Although indoor air is mentioned by several writers over the last two centuries – and even by some ancient writers - most modern concerns of indoor air quality (IAQ) began in the 1970s (ASHRAE Standard 62) and 1980s (1st ASHRAE IAQ conference 1986). Standard 62 is a proactive approach but most other work dealing with IAQ was in reaction to IAQ complaints. The accumulated experience of many workers identified several issues that collectively cause most of the common IAQ problems. This laid the basis for recognizing and correcting most IAQ problems, but after the problem occurred. More recently, proactive programs or parts of programs sought to lower the chances of IAQ problems, but as only one of several topics (energy and water use, materials, sites, etc). Perhaps best known is the indoor environment portion of LEED, but rating systems in Asia, the Middle East and other areas also include IAQ protective elements. These systems usually emphasize design elements and construction though, rather than performance during occupancy. A proactive scheme is available that relies on occupants rather than specialists for an assessment and is specifically tailored for schools.Regional and international plans have been recently introduced that emphasize performance rather than design (SS554, GB/T18883) but address the impact on people as only one of several environmental features. Another recent program (WELL) centers on occupants but includes several non-IAQ issues and another program focuses on IAQ (rather than multiple aspects) and on the performance (rather than design) of the building during ongoing occupancy (rather than only at completion of construction/renovation).Each program contains proactive components for IAQ. This contrasts with the routine attention to IAQ in past decades which almost invariably reacted to complaints. The emphasis on moisture in buildings is prominent in several of the programs which will be beneficial in most tropical areas of the world as well as humid or severe climates in non-tropical areas. The rapidity with which these programs have been introduced and are being accepted indicates that building owners, operators and occupants are realizing the benefits of good IAQ.