This bill, known as the "Indoor Air Quality and Healthy Schools Act of 2025," aims to establish a comprehensive national program to mitigate health risks associated with exposure to indoor air contaminants. The Environmental Protection Agency (EPA) Administrator is tasked with leading this program, which encompasses assessing, reducing, and preventing exposure to various indoor pollutants across a wide range of buildings, including residences, schools, and commercial facilities. The legislation defines "indoor air contaminant" broadly to include any substance in indoor air that may adversely affect human health. Under this program, the EPA Administrator will carry out several key responsibilities. These include conducting research, providing training and technical assistance on effective monitoring, source control, ventilation, and filtration practices, and ensuring coordination among various federal agencies involved in indoor air quality. A central provision is the requirement for the EPA to establish and maintain a list of indoor contaminants of concern and publish science-based, voluntary guidelines for each. The initial list of contaminants must include particulate matter, carbon monoxide, nitrogen dioxide, ozone, formaldehyde, and radon. These guidelines will offer recommendations for building operation, maintenance, design, and renovation, aiming for significant risk reduction while considering safety and energy factors. Crucially, the guidelines will include recommended health-based concentration limits for contaminants where sufficient scientific evidence exists, with provisions for interim guidelines and regular review and revision. The bill also directs the Administrator to commission a study by the National Academy of Sciences on the feasibility of developing a science-based indoor air quality index to inform the public. Furthermore, it authorizes the EPA to provide financial and technical assistance, including grants, to state, local, and tribal governments, educational agencies, and other entities to develop and implement indoor air quality improvement programs. These programs can address health risks from contaminants, including those exacerbated by climate change, and support the adoption of EPA guidelines. To promote exemplary indoor air quality, the bill establishes a program for voluntary certifications of healthy buildings , requiring adherence to EPA guidelines and the development of indoor air quality management plans. It also mandates the recommendation of model provisions for building design, operation, and maintenance for use in state and local building codes. A significant focus is placed on schools and childcare facilities, requiring a national assessment of indoor air quality in these buildings and ensuring that healthy building certifications are applicable to them. The bill authorizes $100,000,000 for each of fiscal years 2026 through 2030 to fund these initiatives, ensuring that its provisions do not preempt existing state or federal laws but allow for additional voluntary actions.