TALES OF OUR TIMES: Why Hazy Days Are Hazy

Tales of Our Times
By JOHN BARTLIT
New Mexico Citizens
for Clean Air & Water

Why Hazy Days are Hazy

Why is hazy air hazy? A 5¢ question with a $50 answer. Today’s story is the $3.98 version in three parts—physics, weather conditions and human actions.
    
The chapter on physics tells us that hazy air has more fine particles in it than clear air.  “Fine particles” are very small bits of solids or liquids, so small they stay in the air without settling.
    
And so small they “scatter” a lot of light. That is, they “knock it away,” so less light gets from out there to your eye. Out there may be the sights of Black Mesa, the Sangre De Cristos and Grand Canyon National Park.
    
The more particles are in the air, the more light is scattered. The more scattering, the more haze. The more haze, the less far you can see and the more washed out (the more gray) are the colors you see. Or rather, the grayer are the colors you don’t see. 
    
That is physics. It can spoil your whole day, your vacation and your property values.
    
So what kinds of particles are in the air, and who put them there in the first place? The weather sporadically makes particles and transports them, sometimes for long distances.
 
Natural particles include fog, windblown dust, smoke from natural fires, even sea salt. Nature herself causes some days every year to be hazy. She did it long before Coronado toured the Sunbelt, and after the shallow seas were gone.  
 
Our region’s peculiar dryness makes the natural, historically-prized visibility in the Southwest close to the clearest in the world on an average day.
 
Then human actions come in. A variety of human workings create particles (thus haze) that reduce visibility below this natural daily average. New Mexico Citizens for Clean Air & Water first was formed and fired up over some of the grosser human outpourings—the Four Corners Power Plant of the 1960s, the Kennecott copper smelter near Silver City and the Duke City sawmill’s smoking “tepee” burner near Española.
 
Lengthy efforts made big improvements in these sources.
Into the 1980s, these three human activities dumped wastes into the air by the ton and hundreds of tons daily that chronically hurt long-range visibility.
 
Large operations—like one dirty power plant or smelter—can spread haze every day over hundreds of miles, in different directions on different days. 
 
The two worst emissions for wasting vistas are ash (smoke) and sulfur dioxide (SO2).  Smoke comes directly as tiny particles, whether round ones (from power plants) or jagged ones (from tepee burners).
 
SO2 from power plants, refineries and smelters is a colorless gas that reacts in the atmosphere to produce the particles that can turn azure-framed, orange-red mesas into ghosts. Nitrogen oxides (NOx) rank third as haze-makers from industry.
 
The superflood of cars and trucks in cities also emits several gases that produce particles and haze. The two worst are hydrocarbon gases, called Volatile Organic Compounds or VOCs, and NOx. 
 
Next on the bad list is soot, mainly carbon, from diesels and fireplaces. Visibility is not harmed by common carbon monoxide (CO), an invisible pollutant from cars that works its witchery against health.
 
So why is a hazy day hazy? On any given day, no one can say for sure without physically analyzing the particles in the air.
 
On days overall, Southwestern vistas are not as hazy now as they were in the 1970s, but also are measurably hazier now than in eras before then.
Human activities, driven by human nature, make these changes in the course of time. Industrial sources, led by power plants, rank No. 1 in humans’ haze-making; vehicles are No. 2. 

 
The villains are those repulsive little particles that scatter away light. 
 
Enchantment, call thee fragile.
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