Children are more vulnerable to the risks of air pollution, including susceptibility to acquiring chronic diseases in their developing lungs. Despite these, there are no specific masks designed for and tested in children that are available to protect our young from the common particulate air pollutants today. We evaluated safety, fit and comfort of a specially designed paediatric N95 mask with an optional micro ventilator (micro fan, MF) in healthy children aged 7-14 years, in a randomized, two-period crossover design. The subjects' cardiorespiratory physiological measurements were assessed in different states of physical activity under different interventions (mask without and with MF). A total of 106 subjects were recruited between July-August 2016. The use of the mask without MF increased the End-Tidal CO 2 (etco 2 ) and fractional concentration of inspired co 2 (fico 2 ) at rest and on mild exertion, as expected. The use of the mask with MF brought FICO 2 levels comparably closer to baseline levels without the mask for both activities. The mask, with or without the MF, was found to be well fitting, comfortable and safe for use in children at rest and on mild exertion. The N95 mask tested offers a promising start for more studies in the paediatric population. Air pollution, such as haze or smog, is an evolving and increasingly significant problem around the world. A wide range of hazards of chronic air pollution in children include nocturnal cough, asthma, poor performance in neurobehavioral function, negative impact in cognitive development and harmful effects on brain development 1-5 . In particular, children represent a vulnerable segment of any population. They carry more risks of long term exposure to pollution over the course of their lives and are susceptible to acquiring chronic diseases in their developing lungs 6-11 . Use of masks and respirators can offer protection against air pollutants. However, the commercially available disposable particulate respirators, typically certified for surgical (which may only offer some barrier against larger particles) and occupational use, are mainly designed for and studied in adults. The test standards are specified according to adult breathing conditions and fit. There are to date, no masks designed for and evaluated in children. Several studies have investigated the effectiveness, safety, fit and comfort of different types of masks 12-15 . However these studies were done only in adult populations. Even alternatives such as cloth masks have been tested only in adult populations 16 . In another study, the facemasks for paediatric use (FPU, the masks that are not specifically designed for paediatric use but are the existing mask that may be used for children during emergency situation like that of airborne disease outbreaks) were tested mainly to evaluate the leakage associated with donning the FPU 17 . This study did show superiority of FPU in comparison to surgical masks in certain aspects, however, the study was not performed in children. One study was performed in children to evaluate the redesigned open system face mask. However, the objective of this study was to evaluate the mask for monitoring P ETCO2 during sedation in clinical practice and the children in this study donned the mask only for 30 sec. 18 . These and other similar studies merely point to the fact that there are no masks that are specifically designed and tested in children such that they can be prescribed for paediatric use in the setting of daily routine activities. In our study, the N95 masks were specifically designed for use in children and they were evaluated in children under conditions of routine daily activities. They are the first to be paired with a micro ventilator (micro fan, MF), designed to reduce the accumulation of exhaled carbon dioxide (CO 2 ), heat and humidity in the dead space of
Output: A randomised clinical trial to evaluate the safety, fit, comfort of a novel N95 mask in children