were performed mainly at the highest exposure level. The ratings of solvent smell increased dramatically (ratings up to 50% of the scale) as the volunteers entered the chamber and declined slowly with time (p < 0.05, repeated-measures ANOVA). All other questions were rated from "not at all" to "hardly at all" (0-10% of the scale) with no significant relation to exposure. The eye measurements showed no effects of MTBE exposure. Blockage index, a measure of nasal airway resistance calculated from the peak expiratory flows, increased significantly after exposure; however, the effect was not related to exposure level. In addition, a nonsignificant tendency of decreased nasal volume was seen in the acoustic rhinometry measurements, but with no clear dose-effect relationship. In conclusion, our study suggests no or minimal acute effects of MTBE vapor upon short-term exposure at relatively high levels.

Nasal congestion in relation to low air exchange rate in schools. Evaluation by acoustic rhinometry.

Upper airway symptoms are common, but there is little information available on clinical findings in relation to indoor air pollution. This pilot study was conducted to test whether increased levels of indoor air pollutants in schools may correlate to a swelling of the nasal mucosa. The assumption was made that the degree of swelling could be related to the degree of decongestive effect of xylometazoline, and measured by acoustic rhinometry. The study was performed among 15 subjects in a school with low air exchange rate (0.6 air changes/h) and 12 subjects in a school with high air exchange rate (5.2 air changes/h). Hygienic measurements were performed in both schools. Acoustic rhinometry was performed for each individual under standardized forms. Cross-sectional areas and volumes of the nasal cavity were measured before and after decongestion with xylometazoline hydrochloride. Absolute values of the minimal cross-sectional area were lower in the school with poor ventilation. The decongestive effect of xylometazoline was significantly higher in the school with low air exchange, when correction for the influence of age was made. A diminished decongestive effect was seen with increasing age. The exposure measurements showed that indoor concentrations of volatile organic compounds, bacteria and moulds were higher in the school with low ventilation. In conclusion, raised levels of indoor air pollutants due to inadequate ventilation in schools may affect the upper airways and cause a swelling of the nasal mucosa, and acoustic rhinometry could be a useful objective method to measure human nasal reactions to the indoor environment.