Acid rain and Heat Island effect
Air Pollution and Control
What is Acid Rain
• When the droplets of water of the rain, snow
or fog contain acidic component, it is called
acid rain. Normally the pure water has the pH
• pH 7 indicates the neutral, not acidic neither
basic. pH is measure of acidic and alkaline
nature of a solution.
• Naturally normal rain water has the pH value
5.6. When this value goes under 5.6 then it is
considered as acid rain.
What Causes Acid Rain
• Sulfur dioxide that is used in power
• Nitrogen oxide that is used in
• CO2 and Ozone those are produced
by burning of different types of
• CO released from vehicles.
• CFC gas that is used in
refrigerators and air conditioning
• Forest Fires.
Effects of Acid Rain
Acidify the water of lake, stream, river.
Destroys the forest.
Kills the living things in the water.
Causes health problems if affected
vegetables are Consumed by us.
• Destroys non-replicable buildings and
Steps than can reduce Acid
• Minimum use of electricity which
reduces load on power plants
• Desulphurization and denitrification of
• Lessening uses of air conditioners.
• Reducing the uses of the fossil fuel.
• The amount of use of motor vehicle
should be lessened.
• Try to use ethanol, propane or natural
gas rather than other fuels.
• Addition of lime to acidified water
Most affected Areas by Acid Rain
Northeastern area of united states
Southeastern area of Canada
• India and
Acid rain is a threat for us as well as
for the ecosystem of the nature. So,
each of us should be careful about it
and also try to lessen the factors that
• During night, cool air comes in contact with
heated vertical building surfaces and roads.
• Gets warmed and moves up. It carries all
the pollutional load of the city.
• As it moves up ,cools down and moves
• The cycle continues.
• Because of this temperature of city
increases during night hours as compared
to rural area
• This cycle is broken by strong winds.
What is Heat Island?
• As urban areas develop, changes occur in
their landscape. Buildings, roads, and other
infrastructure replace open land and
vegetation. Surfaces that were once
permeable and moist become impermeable
• These changes cause urban regions to
become warmer than their rural
surroundings, forming an "island" of
higher temperatures in the landscape.
• The term "heat island" describes built up areas that
are hotter than nearby rural areas. The annual
mean air temperature of a city with 1 million people
or more can be 1–3°C warmer than its surroundings.
In the evening, the difference can be as high as
• Heat islands can affect communities by increasing
summertime peak energy demand, air conditioning
costs, air pollution and greenhouse gas emissions,
heat-related illness and mortality, and water quality.
• Communities can take a number of common-sense
measures to reduce the effects of summertime heat
Effects1) Increased Energy Consumption
• Elevated summertime temperatures in cities increase
energy demand for cooling. Research shows that
electricity demand for cooling increases 1.5–2.0% for
every 0.6°C increase in air temperatures, starting from
20 to 25°C, suggesting that 5–10% of community-wide
demand for electricity is used to compensate for the
heat island effect.
• Urban heat islands increase overall electricity demand,
as well as peak demand, which generally occurs on hot
summer weekday afternoons when offices and homes
are running cooling systems, lights, and appliances.
2) Elevated Emissions of Air
Pollutants and Greenhouse Gases
• As described above, urban heat islands raise demand for
electrical energy in summer. Companies that supply
electricity typically rely on fossil fuel power plants to
meet much of this demand, which in turn leads to an
increase in air pollutant and greenhouse gas emissions.
• The primary pollutants from power plants include
sulfur dioxide (SO2), nitrogen oxides (NOx), particulate
matter (PM), carbon monoxide (CO), and mercury (Hg).
These pollutants are harmful to human health and also
contribute to complex air quality problems such as the
formation of ground-level ozone (smog), fine particulate
matter, and acid rain.
• Increased use of fossil-fuel-powered plants
also increases emissions of greenhouse
gases, such as carbon dioxide (CO2), which
contribute to global climate change.
• Elevated temperatures can directly increase
the rate of ground-level ozone formation.
Ground-level ozone is formed when NOx
and volatile organic compounds (VOCs)
react in the presence of sunlight and hot
3) Compromised Human Health and Comfort
• Increased daytime temperatures, reduced night-time
cooling, and higher air pollution levels associated with
urban heat islands can affect human health by
contributing to general discomfort, respiratory
difficulties, heat cramps and exhaustion, non-fatal heat
stroke, and heat-related mortality.
• Heat islands can also cause the impact of heat waves,
which are periods of abnormally hot, and often humid,
weather. Sensitive populations, such as children, older
adults, and those with existing health conditions, are at
particular risk from these events.
• Excessive heat events, or abrupt and dramatic
temperature increases, are particularly dangerous and
can result in above-average rates of mortality.
4) Impaired Water Quality
• High pavement and rooftop surface temperatures can
heat storm water runoff. Tests have shown that
pavements that are 38°C can elevate initial rainwater
temperature from roughly 21ºC to over 35ºC. This
heated storm water generally becomes runoff, which
drains into storm sewers and raises water
temperatures as it is released into streams, rivers,
ponds, and lakes.
• Water temperature affects all aspects of aquatic life,
especially the metabolism and reproduction of many
aquatic species. Rapid temperature changes in aquatic
ecosystems resulting from warm storm water runoff
can be particularly stressful, even fatal to aquatic life.
1. Increasing tree and vegetative cover;
2. Creating green roofs (also called
"rooftop gardens" or "eco-roofs");
3. Installing cool—mainly reflective—
4. Using cool pavements.
• Trees, vegetation, and green roofs can reduce
heating and cooling energy use and associated air
pollution and greenhouse gas emissions, remove
air pollutants, sequester and store carbon, help
lower the risk of heat-related illnesses and
deaths, improve storm water control and water
quality, reduce noise levels, create habitats,
improve aesthetic qualities, and increase
• Cool roofs can lower cooling energy use, peak
electricity demand, air pollution and greenhouse
gas emissions, heat-related incidents, and solid
waste generation due to less frequent re-roofing.
• Cool pavements can indirectly help reduce
energy consumption, air pollution, and
greenhouse gas emissions. Depending on the
technology used, cool pavements can improve
storm water management and water quality,
increase surface durability, enhance night-time
illumination, and reduce noise.
Q1. Acid rain has pH value less than _________.
Q2. _______________________ are island of
higher temperatures in the landscape.
Q3. Heat Island occurs in ________ areas.
Q4. Cool roofs reduces ____________ demand
Q5. Acid rain deteriorates common building
Prof S S Jahagirdar,NKOCET
Q1. What is ‘Acid rain’? Explain its causes,
effects and remedial measures.
Q2. Explain causes, effects and remedies of
‘Heat Island Effect’.
Prof S S Jahagirdar,NKOCET