Photochemical smog is a mixture of pollutants that are formed when nitrogen oxides and volatile organic compounds (VOCs) react to sunlight, creating a brown haze above cities. It tends to occur more often in summer, because that is when we have the most sunlight.

Why is air pollution increasing in developing countries? They are using more fossil fuels.

What helps maintain global oxygen concentrations in the troposphere? Oxygen levels remain balanced by photosynthesis and cellular respiration.

Ground-level ozone constitutes one of the major components of photochemical smog, so called because of the photochemical reaction of air pollutants such as nitrogen oxides (NOx) and volatile organic compounds (VOCs) with ultraviolet light (sunlight); thus, the O3 levels vary strongly with season and the highest levels …

Health Effects It causes painful irritation of the respiratory system, reduced lung function and difficulty breathing; this is more evident while exercising or working outdoors. High levels of smog also trigger asthma attacks because the smog causes increased sensitivity to allergens, which are triggers for asthma.

What Does the Environmental Protection Agency Do? The Environmental Protection Agency (EPA) creates and enforces laws designed to protect the environment and human health. 4 As part of their mission, they seek to ensure that Americans have a clean environment, including the air, water, and land they use and enjoy.

1) It corrode metals, stones, rubber and painted surface. 2) It causes serious health problems to senior citizens, children and people with heart and lung problems which lead to emphysema, bronchitis, asthma.

Smog is a combination of smoke and fog which forms droplets that remain suspended in the air.

The word “smog” was coined in the early 20th century, and is a contraction (portmanteau) of the words smoke and fog to refer to smoky fog due to its opacity, and odor.

Types of air pollution

• particulate matter.
• nitrogen dioxide.
• ozone.
• sulphur dioxide.

The combination of smoke and fog is called smog. It is of two types: (b) Photochemical smog or Los Angeles smog: It is formed when the air contains NO2and hydrocarbons and the mixture is exposed to sunlight.

classical smog – This is the typical form of smog found in areas which have a humid climate. It is a mixture of smoke, fog and sulphur dioxide. This smog acts as a reducing agent in atmospheric pollution and hence it is also known as reducing smog.

Its components include smoke, fog and sulphur dioxide. It is reducing in nature. Photochemical smog occurs in a dry, sunny climate. Its components are PAN, acrolein, ozone, formaldehyde, nitric oxide. It is oxidizing in nature.

A fog of H2SO2 droplets formed condenses on the particulates to form the smog. It is of reducing nature. The gases released by automobiles and factories are not responsible for classical smog.

(a) Classical smog occurs in cool humid climate. It is a mixture of smoke, fog and sulphur dioxide. Chemically it is a reducing mixture and so it is also called as reducing smog.

Distinguish between classical smog and photochemical smog….

Classical smog is also called reducing smog as it acts as a reducing agent. The reducing character is due to presence of sulphur dioxide and carbon (soot) particles.

What is the prime indicator of the latter? Classic – Combination of smoke and fog.

Sulfurous smog, also known as London smog, develops due to high concentration of sulfur oxides in the air. Photochemical smog is produced when sunlight reacts with oxides of nitrogen and at least one volatile organic compound (VOC) in the atmosphere.

physician Harold Des Veaux

As the reaction take place in the presence of light to form the smog, it is called photochemical smog….Classical Smog vs Photochemical Smog.

Everyone can do their part to reduce smog by changing a few behaviors, such as:

1. Drive less.
2. Take care of cars.
3. Fuel up during the cooler hours of the day—night or early morning.
4. Avoid products that release high levels of VOCs.
5. Avoid gas-powered yard equipment, like lawn mowers.

local topography – low lying areas. climate – high air pressure areas. population density – number of vehicles. fossil fuel use.

Typically, air near the ground is relatively warm, and the atmosphere grows colder with elevation. During a temperature inversion, cold air is trapped beneath warm air, creating a pocket of stagnated air close to the Earth’s surface. Thermal inversions are more common than you may think.