Data: EPA AirNow, FEMA National Risk Index Last verified: 2026-07-18

What is AQI?

The Air Quality Index (AQI) is a standardized scale from 0 to 500 that measures air pollution levels. 0-50 is "Good," 51-100 is "Moderate," 101-150 is "Unhealthy for Sensitive Groups," and above 150 is "Unhealthy" for everyone. AQI tracks five major pollutants: ground-level ozone, particulate matter (PM2.5 and PM10), carbon monoxide, sulfur dioxide, and nitrogen dioxide. Marengo's average AQI of 58 falls in the "Moderate" range.

Air Quality by ZIP Code in Marengo

Marengo is covered by a single ZIP code, so one AQI profile applies citywide. Air quality still shifts with wind, season and proximity to pollution sources.

ZIP Code	AQI	Category	Wildfire	Mold
60152	58	Moderate	6	49	View report →

Air Quality Overview

Marengo, Illinois has moderate air quality with an average AQI of 58. Air quality is acceptable, though some pollutants may be a concern for a small number of people who are unusually sensitive to air pollution. The dominant pollutant is Ozone.

The Air Quality Index (AQI) is an EPA-standardized scale from 0 to 500. Values below 50 are "Good," 51-100 "Moderate," 101-150 "Unhealthy for Sensitive Groups," 151-200 "Unhealthy," 201-300 "Very Unhealthy," and above 300 "Hazardous."

Dominant Pollutant: Ozone

Ground-level ozone forms when pollutants from cars, power plants, and industrial facilities react with sunlight. Unlike stratospheric ozone, ground-level ozone is harmful to breathe.

Health effects of ozone exposure:

• Irritation of the respiratory system
• Reduced lung function
• Aggravation of asthma and chronic lung diseases
• Increased susceptibility to respiratory infections

Peak times: Ozone levels are typically highest on hot, sunny afternoons. Exercise outdoors in the morning when levels are lower.

Air Quality by ZIP Code in Marengo

AQI varies across Marengo's 1 ZIP code based on proximity to pollution sources, traffic patterns, and local geography:

Wildfire Smoke Risk

Marengo has a low wildfire smoke risk with an average smoke risk score of 6 (scale 0-100). However, smoke from distant wildfires can temporarily degrade air quality even in low-risk areas.

Metric	Value
Avg. smoke risk score	6
Max smoke risk score	6
Fires within 100 km	0
High-risk ZIP codes	0

Wildfire smoke contains PM2.5, carbon monoxide, and volatile organic compounds. Even short-term exposure can trigger asthma attacks and respiratory distress.

Indoor Mold Risk

Marengo has an average mold risk score of 49 out of 100.

Factor	Value
Mold risk score	49/100
Average humidity	68% RH
High-risk ZIPs	0
Peak season	summer high

Mold risk is influenced by humidity levels, housing age (older homes have more moisture issues), flood history, and water infrastructure quality. Indoor humidity above 60% creates favorable conditions for mold growth.

Signs of mold problems: musty odors, visible growth on walls or ceilings, worsening allergies indoors, condensation on windows. Professional mold testing ($300-$600) can identify hidden issues.

Health Recommendations

With moderate air quality (AQI 58), most people can be active outdoors. Sensitive groups should take precautions:

• Sensitive groups (asthma, COPD, heart disease): consider reducing prolonged outdoor exertion
• Keep windows closed on high-pollution days
• Use a HEPA air purifier in main living areas
• Check AirNow.gov before outdoor exercise

Marengo vs. Nearby Illinois Cities

How Marengo's air quality compares to nearby cities:

ZIP Codes in Marengo

Marengo covers 1 ZIP code. Air quality can vary by neighborhood based on proximity to highways, industrial areas, and green spaces. Check your specific ZIP code for localized data.

Data Sources

• Air quality: EPA AirNow - real-time and historical AQI data
• Wildfire risk: FEMA National Risk Index
• Mold risk: Derived from EPA, FEMA, Census ACS (humidity, housing age, flood history)
• Monthly AQI: EPA Air Quality Statistics

Updated daily.