Urban daily life routines and human exposure to environmental discomfort

With considerably increased coverage of weather information in the news media in recent years in many countries, there is also more demand for data that are applicable and useful for everyday life. Both the perception of the thermal component of weather as well as the appropriate clothing for thermal comfort result from the integral effects of all meteorological parameters relevant for heat exchange between the body and its environment. Regulatory physiological processes can affect the relative importance of meteorological parameters, e.g. wind velocity becomes more important when the body is sweating. In order to take into account all these factors, it is necessary to use a heat-balance model of the human body. The physiological equivalent temperature (PET) is based on the Munich Energy-balance Model for Individuals (MEMI), which models the thermal conditions of the human body in a physiologically relevant way. PET is defined as the air temperature at which, in a typical indoor setting (without wind and solar radiation), the heat budget of the human body is balanced with the same core and skin temperature as under the complex outdoor conditions to be assessed. This way PET enables a layperson to compare the integral effects of complex thermal conditions outside with his or her own experience indoors. On hot summer days, for example, with direct solar irradiation the PET value may be more than 20 K higher than the air temperature, on a windy day in winter up to 15 K lower.

This paper reviews current literature on the associations of ventilation rates and carbon dioxide concentrations in non-residential and non-industrial buildings (primarily offices) with health and other human outcomes. Twenty studies, with close to 30,000 subjects, investigated the association of ventilation rates with human responses, and 21 studies, with over 30,000 subjects, investigated the association of carbon dioxide concentration with these responses. Almost all studies found that ventilation rates below 10 Ls-1 per person in all building types were associated with statistically significant worsening in one or more health or perceived air quality outcomes. Some studies determined that increases in ventilation rates above 10 Ls-1 per person, up to approximately 20 Ls-1 per person, were associated with further significant decreases in the prevalence of sick building syndrome (SBS) symptoms or with further significant improvements in perceived air quality. The carbon dioxide studies support these findings. About half of the carbon dioxide studies suggest that the risk of sick building syndrome symptoms continued to decrease significantly with decreasing carbon dioxide concentrations below 800 ppm. The ventilation studies reported relative risks of 1.5-2 for respiratory illnesses and 1.1-6 for sick building syndrome symptoms for low compared to high low ventilation rates.

The burnout syndrome denotes a constellation of physical fatigue, emotional exhaustion, and cognitive weariness resulting from chronic stress. Although it overlaps considerably with chronic fatigue as defined in internal medicine, its links with physical illness have not been systematically investigated. This exploratory study, conducted among 104 male workers free from cardiovascular disease (CVD), tested the association between burnout and two of its common concomitants--tension and listlessness--and cardiovascular risk factors. After ruling out five possible confounders (age, relative weight, smoking, alcohol use, and sports activity), the authors found that scores on burnout plus tension (tense-burnout) were associated with somatic complaints, cholesterol, glucose, triglycerides, uric acid, and, marginally, with ECG abnormalities. Workers scoring high on tense-burnout also had a significantly higher low density lipoprotein (LDL) level. Conversely, scores on burnout plus listlessness were significantly associated with glucose and negatively with diastolic blood pressure. The findings warrant further study of burnout as a predictor of cardiovascular morbidity and mortality.