How is photochemical smog

Panoramic view of Santiago covered by a layer of smog on May 10, The Metropolitan Region of Santiago facing the driest autumn last 28 years due to lack of rainfall, which coupled with poor air circulation, causes an increase in smog.

Alternative Reactions NO and NO 2 can also react with the hydrocarbons instead of ozone to form other volatile compounds known as PAN peroxyacetyl nitrate. Santiago-Smog Flickr - Photo Sharing!. When sunlight hits these chemicals, they form airborne particles and ground-level ozone —or smog. Ozone can be helpful or harmful. But when ozone is close to the ground, it is bad for human health. Ozone can damage lung tissue , and it is especially dangerous to people with respiratory illness es like asthma.

Ozone can also cause itchy, burning eyes. Smog is unhealthy to humans and animals, and it can kill plants. Smog is also ugly. It makes the sky brown or gray. Smog is common in big cities with a lot of industry and traffic. Cities located in basin s surrounded by mountains may have smog problems because the smog is trapped in the valley and cannot be carried away by wind. Los Angeles, California, and Mexico City , Mexico, both have high smog levels partly because of this kind of landscape.

Many countries, including the United States, have created laws to reduce smog. Some laws include restriction s on what chemicals a factory can release into the atmosphere, or when the factory can release them. Some communities have "burn days" when residents can burn waste such as leaves in their yard. These limits on chemicals released into the air reduce the amount of smog. Smog is still a problem in many places.

Everyone can do their part to reduce smog by changing a few behaviors, such as:. Today, however, Mexico City is one of the smoggiest places on Earth. More than 4, people died from respiratory ailments as a result. The smog was so thick that the city had to shut down roads, railways, and the airport.

Robbers used the cover of smog to break into houses and shops. Ultraviolet is often shortened to UV. In the second set of equations, it is apparent that nitrogen oxide, produced in equation 1, is oxidized in equation 6 without the destruction of any ozone. This means that in the presence of VOCs, equation 3 is essentially eliminated, leading to a large and rapid build up in the photochemical smog in the lower atmosphere.

Figure 1, courtesy of the EPA, depicts concentrations and constituents of photochemical smog throughout the course of an average work day. In the morning, NO and VOC concentrations are high, as people fill their cars with gas and drive to work.

At midday, NO 2 concentrations peak just before solar radiation becomes intense enough to photolyze the NO 2 bond, releasing an oxygen atom that quickly gets converted into O 3. By late afternoon, peak concentrations of photochemical smog are present. Every new vehicle sold in the United States must include a catalytic converter to reduce photochemical emissions.

Catalytic converters force CO and incompletely combusted hydrocarbons to react with a metal catalyst, typically platinum, to produce CO 2 and H 2 O. Additionally, catalytic converters reduce nitrogen oxides from exhaust gases into O 2 and N 2 , eliminating the cycle of ozone formation.

Many scientists have suggested that pumping gas at night could reduce photochemical ozone formation by limiting the amount of exposure VOCs have with sunlight. London-type smog is mainly a product of burning large amounts of high sulfur coal. Clean air laws passed in have greatly reduced smog formation in the United Kingdom; however, in other parts of the world London-type smog is still very prevalent.

The main constituent of London-type smog is soot; however, these smogs also contain large quantities of fly ash, sulfur dioxide, sodium chloride and calcium sulfate particles. If concentrations are high enough, sulfur dioxide can react with atmospheric hydroxide to produce sulfuric acid, which will precipitate as acid rain. Because ozone is highly reactive, it has the ability to oxidize and destroy lung tissue.

Short term exposures to elevated levels of ozone above. Prolonged exposure to the molecule has been proven to cause a permanent reduction in lung function, as well as elevate the risk of developing asthma. Sulfur dioxide is a common component of London smog. Epidemiological studies have linked short term sulfur dioxide exposure to respiratory irritations including coughing, wheezing, and pharyngitis.

List three factors that make the Los Angeles Basin an ideal place for photochemical smog formation. These oxidizing compounds have been linked to a variety of negative health outcomes; ozone, for example, is known to irritate the lungs.

Smog can also affect areas of the country that are sunny less frequently, such as New York City. In fact, most major cities have problems with smog and air pollution. Boundless vets and curates high-quality, openly licensed content from around the Internet. This particular resource used the following sources:. Skip to main content. Chemistry and the Real World.