RELEASE: Knozone Action Day Called for Wednesday Due to High Ground-Level Ozone, "Unhealthy for Sensitive Groups"

Knozone Action Day Called For Wednesday Due to High Ground-Level Ozone, 'Unhealthy for Sensitive Groups'

People in Central Indiana with asthma, COPD, and many other diagnoses should avoid time spent outdoors Wednesday, July 23 due to high ground-level ozone forecast
 

INDIANAPOLIS—The Indianapolis Office of Sustainability is issuing a Knozone Action Day for sensitive groups (orange on the Air Quality Index, included below) for Wednesday, July 23. Above average temperatures, sunny skies, and some light wildfire smoke are expected tomorrow as high pressure settles in over the Central Indiana region that will lead to conditions suitable for ozone development. Sensitive groups should remain indoors on Wednesday as much as possible. This is the fourth Knozone Action Day declared so far in 2025.

Unhealthy air quality impacts public health and environmental injustice as vulnerable groups including children, older adults, pregnant people, outdoor laborers, and anyone suffering from asthma, COPD, emphysema, heart disease, or other conditions are at greater risk. Nearly 1 in 5 Marion County community members is at greater risk for severe symptoms due to unhealthy air quality.

City officials will be distributing informational materials on air quality and extreme heat at the "Ask the City" booth at The Original Farmers' Market on Monument Circle tomorrow from 11 a.m. to 1 p.m.

Community members can sign up for text or email alerts at smogwatch.in.gov to be notified of unhealthy air days early. Knozone.com and the EPA's AirNow website  and mobile app are other great resources for monitoring local air. Community members can also follow @SustainIndy on Facebook, X, and Instagram for reminders about Knozone Action Days.

To protect residents and local air quality, the Office of Sustainability issues Knozone Action Days when levels of certain pollutants rise above acceptable thresholds. During Knozone Action Days, the air quality may become unhealthy for sensitive individuals due to increased ground-level ozone and/or fine particles -- two of the most common pollutants in the United States.

While the ozone layer high in the atmosphere helps protect us from the sun’s rays, ozone down where we breathe is dangerous for public health. Ground-level ozone is created when a chemical reaction occurs between sunlight and hydrocarbons from emission sources common in urban areas, like gas-powered vehicles and lawn mowers. Fine particulate matter (or PM2.5) refers to microscopic particles in the air, including dust and smoke, that we can inhale into our lungs and cause damage. This can even be caused by wildfires or dust clouds blowing from thousands of miles away.

Every day, and especially on Knozone Action Days, residents are encouraged to reduce their contribution to ground-level ozone through these simple actions:

  • Avoid vehicle idling, including when in drive-thru lanes or picking up carry-out

  • Drive less: use active forms of transportation like walking or biking (utilizing Pacers Bikeshare's IndyRides Free pass!)

  • Utilize public transportation or carpool with services such as IndyGo or Commuter Connect

  • Wait to refuel and use gas-powered lawn equipment until temperatures are cooler

  • Combine errands to reduce number of trips

  • Conserve energy by turning off lights or setting the air conditioner to 75 degrees or above

  • Delay use of garden, household, and workshop chemicals until air has returned to healthy levels

For more information on how to help improve Central Indiana’s air quality, visit https://knozone.com/actionday.
 

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Lindsay Trameri