AIVC - Air Infiltration and Ventilation Centre

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occupant reaction

Background sound pressure fluctuations (5 dB) from overhead ventilation systems increase subjective fatigue of university students during three-hour lectures.

An experiment was performed in a lecture hall on students, to assess the effect of ventilation noise on concentration and fatigue. The students were tested with the ventilation fans both on and off. As a group the students reported more fatigue during lectures when the fans were operating. States that this environmental effect explains about 39% of the variance in fatigue ratings and may be sufficient to affect adversely the attention of students within these settings.

Ventilation requirements for the control of body odour in spaces occupied by women.

The intensity and acceptability of body odour was assessed 29 times on entering an experimental auditorium occupied by 106 women, by 40 female and 39 male judges. The experiment lasted 3 hours 50 minutes and the ventilation rate was varied while the air temperature was maintained at around 20-21 deg C. CO2 was measured throughout. It was found that there were no substantial differences in the ventilation rates required in rooms occupied by men and women. In order to satisfy 80% of people entering a space, a steady-state ventilation rate of about 8 L/sec person is necessary.

Ventilation requirements for cigarette smoke.

The study evaluated the strength of tobacco smoke odour by sense of smell. Similar tests were done for other irritants in tobacco smoke. Concludes that an outside air supply of 35 to 40 cfm per smoker is required to remove objectionable odours of fresh cigarette smoke. Also concludes that there in no way to ascertain whether the ventilation requirements for controlling smoke, odour and irritation effects are adequate to protect a non-smoker from possible effects of nicotine and other poisonous elements of smoke of unknown toxicological thresholds.

Estimating human exposure to nitrogen dioxide: an indoor/outdoor modelling approach.

Human exposure to nitrogen dioxide can have adverse health effects. Policymakers need accurate information on the number of people exposed, the severity and patterns of exposure and the health-related effects of the exposure, in order to assess health risks and bring in appropriate control strategies. Data from central monitoring sites have been used in the past to establish air pollution exposures. Attempts to provide a realistic estimate of nitrogen dioxide exposures.

Carbon dioxide, particulates and subjective human responses in office buildings without histories of indoor air quality problems.

States that carbon dioxide measurements are commonly used to indicate fresh air in a building, also particulate levels. The study's aim was to evaluate the relationship between carbon dioxide and particulate levels and subjective human responses in office building without previous or present indoor air problems. Six separate ventilation zones were defined and carbon dioxide and particulate measurements taken with direct-reading instruments. A self-reporting questionnaire, designed in Sweden was used for the subjective human responses.

Volatile organic compounds, respirable dust, and personal factors related to prevalence and incidence of sick building syndrome in primary schools.

This study explored the possible connections between the incidence and prevalence of sick building syndrome (SBS), indoor exposures, and personal factors. This was accomplished by a four year longitudinal study of workers in six primary schools. The mean concentration of Carbon Dioxide exceeded the recommended value of 0.08 microlitres/l (800 ppm) in all schools, which suggested a poor outdoor air supply. Indoor levels of volatile hydrocarbon (VOC) was increased at high room temperatures.

A typically frustrating building investigation.

Describes a case study of the NIOSH investigation of the 101 Marietta Tower in Atlanta, USA, a high rise office building suffering from sick building syndrome. Concludes that the use of conventional industrial hygiene approaches for conducting indoor air quality investigations will in most cases by non-productive. States that first efforts should be directed toward understanding and evaluating the operation of the building's HVAC system to determine that enough outdoor air is provided. Distributing a follow-up questionnaire to the occupants is also important.

Indoor climate and air quality in new offices: effects of a reduced air-exchange rate.

Describes an evaluation made of employee health complaints at a credit bank. A self-administered questionnaire determined the symptoms. The authors looked at ventilation effectiveness, contaminant concentrations and microclimate in relation to employee discomfort and health problems. Relatively high levels of carbon dioxide and bioaerosols were found, although temperature and humidity were normal. The authors suggest that an ineffective rate of room air exchange may be a significant factor.

Personalised ventilation: evaluation of different air terminal devices.

The effectiveness of personalized ventilation based on air movement around a room's occupant largely depends on the supply air terminal device or ATD. Five different ATDs were tried and compared. A normal office workplace with a desk and mounted ATDs was simulated in a climate chamber. An office worker was simulated by a breathing thermal manikin. Tests were performed at various air temperatures of 26C and 20C and personalized air temperatures of 20, 23 and 26C provided by the ATD. The flow of personalized air was increased from less than 5 L/s up to 23 L/s.

Perceived air quality and performance of subjects in room with different air pollution levels.

In an office renovate one year previously, a study of perceived air quality, sick building syndrome symptoms and subject performance was made. Thirty one female college age subjects were exposed to the conditions in the same office with an outdoor airflow of 280 m3/h and 45 m3/h. The subjects assessed perceived air quality and SBS symptoms while performing simulated work. Formaldehyde and VOC measurements were much higher in the room with lower ventilation rate, though no significant difference was noted in odour intensity.