Topic: Air pollution and it’s effects on Plants health.

Air Pollution

Air pollution refers to the presence of harmful substances in the atmosphere that can affect
human health, the environment, and the climate. These pollutants can include gases (like carbon
monoxide and sulfur dioxide), particulate matter (tiny particles or droplets), and biological
molecules. Air pollutants could be classified into primary pollutant and secondary pollutant.

1. Primary Pollutants

Definition: These are pollutants that are directly emitted into the atmosphere from a source.
Sources: Common sources include vehicles, factories, power plants, agricultural activities, and
natural events like wildfires and volcanic eruptions.

Examples:

Carbon Monoxide (CO): Emitted from vehicle exhaust and industrial processes.

Sulfur Dioxide (SO₂): Produced by burning fossil fuels and industrial processes.

Nitrogen Oxides (NOx): Released during combustion processes, such as from cars and power
plants.

Particulate Matter (PM): Directly emitted from sources like construction sites, smokestacks, and
wildfires.

2. Secondary Pollutants

Definition: These are pollutants that form in the atmosphere through chemical reactions
involving primary pollutants and other atmospheric components.

Formation: Secondary pollutants are usually created when primary pollutants react with
sunlight, water vapor, or other atmospheric chemicals.

Examples:

Smog: A combination of various secondary pollutants, typically including ozone and particulate
matter.
 Acid Rain: Formed when sulfur dioxide (SO₂) and nitrogen oxides (NOx) react with water vapor
in the atmosphere to create sulfuric and nitric acids.

Air pollution is a significant public health issue and is responsible for millions of deaths
worldwide each year. According to recent estimates from the World Health Organization
(WHO), around 7 million people die annually due to air pollution. This includes both outdoor
(ambient) air pollution and indoor (household) air pollution. Outdoor air pollution is responsible
for an estimated 4.2 million deaths per year. Indoor air pollution is mainly due to household
pollutants, such as smoke from cooking with solid fuels, causing approximately 3.8 million
deaths annually. These deaths are primarily due to respiratory diseases, cardiovascular diseases,
stroke, and certain types of cancers linked to prolonged exposure to pollutants.

Sources:

Air pollution comes from various natural and human-made sources.

Here are some of the major sources:

1. Transportation

Cars, trucks, buses, and planes release pollutants like carbon monoxide, nitrogen oxides, and
particulate matter.

These vehicles burn fossil fuels, releasing toxic emissions that contribute significantly to air
pollution, especially in urban areas.

2. Industrial Processes

Factories, power plants, and refineries emit pollutants such as sulfur dioxide, nitrogen oxides,
and particulate matter.

These facilities often burn coal, oil, or gas to generate energy or process materials, which results
in pollution.

3. Agricultural Activities

Farming activities release ammonia from fertilizers, as well as methane and nitrous oxide from
livestock.

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 Pesticides, herbicides, and dust from tilling also contribute to air pollution.

4. Construction and Demolition

Dust, particulate matter, and other pollutants are released during construction activities.

Heavy machinery used in construction sites also emits pollutants.

5. Waste Management

Landfills and waste incineration produce pollutants such as methane, carbon dioxide, and other
harmful chemicals.

Open burning of waste also releases toxic chemicals into the air.

6. Household Sources

Burning of wood, coal, or other materials for cooking or heating can release carbon monoxide,
volatile organic compounds (VOCs), and particulate matter.

Household products like paints, cleaning supplies, and air fresheners can also release VOCs.

7. Natural Sources

Wildfires release large amounts of smoke, particulate matter, and other gases.

Volcanic eruptions emit sulfur dioxide, ash, and other pollutants.

Dust storms and pollen can also contribute to particulate pollution.

Addressing these pollution sources is essential for improving air quality and reducing health
impacts.

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 Types of Air Pollution

Smog and soot are two significant forms of air pollution that impact health, visibility, and the
environment.

1.Smog

Smog is a type of air pollution that forms when sunlight reacts with pollutants like nitrogen
oxides (NOx) and volatile organic compounds (VOCs).

Effects of Smog:

Irritates the eyes, throat, and lungs.

Aggravates respiratory conditions like asthma and bronchitis.

Reduces visibility and harms vegetation.

2.Soot (Particulate Matter)

Soot, also known as particulate matter (PM), consists of tiny solid and liquid particles suspended
in the air. It is a major component of air pollution and includes both PM2.5 (particles smaller
than 2.5 microns) and PM10 (particles smaller than 10 microns).

Sources of Soot:

Combustion of fossil fuels, such as coal, oil, and gas.

Vehicle emissions, especially diesel engines.

Effects of Soot:

Inhalation can cause respiratory and cardiovascular issues, especially PM2.5, which can
penetrate deep into the lungs.

Contributes to climate change by absorbing sunlight and affecting cloud formation.

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 Effect of Air Pollution on Plants.

Sulphur dioxide ( SO2 )

Sulphur dioxide (SO₂) is a colorless gas with a sharp, pungent odor. It is commonly associated
with the smell of burning sulfur.

Human effects: SO2 can cause respiratory issues, cardiovascular effects, Irritation of mucous
membranes and Potential impact on skin etc

Environmental effects: SO₂ can react with water vapor and other chemicals in the atmosphere
to form sulfuric acid, leading to acid rain. SO2 and acid rain can cause water bodies like lake
and streams become more acidic.

Impacts on Plants:

Sulfur dioxide (SO₂) can have several detrimental effects on plants, impacting their growth,
development, and overall health. Here are some of the main effects:

1. Leaf Damage

SO₂ can cause visible injury to leaves, such as chlorosis (yellowing), necrosis (browning or death
of tissue), and spotting. This reduces the plant’s ability to carry out photosynthesis effectively.

2. Reduced Photosynthesis

SO₂ interferes with the photosynthetic process by damaging chlorophyll, the pigment
responsible for capturing light. This reduces the plant’s ability to produce food, stunting growth
and reducing yield in crops.

3. Altered Growth and Development

Exposure to high levels of SO₂ can stunt plant growth by reducing the amount of nutrients
available for the plant’s development.

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 Sensitive plants may have reduced flowering and fruit production, affecting both natural
ecosystems and agricultural productivity.

4. Soil Acidification

When SO₂ is absorbed into the soil, it can acidify it, which may change the soil’s chemistry and
make it difficult for plants to absorb necessary nutrients, such as nitrogen, phosphorus, and
potassium.

Acidic soils can also leach essential minerals like calcium and magnesium, further impacting
plant health and growth.

5. Weakened Resistance to Disease and Pests

Plants weakened by SO₂ exposure are more susceptible to diseases and pest infestations.

Damage to leaves and reduced growth rates can make plants more vulnerable to fungal
infections, insect attacks, and other environmental stressors.

Marginal and intervenial necrosis Dark, reddish pigmentation on

American beech leaves exposed to Dogwood leaves exposed to

Sulfur dioxide. Sulfur dioxide.

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 Nitrogen dioxide:

Nitrogen dioxide (NO₂) is a reddish-brown gas with a sharp, pungent odor. It is a significant air
pollutant and part of a group of gases known as nitrogen oxides (NOx), primarily released
through combustion processes, such as:Vehicle Emissions, Power Plant, Industrial Processes.

Health and Environmental Impacts:

Health: Exposure to NO₂ can cause respiratory problems, asthma, and decrease lung function,
particularly affecting children, the elderly, and those with pre-existing conditions.

Environment: NO₂ contributes to the formation of ground-level ozone and fine particulate
matter, which can harm ecosystems. It also plays a role in the formation of acid rain, which can
damage soil, water bodies, and plant life.

Impacts on Plants

Nitrogen dioxide (NO₂) can have several adverse effects on plants, particularly when present in
high concentrations. Here are some key effects:

1. Inhibition of Photosynthesis

NO₂ can interfere with the photosynthetic process by damaging chlorophyll, the pigment
responsible for capturing light. This damage reduces the plant’s ability to produce food and
energy.

2. Leaf Damage and Necrosis

Prolonged exposure to NO₂ can cause visible injuries to plant leaves, including chlorosis
(yellowing), bronzing, and necrosis (cell death). Leaves may develop brown or black spots,
which can reduce the plant’s aesthetic appeal and vigor.

3. Stunted Growth

The toxic effects of NO₂ can impair various metabolic processes, leading to slower or stunted
growth. This can affect the overall size and health of the plant.

4. Reduced Yield and Quality

For crops, NO₂ exposure can lead to a reduction in yield and quality. This is particularly
detrimental to agricultural productivity, as affected plants may produce smaller fruits,
vegetables, or grains.

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 5. Altered Nutrient Absorption

NO₂ exposure can disrupt nutrient uptake in plants, leading to deficiencies in essential nutrients
like nitrogen, phosphorus, and potassium. This can further contribute to reduced growth and
vigor.

6. Impact on Seed Germination and Development

High levels of NO₂ can inhibit seed germination and adversely affect early plant development.
This is especially concerning for sensitive species and can have lasting effects on plant
populations in polluted areas.While plants can sometimes tolerate low levels of NO₂, prolonged
exposure or high concentrations can significantly harm their health and productivity.

Tomato plant exposed to NO2

Fluorides
Fluorides, particularly in the form of hydrogen fluoride (HF) and other gaseous compounds, are
common air pollutants resulting from various industrial processes. These compounds can be
released into the atmosphere through activities like aluminum production, phosphate fertilizer
manufacturing, glass making, and coal burning.

Effects on Health

Fluoride exposure in high concentrations can have adverse health effects, including:

Respiratory Issues, Skeletal Fluorosis, Dental Fluorosis..

Environmental Impact

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 Fluorides in the air can also have negative effects on the environment: Vegetation, Animal
Health, Soil and Water Contamination.

Impacts on Plants

Fluoride can have various effects on plants, depending on the concentration, the plant species,
and environmental conditions. Here are some of the main effects:

1. Toxicity

Leaf Damage: Excessive fluoride can cause necrosis (brown, dead tissue) at the leaf tips and
margins. This is commonly referred to as “tip burn” and can lead to extensive leaf damage.

Reduced Growth: High fluoride levels can inhibit plant growth by disrupting cellular processes,
reducing chlorophyll production, and impairing photosynthesis.

Delayed Germination: Fluoride can interfere with seed germination and initial seedling
development.

2. Photosynthesis Inhibition

Fluoride ions can disrupt the photosynthetic process by damaging chloroplasts and reducing
chlorophyll content. This decreases the plant’s ability to perform photosynthesis effectively,
reducing its energy production and overall vitality.

3. Nutrient Imbalance

High fluoride levels can interfere with the uptake and transport of essential nutrients such as
calcium, magnesium, and phosphorus. This imbalance can lead to deficiencies and further inhibit
growth.

4. Enzyme Inhibition

Fluoride can inhibit various enzymes that are critical for plant metabolism, including enzymes
involved in respiration and protein synthesis. This can lead to metabolic issues and stunt growth.

5. Accumulation in Edible Parts

In plants that are grown for food, fluoride can accumulate in edible parts (leaves, stems, roots).
This may lead to health concerns for animals and humans consuming the plants, as fluoride is
toxic in high amounts.

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 Yellowish -mottle and marginal Tip necrosis on needles of eastern

chlorosis on sweetgum leaf to fluorides . white pine exposed to fluorides

Carbon monoxide (CO)

Carbon monoxide (CO) is a colorless, odorless, and tasteless gas that is toxic to humans and animals
when inhaled. It is a significant component of air pollution. It is produced by the incomplete
combustion of carbon-containing fuels, such as gasoline, natural gas, oil, coal, and wood. Because
it cannot be seen, smelled, or tasted, CO is often referred to as the “silent killer.”

Health Impacts of CO Pollution

Short-term Exposure: Exposure to low levels of CO in the air can lead to symptoms like
headaches, dizziness, nausea, and confusion.

Long-term Exposure: Prolonged exposure to elevated CO levels can lead to serious health
problems, including impaired heart and brain function

Environmental Impacts

Air Quality: CO contributes to the formation of ground-level ozone, which is a harmful air
pollutant in itself.

Impacts on Plants

Carbon monoxide (CO) is generally harmful to plants and can affect them in various ways. The
main effects of carbon monoxide on plants are:

1. Reduced Photosynthesis:

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 Carbon monoxide can interfere with the plant’s ability to carry out photosynthesis by reducing
the amount of available carbon dioxide (CO₂) that plants need for this process.

CO can also bind with the iron in plant enzymes involved in photosynthesis, potentially reducing
their effectiveness.

2. Decreased Growth:

Exposure to CO can slow down plant growth by limiting energy production and nutrient uptake.

Long-term exposure may result in stunted growth and reduced development of roots, stems, and
leaves.

3. Impaired Respiration:

CO can disrupt cellular respiration in plants by interfering with oxygen availability. Plants, like
animals, need oxygen to break down sugars and produce energy.

When CO is absorbed by plant tissues, it can lead to oxidative stress, which damages cells and
impairs normal metabolic functions.

4. Increased Susceptibility to Stress:

Plants exposed to CO may become more vulnerable to other environmental stresses, such as
drought, heat, or pests.

This is because CO exposure can weaken plant defenses, making it harder for the plant to recover
from additional stressors.

5. Reduced Seed Germination:

High levels of CO can negatively affect seed germination rates, as the gas may prevent seeds
from absorbing the oxygen they need to begin sprouting.

This can lead to poor seedling development and reduced plant populations.

Ozone (O3 )
Ozone (O₃) is a molecule composed of three oxygen atoms, and it plays a complex role in air
pollution. While it’s essential in the stratosphere, where it forms the ozone layer that protects us
from the sun’s harmful ultraviolet (UV) radiation, ground-level (or tropospheric) ozone is a
significant component of smog and a harmful air pollutant.

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 Health Effects: Ozone at ground level can cause a range of health issues, Respiratory problems
(e.g., asthma, bronchitis), Reduced lung function, Irritation of the airways, Increased risk of
respiratory infections

Environmental Effects: Ground-level ozone can also harm vegetation and ecosystems. It can:

Damage crops, reducing agricultural yield.

Harm trees and other vegetation, affecting biodiversity.

Impacts on Plants:

1. Photosynthesis Reduction

Ozone enters the plant through the stomata (tiny openings on leaves) and can damage cells inside
the leaves.

It disrupts the photosynthesis process by damaging chloroplasts, which are essential for
producing energy from sunlight.

Reduced photosynthesis leads to lower energy production, which in turn limits the plant’s
growth.

2. Cellular and Tissue Damage

Ozone causes oxidative stress by forming reactive oxygen species (ROS) within the plant cells.

These ROS can damage cell membranes, proteins, and other cellular structures, leading to tissue
damage.

Leaves often develop visible symptoms like spots, chlorosis (yellowing), and necrosis (dead
tissue patches).

3. Reduced Growth and Yield

Due to damaged photosynthetic systems and cellular structures, plants experience stunted
growth and produce lower yields.

This is particularly problematic in agriculture, as crops exposed to high levels of ozone often
have reduced productivity.

4. Reduced Nutrient Content

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 Ozone stress can reduce the levels of essential nutrients in plants, affecting their nutritional
quality.

For example, ozone exposure can lower the protein content in crops like wheat, rice, and
soybeans, impacting food quality and human nutrition.

5. Premature Aging

Plants exposed to ozone tend to mature faster, often leading to premature aging.

This accelerated aging process can cause leaves to fall off earlier, reducing the plant’s ability to
produce energy over time.

6. Genetic and Epigenetic Changes

Prolonged exposure to ozone can cause changes in gene expression in plants.

These changes may affect the plant’s development, growth, and reproductive success over time.

7. Impact on Plant Reproduction

Ozone exposure can impair flowering, seed production, and overall reproductive success in
some plants.

This is critical for plants that rely on pollinators, as it can affect the timing and quality of floral
resources available to pollinators.

Browning on potato leaves shows Yellow -ring brown patches on

evidence exposure to high concentration. bean leaves shows exposure to

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 of ozone. Ozone.

Solutions of Air Pollution

Enhanced Air Quality Monitoring: Establish more monitoring stations to accurately track
pollution levels and make data available to the public.

Green Spaces: Increase green spaces like parks and urban forests, which can help absorb
pollutants and improve air quality.

Better Waste Management: Control and reduce waste burning, which is a major source of
toxic air pollutants.

Promote Eco-Friendly Habits: Encourage individuals to reduce energy consumption, carpool,

Composting and Recycling: Properly managing waste at home helps reduce the amount of
garbage sent to landfills and reduces pollution from burning or decomposition.

Support Clean Energy: If possible, switch to renewable energy providers or consider installing
solar panels for household energy.

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