Is the air we breathe safe?

Is the air we breathe safe? This seemingly straightforward question is often unanswerable because regulations, monitoring approaches, and reporting structures cannot keep up with the rapid human-induced shifts to the planet and atmosphere. The air is becoming more burdened by pollutants from new sources such as intense fires at the wildland-urban interface, an ever-expanding area where human development meets natural habitats. Air pollution is the second leading cause of human death worldwide, a statistic that excludes numerous indoor and acute outdoor exposures. To protect public health everywhere, air quality standards must be modernized, advanced instrumentation mobilized, and collaborative networks established to move air quality assessment into the 21st century.