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BackgroundClassroom 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.MethodsThe 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.ResultsAt 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).ConclusionsAlthough 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.

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. PM 10 concentrations increased dramatically during the firework events. Countrywide, the daily average PM 10 concentrations from 27–30 December was 29 μg/m 3 and increased during the first hour of the New Year by 277 μg/m 3 . In the more densely populated areas of the Netherlands the increase was even steeper, 598 μg/m 3 in the first hour of the New Year. No consistent associations were found using linear regression models between PM 10 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 PM 10 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.

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.

Objective The aim of this study was to investigate respiratory effects among emergency services first responders and residents exposed 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. ResultsThe 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 a 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 a higher DRS than low exposed subjects (P=0.056). These differences were significant when restricted to non-smokers (P=0.034) and 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.