With well over 3 million residents, Los Angeles is the second-largest city in the United States, only New York City is larger. With towering skyscrapers and picturesque mountains looming in the background, downtown Los Angeles makes for a good photo opportunity. On a clear day, that is. Unfortunately, the air quality in Los Angeles is often less-than desirable! In many instances, Los Angeles has the designation as being the "smog capital of the world". Ah, yes, the good ol' Los Angeles smog; that urban-generated murkiness that hangs in the air like a brown blanket. Nothing destroys - or hides - the Los Angeles skyline better than smog. And Los Angeles has plenty of it. With millions and millions of cars belching and spewing their toxic, gaseous fumes into the air everyday, and with countless refineries and manufacturing plants just adding to the problem, it's amazing that Los Angelenos are still treated to blue skies every now and then. Yes, Los Angeles is well-known for many things - traffic, crime, gangs, e.t.c. - but the one thing that seems to be most associated with Los Angeles is smog! Everybody knows about Los Angeles smog, but what causes it? Why is Los Angeles so cursed with this air pollution problem when so many other big cities throughout the nation are not? Well, there are some very good reasons, actually.
A big contributing factor to Los Angeles being near the top of the nation's smoggiest places - Los Angeles and Houston, Texas, being the two top contenders for the nation's smoggiest city- is climate-related. Los Angeles, for all of its great weather and sunshine, has to put up with something called an inversion layer. A common occurrence in the Summer, a time when Los Angeles experiences its worst air quality, an inversion layer is nothing more than an area of the atmosphere where the normal cooling of air temperature with increasing elevation slows down or even reverses.
Normally, air temperature cools down rapidly as you climb higher and higher up into the atmosphere. With an inversion layer, the air temperature will cool off much slower than normal or the temperature will actually increase as you gain altitude. What this does is cause a layer of warmer air to cover the colder air below it; the inversion layer acts like a lid on whatever is underneath it - in this case air!
What happens is that in a place like Los Angeles, with its 3 million plus residents and millions and millions of cars on the road, all that noxious gas and pollution gets released into the air but upon contact with the inversion layer, the pollution gets trapped; it has nowhere to go! So, instead of dissipating into the upper atmosphere, this "smog" gets stuck in the lower atmosphere where it hangs around the tops of buildings and obscures the many photogenic areas surrounding Los Angeles. The only reprieve is at night when the temperatures cool off enough to break the inversion layer whereby all the pollutants in the air get released into the upper atmosphere.
Another contributing factor that adds to Los Angeles' air quality problem is related to geography. Los Angeles is surrounded by a series of mountain ranges and hills. Many of these mountains reach 10,000 feet in elevation, and combined with the inversion layer, the smog that gets created in Los Angeles gets bottled in; it's capped off on the top by the inversion layer, and the surrounding mountains prevent this smog from dispersing into outlying areas.
The prevailing winds that blow across the Los Angeles area blow from the west to the east, from the Pacific Ocean on the west to the inland valleys to the east, so it's very common for a large amount of downtown Los Angeles smog to be blown out into the interior valleys right up against the mountains slopes.
On bad days, when the temperatures are hot and the air is stagnant, it's often impossible to see the outline of the surrounding mountains until you get within a few miles of them. Many hikers and backpackers standing atop many of the Los Angeles area mountain peaks on bad air quality days are treated to a large brown blanket of haze hovering in the air obscuring their view of the cities and lowlands!
However, on windy days, especially on days when Southern California experiences Santa Ana winds, seasonal type of winds that are known for their strength and velocity, the air in Los Angeles and the surrounding areas is swept crystal clear; the sky is dark blue and one can see for miles and miles in any direction. It's a rare glimpse into what the Los Angeles area sky used to look like before the age of industry and the automobile.
However, as bad as the air quality in Los Angeles can be, it's actually steadily improving. With increased emissions controls and standards being placed on automobiles and industry alike, the level of pollutants being released into the air is slowly being reduced. Although the population of Los Angeles continues to increase, and as a result so does the number of cars on its streets and freeways, the governmental controls and regulations implemented by the Environmental Protection Agency(EPA) continue to make the air in Los Angeles better and better. So, hopefully, in the near future, Los Angeles will be known as something other than the smog capital of the world!