Mount Vernon Air Quality Index (AQI)

Loading live AQI data...

Loading historical AQI trends...

Mount Vernon, Illinois, sits within the expansive, gently rolling plains of the Midwestern United States, specifically in the heart of the Little Wabash River Valley. Located at coordinates 38.3140° N, 88.9174° W, the city’s terrain is characterized by relatively flat agricultural land, dissected by the waterways that define the region. The elevation is modest, around 459 feet above sea level, contributing to limited natural air dispersion. Mount Vernon functions as a regional hub for Jefferson County, serving surrounding rural agricultural communities. Its location isn’t directly adjacent to the Great Lakes, but receives moisture-laden air masses from them, influencing local weather patterns. Historically, the area’s economy was heavily reliant on coal mining, and while diminished, remnants of this industrial past, alongside ongoing agricultural activity (primarily corn and soybean farming), contribute to potential air quality concerns. The urban-rural gradient is pronounced; the city itself is a concentrated source of emissions, while surrounding areas are dominated by diffuse agricultural sources like fertilizer application and livestock operations. The Little Wabash River, while providing scenic value, can also contribute to localized humidity and potential for temperature inversions, trapping pollutants near the ground. This geographic setting dictates the types of pollutants and their dispersion patterns in Mount Vernon.

Mount Vernon experiences a distinct four-season climate, profoundly impacting its air quality. Spring (March-May) often sees elevated particulate matter from agricultural practices – tilling fields and fertilizer application – combined with pollen. Winds can be variable, sometimes failing to adequately disperse these pollutants. Summer (June-August) brings warmer temperatures and increased ozone formation, particularly on stagnant, sunny days. The humidity from the Little Wabash River can exacerbate this. August often presents the highest ozone levels. Fall (September-November) is generally the period of best air quality, with cooler temperatures and reduced agricultural activity. However, burning of agricultural residue can briefly degrade air quality. Winter (December-February) is characterized by cold temperatures and potential for temperature inversions, trapping pollutants from residential heating (wood burning is common) and vehicle emissions near the ground. January and February are typically the months with the poorest air quality. Sensitive groups – children, the elderly, and those with respiratory conditions – should limit strenuous outdoor activity during peak pollution periods in spring, summer, and winter. Monitoring local forecasts and adjusting activity levels accordingly is crucial for protecting health.