Street temperature and building characteristics as determinants of indoor heat exposure.

Higher temperatures are associated with morbidity and mortality. Most epidemiological studies use outdoor temperature data, however, people spend most of their time indoors. Indoor temperatures and determinants of indoor temperatures have rarely been studied on a large scale. We measured living room and bedroom temperature in 113 homes of elderly subjects, as well as outdoor temperatures, in two cities in the Netherlands. Linear regression was used to determine the influence of building characteristics on indoor living room and bedroom temperatures in the warm episode. During the warm episode, indoor temperatures were higher during the night and lower during the day than outdoor temperatures. Indoor temperatures on average exceeded outdoor temperatures. The weekly average indoor temperature in living rooms varied between 23.1 and 30.2 °C. Dwellings that warmed up easily, also cooled down more easily. Outdoor and indoor temperatures were moderately correlated (R2 = 0.36 and 0.34 for living rooms and bedrooms, respectively). Building year before 1930 and rooms being located on the top floor were associated with higher indoor temperatures. Green in the vicinity was associated with lower temperatures in bedrooms. This study shows that indoor temperatures vary widely between dwellings, and are determined by outdoor temperatures and building characteristics. As most people, especially the elderly, spend most of the time indoor, indoor temperature is a more exact predictor of heat exposure than outdoor temperature. The importance of mitigating high indoor temperatures will be more important in the future because of higher temperatures due to climate change.

Air pollution during New Year's fireworks and daily mortality in the Netherlands.

Short-term exposure to air pollution has been associated with cardiovascular and respiratory mortality and morbidity. Little is known about associations between air pollution caused by firework events and daily mortality. We investigated whether particulate matter from fireworks during New Year's celebrations was associated with daily mortality. We analyzed the celebrations of the years 1995-2012. PM10 concentrations increased dramatically during the firework events. Countrywide, the daily average PM10 concentrations from 27-30 December was 29 µg/m3 and increased during the first hour of the New Year by 277 µg/m3. In the more densely populated areas of the Netherlands the increase was even steeper, 598 µg/m3 in the first hour of the New Year. No consistent associations were found using linear regression models between PM10 concentrations during the first six hours of 1 January and daily mortality in the general population. Yet, using a case-crossover analysis firework-days and PM10 concentrations were associated with daily mortality. Therefore, in light of the contradictory results obtained with the different statistical analyses, we recommend further epidemiological research on the health effects of exposure to firework emissions.

Where there's smoke, there's fire: focal points for risk communication.

Large fires involving hazardous materials are often characterized by failing crisis communication. In this study, we compared opinions of experts regarding the risks of major fires to lay beliefs using a mental models approach. Amongst lay people this revealed relevant knowledge gaps and beliefs in opposition to those held by experts. While, experts considered the chance of getting cancer from inhaling smoke from a chemical fire extremely small, most lay people thought that even at a great distance, the chance of getting cancer to be large. To improve crisis communication about risk in a case of large chemical fires, and reduce the potential for messages to be misunderstood, distrusted or dismissed, we recommend a clarification of cancer risk in communications about public health emergencies such as chemical fires, for which lay people equate even small exposures to carcinogenic chemicals make one more likely to get cancer later in life.

A ventilation intervention study in classrooms to improve indoor air quality: the FRESH study.

BACKGROUND: Classroom ventilation rates often do not meet building standards, although it is considered to be important to improve indoor air quality. Poor indoor air quality is thought to influence both children's health and performance. Poor ventilation in The Netherlands most often occurs in the heating season. To improve classroom ventilation a tailor made mechanical ventilation device was developed to improve outdoor air supply. This paper studies the effect of this intervention. METHODS: The FRESH study (Forced-ventilation Related Environmental School Health) was designed to investigate the effect of a CO2 controlled mechanical ventilation intervention on classroom CO2 levels using a longitudinal cross-over design. Target CO2 concentrations were 800 and 1200 parts per million (ppm), respectively. The study included 18 classrooms from 17 schools from the north-eastern part of The Netherlands, 12 experimental classrooms and 6 control classrooms. Data on indoor levels of CO2, temperature and relative humidity were collected during three consecutive weeks per school during the heating seasons of 2010-2012. Associations between the intervention and weekly average indoor CO2 levels, classroom temperature and relative humidity were assessed by means of mixed models with random school-effects. RESULTS: At baseline, mean CO2 concentration for all schools was 1335 ppm (range: 763-2000 ppm). The intervention was able to significantly decrease CO2 levels in the intervention classrooms (F (2,10) = 17.59, p < 0.001), with a mean decrease of 491 ppm. With the target set at 800 ppm, mean CO2 was 841 ppm (range: 743-925 ppm); with the target set at 1200 ppm, mean CO2 was 975 ppm (range: 887-1077 ppm). CONCLUSIONS: Although the device was not capable of precisely achieving the two predefined levels of CO2, our study showed that classroom CO2 levels can be reduced by intervening on classroom ventilation using a CO2 controlled mechanical ventilation system.

Respiratory effects in the aftermath of a major fire in a chemical waste depot.

OBJECTIVES: The aim of this study was to investigate respiratory effects among emergency services first responders and residents with exposure to combustion products in the aftermath of a chemical waste depot fire. METHODS: The study population comprised 138 individuals who were present in the area downwind of an accidental fire. Identified by telephone interview six years later, subjects with persistent respiratory symptoms were suspected as having Reactive Airways Dysfunction Syndrome (RADS). Medical tests were performed. For bronchial responsiveness, a cut-off point of PD (20)<2.39 mg histamine was taken and a dose-response slope (DRS) was calculated. Suspected RADS cases were compared with healthy controls for exposure to combustion products, lung function, and bronchial responsiveness. RESULTS: The 25 suspected RADS cases were more frequently exposed than the 99 controls; the crude odds ratio for high versus low exposure was 6.5 [95% confidence interval (95% CI) 2.4-18.0]. Suspected cases showed a lower ratio of forced expiratory volume in one second to forced vital capacity (FEV(1)/FVC; P=0.028). Overall, suspected cases had higher DRS than controls. The difference was significant for males only (P=0.006), and non-smoking males (P=0.014). Highly exposed subjects had higher DRS than low exposed subjects (P=0.056). These differences were significant when restricted to non-smokers (P=0.034) and to males (P=0.019). Differences between cases and controls were stronger when the population was restricted to current non-smokers. CONCLUSIONS: Persistent respiratory symptoms and bronchial responsiveness were associated with exposure to combustion products of a chemical waste depot fire which occurred more than six years earlier. Authorities and emergency services are recommended to take this into consideration when managing incidents in order to limit possible exposure to airway irritants.