Winter Air Pollution: Understanding Seasonal Impact
Published on December 12, 2024
While summer smog often grabs headlines, winter air pollution poses its own set of challenges, affecting both public health and the environment. Colorado's geography, weather patterns, and human activity all contribute to a unique set of conditions that exacerbate air pollution during the colder months.
Where Does Winter Air Pollution Come From?
One of the biggest culprits of winter air pollution is the temperature inversion phenomenon. Under normal conditions, air near the ground is warmer and rises, dispersing pollutants. In winter, however, cooler air gets trapped beneath a layer of warmer air, effectively creating a "lid" that prevents pollutants from escaping into the atmosphere. These inversions are common in the Denver Metro and northern Colorado regions, where mountains can act as natural basins for pollution, making it harder for pollutants to disperse, especially during stagnant weather patterns.
The winter months also show a steep increase vehicle idling as drivers warm up their cars and colder temperatures. This can cause engines to burn fuel longer and less efficiently, leading to higher emissions. Additionally, the chemicals and sand used to keep roads safe during icy conditions can contribute to air quality issues. Sand particles can become airborne, while the breakdown of de-icing agents can release pollutants.
Understanding Action Day Alerts
The Winter High Pollution Advisory Program is coordinated by the Air Pollution Control Division of the Colorado Department of Public Health and Environment and are issued daily from October 31 through March 31 at 4 p.m. When conditions warrant, forecasts will include information about Action Days and subsequent indoor burning restrictions for the seven-county Denver-Boulder metropolitan area only.
An Action Day for fine particulates, carbon monoxide or ozone indicates that either current air quality is unhealthy, or conditions are expected to worsen later in the day or on the next day. Action Days for air pollutants generally indicate that air quality will be in either the Unhealthy or Unhealthy-for-Sensitive-Groups categories according to the Air Quality Index
When no advisories are issued, air quality is good or moderate and is expected to remain so during the effective period of the forecast. No restrictions are in place.
Staying Informed
Residents can stay updated on current air quality conditions and advisories by visiting the CDPHE's Air Quality Advisory page.