Wildfire season has arrived, bringing orange-tinted skies and hazardous air quality to millions of people across the country. Just this past week, wildfires spread across parts of Arizona, including near the Grand Canyon. In June, smoke from Canadian wildfires blanketed a third of the U.S., triggering air quality alerts in multiple regions. While wildfire smoke has become a familiar seasonal issue, it also highlights a more persistent and less visible threat that affects us year-round: the quality of air we breathe indoors. 

Indoor air quality is essential to our health. Yet despite spending 90% of our time indoors, there are no enforced health-based standards for indoor air. While we tend to focus on outdoor air pollution, the air we breathe inside our buildings can be just as harmful. It affects how we think, how we feel, and whether we get sick. Poor indoor air can trigger asthma, spread respiratory infections, and affect our ability to focus and function throughout the day. 

Wildfire smoke serves as a clear, visible reminder to take action for cleaner indoor air. When wildfire smoke moves into a community, residents are advised to close windows, use air purifiers, and turn on the mechanical ventilation system if available. The goal of these actions is to keep smoke out, filter air flowing into the building, and prevent harmful particles from entering our lungs. But these protective measures shouldn’t be limited to wildfire season—we should be taking steps for cleaner indoor air everyday. 

Though often invisible, indoor pollutants pose significant threats. Wildfire smoke—containing harmful, microscopic particles that can enter a person’s bloodstream—can seep into our homes, making our indoor air hazardous. Many sources of indoor pollutants also come from inside our buildings, such as fuel-burning combustion appliances and building materials. These sources can release harmful substances into the air, including carbon monoxide, volatile organic compounds, and asbestos. Without adequate ventilation, these pollutants, along with dust, allergens, and airborne viruses, can accumulate to unsafe levels. Alarmingly, indoor air often contains pollutant concentrations two to five times higher than outdoor air, highlighting the invisible risks we face even inside our own homes, schools, and workplaces. 

This has significant impacts on our health. 

Both short and long term exposure to indoor air pollution has been linked to respiratory and cardiovascular diseases, an increased risk of certain cancers, and even reduced productivity and performance. In classrooms, for example, low ventilation rates reduce students’ attention and test scores. Improving air quality and ventilation can boost children’s performance in schools by as much as 30% and reduce student absenteeism by over 12%. Similarly, employees in offices with cleaner air have performed more than twice as well on cognitive tests. 

Indoor air quality also plays a critical role in the spread of respiratory viruses. Because airborne viruses spread more easily indoors, improving ventilation can reduce disease transmission by up to 80%. Just as air filters can capture smoke and allergen particles, high quality filters can also capture airborne viruses. Bringing in clean outdoor air can further dilute harmful air. One study found that improving ventilation in schools to recommended levels was as effective at preventing the flu as vaccinating 50-60% of those in the school community. 

Given these clear health impacts, we must ensure clean indoor air in all buildings and communities. Several states have taken legislative action. For example, Connecticut requires school districts to evaluate indoor air quality annually and inspect each school’s HVAC system every five years. Rhode Island introduced a similar bill to improve indoor air quality in schools.

However, more action is needed to ensure we have healthy indoor air in all spaces. 

Minimum health-based standards for indoor air quality should be established for all public buildings, especially classrooms. Legislation could require the implementation of  these standards and provide funding for upgrades in schools. State and federal public health agencies could also issue alerts and guidance during flu season and other increased periods of respiratory illnesses, informing the public on steps to improve indoor air quality. This includes opening windows or using an air purifier, which can help reduce the spread of disease. Continued public health campaigns and outreach can build greater awareness of the dangers of poor indoor air quality in the community as well.

As wildfire season reminds us of the importance of air quality, we can no longer ignore the invisible dangers inside our buildings. It’s time we make clean indoor air a national public health priority.