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Hazy Winter Air

Dec 03, 2014 | Read More News
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Why does the morning sky look hazy?

Meteorologists call this phenomenon a temperature inversion. It’s what happens when nighttime and early morning temperatures drop, trapping pollutants in the calm morning air. Warm air above the cool surface air traps the polluted air close to the ground, and keeps it from rising.

That’s what causes the visible haze, as airborne pollutants hang closer to ground level. But as the sun rises and the cool air warms, the hazy air begins to rise, carrying airborne pollutants with it. The hazy air moves higher and higher, dispersing the pollution as itInversion and Pollution Cause Hazy Air goes and improving visibility.

This often yellow-brownish haze occurs mostly in winter, when nights are longer and the air stays cool until the sun rises up over the mountains to begin warming the air and earth. Tucson is surrounded by mountains, and they contribute to the winter inversions. The mountains cause an overnight downward flow of cold air onto the desert floor, and that cold air can increase the strength and duration of these morning temperature inversions.

What this means is that air quality and visibility can be poorer in winter because pollutants from motor vehicles, industry and fireplaces remain trapped longer in the air we breathe. These very small particles, called particulate matter (PM), can penetrate deep into the respiratory system and are harmful to breathe. Recent studies indicate that PM can have the following effects on our bodies:

  • causes lung irritation, which leads to increased permeability in lung tissue. 
  • aggravates the severity of chronic lung diseases, causing rapid loss of airway function. 
  • causes inflammation of lung tissue, resulting in a chemical release that can impact the heart. 
  • causes changes in blood chemistry that can result in clots that may lead to heart attacks. 
  • increases susceptibility to viral and bacterial pathogens leading to pneumonia in vulnerable persons who are unable to clear these infections.

We can help reduce winter air pollution levels by driving less often, idling our vehicles no more than a minute and reducing our use of wood-burning fireplaces. Fireplaces are inefficient sources of heat. When you have the option, choose natural gas, electric or solar-powered heat, or a wood stove certified by the Environmental Protection Agency.

To reduce your use of polluting fossil fuels, carpool, ride a bike, or take the bus if you can, pick a “no-drive” day each week, and do more than one errand while out in your vehicle to reduce the number of trips you make.

For more on local air pollution levels in Tucson, including particulates, ozone and carbon monoxide readings, visit the Air Monitoring section of this website.