You don’t need us to tell you it's hot out there, LOU — just step outside and let your glasses fog up.

However, something you might not have noticed as sweat drips down your forehead are the city’s Air Quality Alerts.

Let's unpack these alerts, how to track them + what you can do to help.

Air Quality Alerts are issued based on the Air Quality Index (AQI), which tells us the cleanliness of outdoor air. While there are five major air pollutants, the two that Louisville Metro’s Air Pollution Control District (APCD) is most concerned with are ground-level ozone and particle pollution.

Ground-level ozone (O3): This is not emitted directly in the air. It's created when other pollutants — such as vehicle + industry emissions — mix with heat and sunlight. This makes the pollutant more prevalent in the summer months.
Particulate matter (PM10 + PM 2.5): This is composed of super small, solid particles and droplets suspended in the air. It comes from a variety of components like metals, soil, dust + organic chemicals.

The APCD monitors and predicts these pollutants via ten air stations across the Greater Louisville area.

AQI is metered from zero-500 and uses six color variations to denote how hazardous the air is for our health.

For example, if Derby City receives a yellow rating of 99, it would mean it's a good day to be outside for just about everyone except those considered to be part of sensitive populations.

Yesterday's AQI was 99. | Screenshot from Louisville’s Air Quality Index

Much like the weather, air quality can be forecasted. See Louisville’s Air Quality Index or sign up to receive alerts via email to learn what the daily status means for you.

Help improve our air quality by reducing unnecessary engine idling, switching to electric-powered lawn equipment, and reading Kentuckiana Air Education’s clean air tips.