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Lewiston, Maine, occupies a strategic position within the Androscoggin River Valley, a region historically shaped by industrial activity and agricultural practices. Situated at approximately 44.09°N, 70.16°W, the city’s geography is characterized by a relatively flat terrain, averaging around 170 feet above sea level, gradually rising towards the surrounding hills and forests. The Androscoggin River, a significant waterway, bisects the city, influencing local climate patterns and historically serving as a transportation and industrial artery. Lewiston’s location within the broader New England landscape places it within a transitional zone between the coastal plains and the northern forests. The surrounding landscape is predominantly rural, comprising extensive woodlands, farmland, and smaller towns, creating a distinct urban–rural gradient. Historically, the area supported textile mills, contributing to industrial air pollution in the past, though these have largely diminished. While no major industrial belts directly border Lewiston, the proximity to agricultural zones in surrounding towns can contribute to seasonal particulate matter from farming activities. The city’s position within the valley can also lead to localized air stagnation, particularly during periods of stable atmospheric conditions. The relatively enclosed nature of the valley, coupled with the river’s influence, can trap pollutants, impacting air quality. The climate is humid continental, with cold, snowy winters and warm, humid summers, further influencing pollutant dispersion and accumulation.

Lewiston’s air quality experiences a distinct seasonal cycle heavily influenced by meteorological conditions. Winter months, typically December through February, often present the greatest challenges. Cold temperatures and frequent temperature inversions trap pollutants near the ground, leading to increased concentrations of particulate matter. These inversions occur when a layer of warm air sits above a layer of cold air, preventing vertical mixing and effectively creating a lid on emissions. Snow cover also reduces surface friction, potentially increasing wind speeds and exacerbating the transport of pollutants. Spring (March-May) brings a gradual improvement as temperatures rise and inversions become less frequent, although agricultural activities in surrounding areas can contribute to dust and pollen levels. Summer (June-August) generally offers the best air quality, with warmer temperatures promoting atmospheric mixing and dispersing pollutants. However, occasional heat waves can lead to stagnant air conditions. Fall (September-November) presents a transitional period; cooler temperatures and the onset of leaf decomposition can increase particulate matter, while wind patterns remain variable. Sensitive groups, including children, the elderly, and individuals with respiratory conditions, should be particularly cautious during winter months and periods of agricultural activity. Avoiding strenuous outdoor activity during stagnant air days is advisable. Monitoring local weather forecasts for temperature inversions and wind conditions can help individuals make informed decisions about outdoor exposure. The humid climate can also exacerbate respiratory issues, so staying hydrated and avoiding prolonged exposure to polluted air is crucial.