What problem is air pollution to cities?

Answer 1

The most common "city pollution" people think of is Photochemical Smog. I quote: "Photochemical smog is an atmospheric condition that produces severe eye irritation and poor visibility, to name just two of the effects. Three ingredients -- energy from a light source (ultraviolet), hydrocarbons, and nitrogen oxides -- are needed for photochemical smog to be formed. Two of those components are produced through the burning of fossil fuels, most notably automobiles. Photochemical smog is also sometimes known as "oxidizing smog", in that it has a high concentration of oxidizing agents. Ozone is a common oxidizing agent found in photochemical smog. Another type of smog, "reducing smog", has high concentrations of sulfur dioxide, which is a reducing agent. Its presence has historical significance in studies done in places like London, which used sulfur-containing coal as its main energy source."

Basically your car burns fuel in air/oxygen. We all know CO2 is one product of this combustion, but depending on the air to fuel (A/F) ratio, other compounds are also formed. The perfect stoichiometric point for gasoline is 14.7; or 14.7 pounds of air to 1 pound of gasoline. Any more air and it's a lean ratio, any less and it's a rich ratio.

If the combustion was perfect, you would get your hydrocarbon gasoline combustion converted into heat, energy, CO2, N2, and H2O. But the combustion never is perfect, so you also get:

• Carbon monoxide (CO) is a poisonous gas that is colorless and odorless.
• Hydrocarbons or volatile organic compounds (VOCs) are a major component of smog produced mostly from evaporated, unburned .fuel.
• Nitrogen oxides (NO and NO2, together called NOx) are a contributor to smog and acid rain, which also causes irritation to human mucus membranes.

NO2 is the main culprit of Photochemical Smog. It can also cause acid rain and other problems. NOx can react with atmospheric oxygen to produce tropospheric Ozone (very bad). Unlike the the ozone up in the stratosphere protecting us, ground level ozone is smog, and harmful.

Your car's catalytic converter is an amazing invention from the 1970s that helps reduce these emissions. The reduction catalyst is the first stage of the catalytic converter. It uses platinum and rhodium to help reduce the NOx emissions. When an NO or NO2 molecule contacts the catalyst, the catalyst rips the nitrogen atom out of the molecule and holds on to it, freeing the oxygen in the form of O2. The nitrogen atoms bond with other nitrogen atoms that are also stuck to the catalyst, forming N2. For example:

2NO => N2 + O2 or 2NO2 => N2 + 2O2

Answer 2

Air pollution is a significant problem for cities as it poses health risks to residents, damages the environment, and impacts overall quality of life. It can lead to respiratory issues, Allergies, and even long-term health conditions. Additionally, air pollution contributes to the degradation of ecosystems, harms biodiversity, and reduces visibility. It also negatively affects tourism, economy, and the well-being of urban dwellers.