Carbon Monoxide and Smog

This section discusses carbon monoxide pollution and different types of smog, including their formation and effects.

Carbon monoxide (CO) is a dangerous pollutant produced when carbon-based materials are burned with insufficient oxygen, such as in the incomplete combustion of hydrocarbons in vehicle engines.

Definition: Carbon monoxide is a colorless, odorless gas that can be lethal in high concentrations due to its ability to interfere with oxygen transport in the body.

The effects of carbon monoxide on humans are severe:

• It binds to hemoglobin, preventing it from carrying oxygen from the lungs to body tissues.
• In high concentrations, it can cause brain damage and potentially death.

Control methods for carbon monoxide emissions include:

1. Exhaust catalytic converters: These devices oxidize CO to CO2.
2. Improved combustion efficiency: Ensuring complete combustion of fuels reduces CO production.

Highlight: While CO2 is also a pollutant, the increase in CO2 emissions from oxidizing CO is very small compared to other sources of CO2 emissions.

Smog is a type of air pollution that can take different forms:

1. Traditional smog: Forms on cloud-free nights when the ground cools rapidly, causing moist air above to condense into water droplets.

2. Photochemical smog: Results from the reaction of nitrogen oxides and hydrocarbons in the presence of sunlight, forming peroxyacetyl nitrates (PANs) and other pollutants.

Example: The infamous London "pea soup" fogs of the past were a form of traditional smog, while modern-day Los Angeles often experiences photochemical smog.

Factors contributing to photochemical smog include:

• Time: Rush hour traffic is a major source of NOx and hydrocarbons.
• Topography: Valleys are more susceptible due to decreased air flow.
• Meteorological conditions: Temperature inversions increase the likelihood of photochemical smog developing.

Acid Rain and Its Impacts

Acid rain is a significant environmental issue with far-reaching consequences. This section explores the causes and impacts of acid rain on both living and non-living entities.

Definition: Acid rain is precipitation that has become acidic due to atmospheric pollution, primarily from the combustion of fossil fuels and emission of photochemical smog.

The effects of acid rain on buildings and monuments are particularly severe. Limestone structures are especially vulnerable, as the acidic rain dissolves their surface layer. Metal structures such as railways, water pipes, and overhead power lines are also susceptible to damage from acid rain.

Example: The deterioration of historic buildings and monuments in cities with high pollution levels is a visible consequence of acid rain.

The acid rain effects on the environment extend to living organisms as well. Lichens, which are composite organisms formed from algae and fungi, are particularly sensitive to acidic conditions. Their size, health, and abundance can serve as indicators of sulphur dioxide levels in the environment.

Highlight: The impact of acid rain on soil pH and nutrient availability can lead to toxic levels of copper and zinc, further affecting plant and animal life.

The acid rain effects on humans are primarily indirect, through damage to the environment and food sources. However, direct effects can include:

1. Protein damage: Low pH can denature proteins in cell membranes and inhibit enzyme action.
2. Damage to exoskeletons: Invertebrates with calcium-based exoskeletons may die as acids dissolve these protective structures.
3. Respiratory issues: When combined with sulphur dioxide, acid rain can exacerbate breathing difficulties and increase the frequency of respiratory problems.

Vocabulary: Denaturation - The process by which proteins lose their structure, potentially leading to loss of function.