Room temperature
Colloquially, "room temperature" is a range of air temperatures that most people prefer for indoor settings. It feels comfortable to a person when they are wearing typical indoor clothing. Human comfort can extend beyond this range depending on humidity, air circulation and other factors. In certain fields, like science and engineering, and within a particular context, "room temperature" can mean different agreed-upon ranges. In contrast, "ambient temperature" is the actual temperature, as measured by a thermometer, of the air (or other medium and surroundings) in any particular place. The ambient temperature (e.g. an unheated room in winter ) may be very different from an ideal "room temperature". Comfort temperatures. "The American Heritage Dictionary of the English Language" identifies room temperature as around , while the "Oxford English Dictionary" states that it is "conventionally taken as about ". The ideal room temperature may vary by place and culture; studies from Nigeria show a comfortable temperature range of , comfortably cool and comfortably warm . Owing to variations in humidity and (likely) clothing, recommendations for summer and winter may vary; a suggested typical range for winter is , with that for summer being . Some studies have suggested that thermal comfort preferences of men and women  may differ significantly, with women on average preferring higher ambient temperatures. In the recent past it was common for house temperatures to be kept below the comfort level; a 1978 UK study found average indoor home temperatures to be while Japan in 1980 had median home temperatures of to Health effects. The World Health Organization in 1987 found that comfortable indoor temperatures between were not associated with health risks for healthy adults with appropriate clothing, humidity, and other factors. For infants, elderly, and those with significant health problems, a minimum was recommended. Temperatures lower than with humidity above 65% were  associated with respiratory hazards including allergies. The WHO's 2018 guidelines give a strong recommendation that a minimum of is a "safe and well-balanced indoor temperature to protect the health of general populations during cold seasons", while a higher minimum may be necessary for vulnerable groups including children, the elderly, and people with cardiorespiratory disease and other chronic illnesses. The recommendation regarding risk of exposure to high indoor temperatures is only "conditional". Minimal-risk high temperatures range from about depending on the region, with maximum acceptable temperatures between . Definitions in science and industry. Temperature ranges are defined as "room  temperature" for certain products and processes in industry, science, and consumer goods. For instance, for the shipping and storage of pharmaceuticals, the United States Pharmacopeia-National Formulary (USP-NF) defines "controlled room temperature" as between , with excursions between allowed, provided the mean kinetic temperature does not exceed . The European Pharmacopoeia defines it as being simply , and the Japanese Pharmacopeia defines "ordinary temperature" as , with room temperature being . Merriam-Webster gives as a medical definition a range of as being suitable for human occupancy, and at which laboratory experiments are usually performed.