what is sulfur dioxide so2


What is Sulfur Dioxide SO2?


Sulfur Dioxide is a gaseous form of air pollution, made from two components- sulfur and oxygen. This forms when sulfur-rich fuels burn such as oil, diesel, or coal. Sulfur dioxide already exists in the air composition but due to its various natural and man-made sources, the SO2 concentration can rise, resulting in severe effects on humans, plants, and the entire ecosystem.

Sources Of Sulfur Dioxide Gas

co from Volcanic eruption

–Volcanic eruption is one of the many natural causes of sulfur oxides. As molten lava rises to the surface, the pressure on the magma decreases, causing dissolved sulfur and other volatile components to combine to produce various new gases. Volcano eruptions emit sulfides that can travel upwards in the stratosphere and combines with water particles that cause acid rain.

co from Volcanic eruption

– Fossil fuels and especially the ones with a low filtration process have a high volume of sulfur in it which helps in the formation of many sulfur oxides. The burning of fossil fuels such as oil, coal, diesel, and other elements that contain sulfur emits sulfur dioxide into the atmosphere.

co from Volcanic eruption

– Among these combustion of fuels in plants and processes including extraction, refining of oil, etc are the major source of sulfur dioxide formation. Internal combustion engines, especially diesel engines are the major sources of sulfur dioxide production in urban areas. Indian government’s push for BSVI engines has made a significant impact on pollution as a whole.

SO2 in the Atmosphere


Sulfur Oxides are present in the atmosphere at low concentrations. Most of it is by human activities including the burning of fuel and essentially ship fuel as it has a high concentration of sulfur. In urban areas, a high concentration of sulfur oxides is detected. The life of sulfur dioxide in the atmosphere is less than a week during which it reacts with other atmospheric pollutants and forms various different compounds. When SO2 reacts with the oxygen present in the environment, it forms sulfur trioxide which dissolves with water vapor and forms sulfuric acid (H2SO4), a major acid rain component. It forms secondary pollutants like smog and particulate matter after attaching itself to dust particles which is quite harmful to the health and environment.


so2 in the atmosphere

Health & Environmental Impacts of SO2 Gas

Let’s find out the harmful effects of sulfur dioxide gas on our health.


Health Impact

If there is a high concentration of SO2, you can easily inhale SO2, which eventually sticks to the membrane of the nose and respiratory tract. Its short health impact can be felt quickly but the long-term impacts are very dangerous even to the extent of reduced lung capacity. It results in difficulty in breathing and tightening of airways. People with comorbidities are at high risk as it can aggravate those conditions to a point of no return.

eyes problem due to so2 gas

Eyes, nose,

Cough due to so2 gas


 throat problem due to so2 gas

Respiratory tract
inflammation &

 Risk of asthma attacks increases in children

Risk of asthma
attacks increases
in children

 Heart diseases


Environmental Impact


The impact of SO2 on the environment is beyond comprehensible. It limits plant growth and also damages leaves turning them yellow. At a high concentration in the atmosphere, it reacts with atmospheric moisture to create an acidic compound responsible for acid rain and damaging soil properties.

Monument damages due to so2 gas

It damages and stains
stones including culturally
important monuments
and statues.

plant tissues problems due to so2 gas

Impact plant growth
by damaging
exposed tissues in leaves

 Increased chances of acid rain

chances of
acid rain

Affects the vegetation, growth of plants

Affects the vegetation,
growth of plants

damage plan leaf due to so2

Deteriorates leaves
quality and color

damage marine life due to so2 gas

Affects marine life
by acidifying
the water ways

alter soil due to so2 gas

Alters soil properties,
agricultural land

Affects the vegetation, growth of plants

Destruction of parts
of lungs and inflammation
in the airways in animals

Sulfur Dioxide (SO2) and the harm it causes

SO2 Levels and their health effects

Levels (µg/m3)
Health Effects

0-40 (mg/m3)

Fresh air


Irritation in the eyes and respiratory tract experienced
Moderately polluted


Reflex bronchoconstriction with increased pulmonary resistance experienced


Brain and lung damages after exposure of 3 hours
Very poor


Exposures can cause Skin and respiratory tract burns


Life-threatening, Fatal within 60 minutes of exposure
*NAQI as per CBCB. 2-h hourly average values.

Corrective Measures To Reduce SO2 Gas

For the solutions to contain so2 concentration, first we need to monitor it and identify the areas where its concentration doesn’t meet the recommended standards. After identifying the target areas, some of the below mentioned corrective measures can be implemented:

use Sustainable energy

– Promote sustainable energy sources synergistic emission reduction includes the usage of water energy, wind energy, solar energy, etc. instead of fossil fuels to reduce SO2 emissions.

Alternative fuels

 – Alternative fuels like hydrogen cells, electrical, etc. This will help in reducing emissions from fossil fuel burning that emits SO2. Air pollution can be reduced substantially when we use alternative fuels.


build Home from industrial areas

– Accommodations away from industrial areas will help in reducing the effects of air pollution and harmful substances that can affect the residents, especially sensitive groups that live near industrial areas.

use Renewable sources

– Switch to a renewable source of energy such as solar, wind, and hydropower. Air pollution and economic growth go hand-in-hand. Using renewable sources of energy would be an economic approach to reducing emissions.

reduce using Sulfur fuel

– Using zero sulfur content fuels in cars and other vehicles will help in reducing ambient air pollution. Reducing sulfur fuels will help in reducing tailpipe HC, CO, and NOx emissions.


– Avoid exercising during high-pollution days as when you work out you inhale more O2 than normal along with other air pollutants. This means you inhale more air pollution when you work out during high-pollution days.

Coal plant

– Installation of power plants with scrubbers. The smokestack scrubber helps in collecting harmful chemicals and toxins and then releases clean air into the atmosphere through the smokestack.

Air quality sensor to measure SO2

air quality monitor to measure so2 level

Choose Your Air Quality Monitor To Measure SO2 Gas

prana air caaqms outdoor monitor