Photochemical Smog

Have you ever been in the city and catch yourself coughing or breathing more heavily than usual? Photochemical smog is a silent but deadly enemy. We don't notice it, but it's all around us, especially in cities and heavily populated areas. The problem of photochemical smog should be addressed and people should be made aware of its risks and how we can prevent this from getting worse.

What is Photochemical Smog?

Photochemical smog is a unique type of air pollution which is caused by reactions between sunlight and pollutants like hydrocarbons and nitrogen dioxide.

Some of the particulate matter in the air can oxidize very readily when exposed to the UV spectrum. Nitrogen dioxide and various hydrocarbons produced through combustion will interact with sunlight to break down into hazardous chemicals. It doesn't have to be sunny for photochemical smog to form; UV light can also penetrate clouds.

Primary pollutants, which include sulfur dioxide,carbon monoxide, and other volatile organic compounds compounds, are introduced into the atmosphere via vehicular emissions and industrial processes.

Secondary pollutants, like ozone and hydrocarbons, result from the reaction of primary pollutants with ultraviolet light.

The mixture of these primary and secondary pollutants forms photochemical smog.

How does this affect us?

While ozone is an excellent thing in the upper atmosphere, since it protects the delicate environment of the Earth, it is not desired at ground level. Ozone can be extremely irritating to the respiratory tract, leading to fits of coughing and various medical conditions if exposure is prolonged. The mixture of hazardous pollutants formed by the reaction between UV rays and smog can travel on the wind to rural areas, meaning the photochemical smog does not just impact big cities.

The gas has been shown to affect the function of the lungs, irritating the membranes and lining of the smaller airways and air sacs in the lower respiratory tract. During exercise, changes in lung function, such as the maximum amount of air the lungs can move in and out, have been observed. These effects are potentially serious for people suffering from chronic bronchitis or allergies.

Children and asthmatics are especially prone. showing adverse effects. Changes in immune cells in lung tissue, similar to those caused by tobacco smoke, have recently been observed.

Photochemical smog also has devastating effects on the environment. The collection of chemicals found in photochemical smog causes problems for plants and animal life. Some plants such as tobacco, tomato and spinach are highly responsive to ozone, so photochemical smog can decimate these sensitive crops, trees and other vegetation. Ozone causes necrotic (dead) patterns on the upper surfaces of the leaves of trees. Ground-level ozone also can interfere with the growth and productivity of trees. The effects of smog on animals are also similar to its effect on humans; it decreases lung capacity and lung elasticity.

How do I safeguard myself from these risks? Is anything being done?

Take precautionary steps to keep safe against the ill effects of photochemical smog. Generally, photochemical smog is less concentrated in the early morning or evening; therefore, exercising and planning outdoor activities during this part of the day limits smog exposure. Emissions from cars and other vehicles are the largest sources of smog. Reduce your daily pollutant emissions by driving less, making use of carpools, and maintaining the car in good condition. Other small actions, such as tightly sealing the lids of chemical products like garden chemicals, solvents, and household cleaners, minimizes evaporation of the chemicals and helps reduce smog.

The problem of photochemical smog has also prompted some more serious reforms in an effort to reduce emissions. Switching over to other types of fuels, desulfurization of fuel gases from coal-fired power plants, expansion of public rail transport and low emission application of fertilizer in agriculture are some of the steps which have drastically reduced the level of photochemical smog.

Some measures have been taken around the world to reduce photochemical smog. Tight emissions regulations on vehicles and factories are one such step; many factories must use scrubbers and treatment systems before releasing air from their manufacturing facilities, for example. The use of harmful chemicals is also restricted in some regions of the world, since these chemicals can create photochemical smog. Government agencies also monitor air quality through testing, citing companies which violate the law and issuing warnings when smog levels are dangerous.