The sustainability of egg production has been challenged by significant losses caused by infectious diseases and heat stress due to frequent and intense heat waves linked to climate change. Infectious diseases have been a constant problem for the U.S. layer industry. Highly Pathogenic Avian Influenza (HPAI) is one of these airborne pathogens and has had two major outbreaks in the U.S. in the last decade alone: the 2014-1/1/201522 outbreaks with 57 million and 57.6 million infected birds, respectively, costing the industry and taxpayers billions of dollars. In addition to HPAI, the incidence of other respiratory diseases can increase due to environmental factors leading to stress, and, consequently, immunosuppression, giving pathogens opportunities to cause diseases. Best management practices such as biosecurity, vaccinations, and chemical disinfectants have been developed and implemented to prevent outbreaks the diseases. However, while mostly effective, they cannot stop the spread of the infectious diseases because some pathogens are airborne and transmitted in airflow and into a building through the ventilation system. Hence, prevention of HPAI and other infectious diseases can only be accomplished by enhancing the general health of layers via better understanding of the environmental conditions and control strategies that prevent diseases.The mandatory conversion of 66% hen inventory from conventional caged to cage-free housing by 2026 are worsening the above challenges. Indoor environmental quality (IEQ) inside layer houses directly affects the respiratory system of layers. Elevated ammonia and dust levels have been known to enhance the incidence of respiratory diseases in caged layers. The current cage-free laying hen housing systems are 7-8 times dustier, emit higher levels of ammonia, and enrich more pathogens in comparison with the conventional caged systems. Ventilation systems play an important role to ensure the general health of layers by removing excessive heat, moisture, air pollutants, and airborne pathogens in poultry facilities. However, the typical ventilation systems adopted in current poultry houses, including cross and tunnel ventilation systems, have difficulties in limiting transmission of diseases while maintaining a comfortable and uniform thermal environment. Thus, a holistic, innovative, and forward-thinking approach is warranted for us to develop effective and proactive strategies for sustained layer health in the context of housing environment, heat stress, infectious diseases, social acceptance, productivity, as well as sustainability. The egg industry is in need of effective interventions and innovative environmental quality control technologies to sustain health and improve production efficiency.Our long-term goal is to improve hen health and performance by effective indoor environmental quality interventions and an innovative ventilation and air-conditioning system through a multidisciplinary team collaboration that converges the sciences and engineering technologies in animal health, animal production, and indoor environmental quality control.The specific objectives are:1. Utilize the established university and egg industry partnerships to reach out to cage-free egg producers to learn their management challenges and needs for research and education to improve hen health and production efficiency.The project team will work with the Egg Industry Center (EIC) and its stakeholders, including the American Egg Board (AEB), and the United Egg Producers (UEP), and the U.S. Roundtable for Sustainable Poultry & Egg (US-RSPE), to identify cage-free egg producers' challenges and education needs to improve poultry health and performance.2. Assess the impacts of cage-free housing environments on microbiota, immune development, disease susceptibility and transmission, and bird performance.Using both commercial farms and a controlled environment research farm, we will comprehensively assess the impacts of various cage-free housing environments on microbiota, immune development, disease susceptibility and transmission, and bird performance.3. Development of an Upward Airflow Displacement Ventilation (UADV) for cage-free layer housing to abate heat stress and disease transmission. Computational Fluid Dynamic (CFD) simulation will be used to modify a UADV system developed for caged housing  for its applications in cage-free layer houses. For extremely hot weather conditions, fresh air can be cooled using energy-efficient air conditioning (e.g. ground-coupled/geothermal systems) prior to entry into the bird occupied zone. A small prototype of the ventilation system will be built at the OSU Poultry Research Center and its capabilities on control of indoor thermal environment and disease transmission will be tested.4. Disseminate the advanced IEQ intervention strategies and technologies to the current and future egg industry workforce.We will develop (1) workshops and demonstrations for egg producers on innovative IEQ control interventions for improved health, feed efficiency, production efficiency, and sustainability; and (2) a new multidisciplinary seminar course for college students on advanced management strategies and indoor environmental control technologies to sustain poultry health and performance in the new emerging cage-free housing.