Canairy — We watch the air. You live your life.

Canairy is a free air-quality app for Android and iOS that combines trusted PurpleAir and government sensor data with the Google Air Quality API — plain-English verdicts, smart alerts, and trends for every place you care about.

Canairy is built by two parents in Sonoma County, California, who got tired of guessing whether it was safe to send the kids outside. Why we built it.

• Real-time air quality for every place you care about, from trusted PurpleAir and government sensors.
• Plain-English verdicts — what the number means and what to do about it.
• Smart alerts by SMS and push when the air crosses your threshold, plus predictive "air will worsen" heads-ups.
• Trends that show when and where your air is worst.

From the air quality guide

• How to Read the Air Quality Index — The AQI is the number you see in every weather app and on every air quality monitor. Knowing what it means takes about two minutes and changes the decisions you make on bad air days.
• Wildfire Smoke — Wildfire smoke is a mix of gases and fine particles released when vegetation, structures, and soil burn. The dominant pollutant by health risk is PM2.5: fine particles small enough to lodge deep in the lungs and cross into the bloodstream.
• Asthma and Air Quality — About 25 million Americans have asthma, including roughly 5 million children. For most of them, air quality is one of the biggest day-to-day variables in how their lungs feel. A bad-air day can mean wheezing, missed work or school, an ER visit, or worse.
• Best Time of Day to Exercise Outside — Outdoor exercise doubles or triples your breathing rate, which means you pull in more of whatever is in the air. Picking the right hour can cut your dose substantially without changing your training.
• HEPA Air Purifiers: What to Look For — A good HEPA purifier can drop indoor PM2.5 by 50% to 80% within an hour. A bad one is an expensive nightlight. Three numbers and one filter type tell you most of what you need to know.
• Air Pollution and Children's Health — The World Health Organization estimates that 93 percent of children under 15 worldwide (about 1.8 billion kids) breathe air dirty enough to threaten their health and development. In 2016, polluted air contributed to roughly 600,000 child deaths from lower respiratory infections.

Get Canairy free on Google Play and the App Store.