Question

The brown, hazy fumes of photochemical smog are due to (a) nitrogen dioxide (b) PAN formation (c) aldehydes (d) \(\mathrm{SO}_{2}\).

Short answer

The brown, hazy fumes of photochemical smog are primarily due to (a) nitrogen dioxide.

Step-by-step solution

Understanding the Components of Photochemical Smog

Firstly, recognize that photochemical smog is a type of air pollution that results from the reaction of sunlight with pollutants such as nitrogen oxides (NOx) and volatile organic compounds (VOCs) in the atmosphere. The brown haze characteristic of this smog is primarily due to nitrogen dioxide (NO2), a byproduct of these reactions.

Identifying the Primary Cause of the Brown Haze

Know that Nitrogen dioxide (NO2) is a reddish-brown gas that at high concentrations, contributes to the visible brown haze of photochemical smog. This makes it the primary cause for the characteristic color of this type of smog.

Eliminating Other Options

While PAN (Peroxyacyl nitrates), aldehydes, and sulfur dioxide (SO2) contribute to the composition and health impacts of photochemical smog, they are not primarily responsible for its brown color. PAN and aldehydes are more related to the smog's irritant properties, and SO2 is typically associated with industrial smog, not the brown haze of photochemical smog.

Key concepts

Nitrogen Dioxide

When discussing the factors that contribute to air pollution, particularly the formation of photochemical smog, nitrogen dioxide (NO2) often stands out. This gas emerges from various sources, predominantly from the burning of fossil fuels by vehicles and power plants.

Nitrogen dioxide is a significant player in the creation of smog because it reacts with sunlight to produce a range of secondary pollutants. Among these are ozone (O3) and fine particulate matter, which are known to impair air quality and pose health risks.

Furthermore, the presence of NO2 is indicative of other harmful nitrogen oxides in the atmosphere, collectively termed NOx. Controlling emissions of NOx is crucial as it not only contributes to smog but also acid rain and nutrient pollution in water bodies. Educational efforts and regulatory measures, such as the promotion of cleaner transportation options and the installation of advanced emission controls in industrial settings, are vital to reducing its environmental and health impacts.

Air Pollution

Air pollution is a complex mix of particles and gases that can include substances like nitrogen oxides, sulfur dioxide, and volatile organic compounds (VOCs). These elements can be detrimental to human health, ecosystems, and the climate.

The harmful effects depend on the pollutant type, its concentration in the atmosphere, and the duration of exposure. Respiratory issues, cardiovascular problems, and aggravation of existing health conditions are among the health risks associated with poor air quality.

Short-term & Long-term Effects

Not only are there short-term health effects, like coughing and throat irritation but long-lasting impact on human health, including increased risks of heart disease and lung cancer.

The fight against air pollution involves implementing strict air quality standards, encouraging sustainable lifestyle choices, and investing in renewable energy sources to decrease reliance on fossil fuels. Educating the public about the sources and effects of air pollution is crucial in galvanizing community support for cleaner air initiatives.

Visible Brown Haze

The visible brown haze frequently seen blanketing cities, particularly during warm, sunny days, is a hallmark of photochemical smog. This characteristic hue is primarily attributed to the presence of nitrogen dioxide in the atmosphere. Upon reacting with sunlight, NO2 undergoes chemical changes that result in this colored smog.

The appearance of the brown haze is often a clear indicator of compromised air quality and is a signal for potential health risks for the urban population. It reduces visibility and is a frequent concern in urban environmental management.

Reducing Exposure

To minimize the impact, individuals can reduce exposure by staying indoors on days when the air quality index (AQI) is high, especially during peak sunlight hours when photochemical reactions are most intense.

Addressing this environmental challenge requires measures such as the advancement of public transportation, the adoption of clean energy technologies, and urban planning that reduces traffic congestion. Through these efforts, the frequency and severity of the brown haze can be diminished, leading to healthier cities and a better quality of life.