UNLABELLED:The concentration of nitric oxide (NO) in exhaled and aspirated nasal air was used to objectively assess human response to indoor air pollutants in a climate chamber exposure experiment. The concentration of NO was measured before exposure, after 2, and 4.5 h of exposure, using a chemiluminescence NO analyzer. Sixteen healthy female subjects were exposed to two indoor air pollutants and to a clean reference condition for 4.5 h. Subjective assessments of the environment were obtained by questionnaires. After exposure (4.5 h) to the two polluted conditions a small increase in NO concentration in exhaled air was observed. After exposure to the reference condition the mean NO concentration was significantly reduced compared to pre-exposure. Together these changes resulted in significant differences in exhaled NO between exposure to reference and polluted conditions. NO in nasal air was not affected by the exposures. The results may indicate an association between polluted indoor air and subclinical inflammation.PRACTICAL IMPLICATIONS:Measurement of nitric oxide in exhaled air is a possible objective marker of subclinical inflammation in healthy adults.

UNLABELLED:A 21-seat section of an aircraft cabin with realistic pollution sources was built inside a climate chamber capable of providing fresh outside air at very low humidity. Maintaining a constant 200 l/s rate of total air supply, i.e. recirculated and make-up air, to the cabin, experiments simulating 7-h transatlantic flights were carried out at four rates of fresh outside air supply--1.4, 3.3, 4.7, and 9.4 l/s per person (3, 7, 10, and 20 cfm/person)--resulting in humidity levels, ranging from 7% to 28% relative humidity (RH). Four groups of 16-18 subjects acted as passengers and crew and were each exposed to the four simulated flight conditions. During each flight the subjects completed questionnaires three times to provide subjective ratings of air quality and of symptoms commonly experienced during flight. Physiological tests of eye, nose, and skin function were administered twice. Analysis of the subjective assessments showed that increasing RH in the aircraft cabin to 28% RH by reducing outside flow to 1.4 l/s per person did not reduce the intensity of the symptoms that are typical of the aircraft cabin environment. On the contrary, it intensified complaints of headache, dizziness, and claustrophobia, due to the increased level of contaminants.PRACTICAL IMPLICATIONS:The investigation shows that increasing aircraft cabin humidity by decreasing the ventilation flow rate of fresh outside air would not decrease reports of discomfort made by cabin occupants.

Thirty subjects (17 female) were exposed for five hours in a climate chamber at 22°C (71.6°F) to clean air at 5%, 15%, 25%, and 35% RH. A comparable group was similarly exposed to air polluted by carpet and linoleum to the 35% RH condition and to 18°C, 22°C, and 26°C (64.4°F, 71.6°F, and 78.8°F) at an absolute humidity equal to 15% RH at 22°C (71.6°F). They performed simulated office work to ensure that they kept their eyes open and reported sick building syndrome (SBS) symptom intensity on visual-analogue scales. Nine objective tests of eye, nose, and skin function were applied. Subjective discomfort, though significantly increased by low humidity, was slight even at 5% RH. More rapid blink rates were observed at 5% than at 35% RH (P < 0.05), and tear film quality as indicated by the Mucous Ferning Test deteriorated (P < 0.05) at low humidity (5%, 15%) and at the highest air temperature 18°C, 22°C > 26°C (78.8°F). Low humidity was found to have reduced the rate of performance of three office tasks by 3%–7%.

Low humidity in the aircraft cabin environment has been identified as a possible cause of symptoms experienced during long flights. A mock-up of a 21-seat section of an aircraft cabin with realistic pollution sources was built inside a climate chamber, capable of providing fresh outside air at very low humidity. Experiments simulating 7-hour transatlantic flights were carried out at four outside air supply rates - 1.4, 3.3, 4.7 and 9.4 L/s per person (3, 7, 10 and 20 cfm/p) - yielding average humidity levels of 28%, 16%, 11% and 7% RH respectively. Four groups of 16-18 subjects were exposed to the four conditions. The subjects completed questionnaires to provide subjective assessments of symptoms commonly experienced during flights. Increasing humidity to 28% RH by reducing outside air supply rate did not reduce the intensity of the symptoms typical of the aircraft cabin environment, and intensified headache, dizziness and claustrophobia.

The present paper shows that introducing or removing the same pollution source in an office in two independent investigations, one in Denmark and one in Sweden, using similar experimental methodology, resulted in similar and repeatable effects on subjective assessments of perceived air quality, intensity of sick building syndrome symptoms and performance of office work. Removing the pollution source improved the perceived air quality, decreased the perceived dryness of air and the severity of headaches, and increased typing performance. These effects were observed separately in each experiment and were all significant (P < or = 0.05) after combining the data from both studies, indicating the advantages of pollution source strength control for health, comfort, and productivity.