What is a primary reason for increased carbon monoxide accumulation from October through March?

The accumulation of carbon monoxide from October through March is primarily attributed to calmer weather conditions that lead to the formation of inversion layers. During the colder months, especially in areas with significant temperature differences between the ground and the upper atmosphere, temperature inversions can occur.

An inversion layer traps cooler air close to the ground, preventing it from dispersing. This stagnant air can accumulate pollutants like carbon monoxide, which is often emitted from vehicles and heating systems. The lack of wind during this period contributes to the persistence of these pollutants in the air.

In contrast, other factors may not significantly influence carbon monoxide levels during these months. For instance, while increased vehicle usage can contribute to higher emissions, this is not as impactful as the meteorological conditions that prevent dispersion. Additionally, industrial activity can vary but is not typically a seasonal driver for carbon monoxide in the same consistent way as weather conditions.

Overall, the combination of lower temperatures, reduced wind, and the presence of inversion layers creates an environment conducive to carbon monoxide accumulation during the fall and winter months.