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Chí Linh occupies a strategic position in the northernmost part of Hải Dương Province, serving as a transition zone between the flat, alluvial plains of the Red River Delta and the rolling foothills of the Dong Trieu mountain range. This undulating terrain creates a unique urban character, where pockets of dense residential development are interspersed with limestone outcrops and lush agricultural landscapes. The city's geography is defined by its proximity to the Thái Bình River basin, which provides essential irrigation for the surrounding rice paddies and fruit orchards. However, this specific topography significantly influences local air quality; the surrounding hills can act as physical barriers, occasionally trapping pollutants within the valley during periods of atmospheric stability. The regional economy is heavily influenced by the industrial belt, particularly the historical legacy of coal mining and the presence of cement production facilities. These industrial activities, combined with the urban–rural gradient, introduce particulate matter and sulfur dioxide into the atmosphere. Because the city is nestled against the highlands, the wind flow is often channeled through valleys, which can either flush out pollutants or concentrate them depending on the wind direction. The intersection of heavy industry and a fragile natural ecosystem makes Chí Linh a critical point for monitoring the interplay between economic growth and environmental health, as the rural periphery struggles to buffer the industrial emissions generated within the urban core. Furthermore, the city's elevation variations create microclimates that further complicate the dispersion of smog during the colder months of the year.

In Chí Linh, air quality fluctuates dramatically across the four seasons, driven primarily by the East Asian monsoon system. During the winter months, from November to February, the region experiences the Northeast monsoon, bringing cool, dry air. This period is often characterized by temperature inversions, where a layer of warm air traps colder, polluted air near the ground, leading to peaks in particulate matter. Dense winter fog frequently exacerbates this, reducing visibility and concentrating industrial emissions from coal and cement plants. Consequently, sensitive groups, including children and the elderly, should limit outdoor exertion during these stagnant mornings. As spring arrives in March and April, the weather becomes more volatile, with increased humidity and occasional storms that help scrub the atmosphere, leading to a temporary improvement in air quality. The summer months, from May to August, are dominated by the Southwest monsoon, which brings heavy rainfall and higher temperatures. These rains provide a natural cleansing effect, washing pollutants from the air, although high humidity can increase the feeling of atmospheric heaviness. Autumn, from September to October, serves as a transition period where air quality remains relatively stable, making it the most favorable time for outdoor activities. However, the practice of agricultural residue burning in the rural outskirts during harvest transitions can cause sporadic spikes in smoke. Health professionals recommend using air purifiers during winter peaks and staying hydrated during the humid summer to mitigate respiratory stress. Vigilance is essential for those with asthma when the winter smog settles deep into the city's valley.