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Fukuyama, situated in Hiroshima Prefecture along Japan's Seto Inland Sea coast, occupies a distinctive geographic position that significantly influences its air quality patterns. The city lies on the southern edge of the Chūgoku Mountains, creating a natural topographic barrier to the north, while opening southward to the Seto Inland Sea—a semi-enclosed body of water that moderates local climate but can trap pollutants under certain conditions. Fukuyama's urban core sits at low elevation near sea level, with gradual rises toward northern suburban and rural areas, establishing a clear urban-rural gradient. This coastal plain location places Fukuyama within Japan's industrial heartland, with proximity to manufacturing zones in the Setouchi Industrial Region, though the city itself maintains a balanced mix of light industry, commerce, and residential development. The surrounding landscape features agricultural zones in the hinterlands, particularly rice paddies and citrus orchards, which can contribute seasonal agricultural emissions. Fukuyama's position along major transportation corridors, including the Sanyo Shinkansen line and coastal highways, adds mobile pollution sources. The city's geography creates a microclimate where sea breezes from the Seto Inland Sea typically disperse pollutants during daytime, but nighttime land breezes can occasionally concentrate emissions from urban and industrial sources along the coastal fringe, particularly during stable atmospheric conditions.

Fukuyama's air quality follows distinct seasonal patterns shaped by regional meteorology and local emissions. Spring (March-May) brings generally good air quality as increasing temperatures and frequent sea breezes from the Seto Inland Sea disperse pollutants effectively; however, late spring can see occasional haze from Asian dust (kosa) events carried by westerly winds from continental Asia. Summer (June-August) offers the cleanest air overall, with prevailing southerly monsoon winds from the Pacific Ocean providing excellent ventilation, though high humidity and temperature can occasionally trap ground-level ozone precursors from urban emissions. Autumn (September-November) begins with continued good dispersion but transitions to more variable conditions as temperatures drop and atmospheric stability increases; October and November may see occasional temperature inversions in early morning hours that temporarily elevate particulate concentrations. Winter (December-February) presents the most challenging season for air quality, with frequent temperature inversions developing in the Seto Inland Sea basin, particularly during calm, clear nights when cold air drains from the Chūgoku Mountains and becomes trapped under warmer air aloft. These inversion layers can concentrate pollutants from heating sources and urban emissions, with January and February typically showing the highest pollution levels. Sensitive groups should monitor air quality forecasts particularly during winter mornings and during spring dust events, scheduling outdoor activities for midday when dispersion is best.