Indoor air quality and its effects on humans-A review of challenges and developments in the last 30 years

A reflective approach is adopted in analyzing the reviews on the impact of indoor air quality on humans over the last 30 years (1986-2016). The major findings reiterate the concerns of indoor air pollution (IAP) and provide a deeper understanding of how contaminants contribute to, and interact to accentuate the adverse effects on humans. Issues which have emerged and increased in importance are indoor chemistry, airborne infection, and the impact on performance. Societal trends of rising affluence of the middle class, increased population density in cities, introduction of new synthetic materials, reliance on childcare facilities have led to greater intensity of exposure to IAP. Responses to climate change, energy conservation and singular strategies to manage the complex challenge of IAP have not been effective in alleviating the deterioration of indoor air quality. Innovations in air distribution, air cleaning, modularization of indoor environmental devices/systems, and leveraging on smart technologies and sensing systems which incorporate algorithms that optimizes indoor air quality with conventional performance indicators are important advancements towards a holistic solution. User engagement, both as a sensor and indicator of preferences, when integrated with such innovations, may usher in the next important paradigm towards achieving acceptable indoor environmental quality beyond the current definitions of acceptability from population-based criteria to one that embraces the individual on an as-needed, when-needed and as-preferred basis.