Air Under the Net: Heat and Carbon Dioxide Beneath a Mosquito Net Draped over a Cot

A mosquito net over a cot protects a sleeping infant from biting insects, but it also encloses the air the infant breathes and warms. This paper computes, from stated assumptions, the steady-state carbon dioxide level and temperature rise inside a netted cot, and derives a design rule for how the net must be supported. The cot measures 1.20 m by 0.60 m; the reference infant of 5 kg produces 25.5 mL per minute of carbon dioxide and 9.5 W of heat. The binding constraint is heat, not carbon dioxide: holding the temperature rise to 1.5 °C requires an air flow of 5.28 L/s, while holding total carbon dioxide to 1200 ppm requires only 0.54 L/s. In still air, a single-layer net supported 0.6 m above the mattress passes 10.37 L/s, giving a carbon dioxide level of 461 ppm and a temperature rise of 0.76 °C. The design rule that follows is a minimum support height of 0.45 m for an infant up to 5 kg and 0.6 m for an infant up to 10 kg, with a single layer of standard mesh and no second layer added. The failures are as important as the passes: a double-layer net at 0.3 m support height gives a temperature rise of 2.04 °C and fails; a 10 kg infant under a double layer fails the heat limit at every modelled height up to 1.0 m, with a rise of 1.52 °C; and in a sealed 12 m³ room the room air itself reaches 1440 ppm of carbon dioxide after 8 hours, so the air inside the net reaches 1481 ppm and no passive net arrangement passes, because the net can only exchange the infant's air with the room's.