<P> Low humidity may occur in hot, dry desert climates, or indoors in artificially heated spaces . In winter, especially when cold outside air is heated indoors, the humidity may drop to as low as 10--20% . This low humidity can cause adverse health effects, by drying out mucous membranes such as the lining of the nose and throat, and can cause respiratory distress . The low humidity also can affect wooden furniture, causing shrinkage and loose joints or cracking of pieces . Books, papers, and artworks may shrink or warp and become brittle in very low humidity . </P> <P> In addition, static electricity may become a problem in conditions of low humidity, destroying semiconductor devices, causing static cling of textiles, and causing dust and small particles to stick stubbornly to electrically charged surfaces . </P> <P> Overuse of a humidifier can raise the relative humidity to excessive levels, promoting the growth of dust mites and mold, and can also cause hypersensitivity pneumonitis (humidifier lung). A relative humidity of 30% to 50% is recommended for most homes . A properly installed and located hygrostat should be used to monitor and control humidity levels automatically, or a well - informed and conscientious human operator must constantly check for correct humidity levels . </P> <P> Industrial humidifiers are used when a specific humidity level must be maintained to prevent static electricity buildup, preserve material properties, and ensure a comfortable and healthy environment for workers or residents . </P>

Describe the difference between an evaporative and an atomizing humidifier