EBC will be collected using the ECoscreen (Jaeger, Germany) according to manufacturer instructions. After rinsing their mouth, the recruited subjects will breathe tidally through a mouthpiece that is connected through a unique one-way valve into a cooled collection tube where vapours, aerosols and moisture in the breath condense along the walls of the tube. The one-way valve is then used as a plunger that collects droplets stuck to the inside wall and holds the sample near the top of the tube. The device inherently prevents salivary contamination as shown by the absence of salivary amylase in EBC. On average, this device will be able to collect 300 microL per minute of EBC for an adult. Each subject will be asked to breathe through the collection kit for 5 minutes, which should be sufficiently long to yield 1 ml of condensate for inflammatory marker analysis. EBC will be stored immediately at -70oC until analysis for inflammatory markers.