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 CO2 (ETCO2) and Fractional concentration of Inspired CO2 (FICO2) at rest and on mild exertion, as expected. The use of the mask with MF brought FICO2 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.