The Earth's Atmosphere
Gases that make up the atmosphere ( % by volume)
- Nitrogen (N2)- 78%
- Oxygen (O2)-21%
- Argon (Ar)- 1%
- Carbon Dioxide (CO2)- 0.04%
- Water (H2O)- 0-4% (variable)
The main air pollutants
- Sulfur Dioxide (SO2)
- Carbon Monoxide (CO)
- Nitrogen Dioxide (NO2)
- Particulates, carbon (C)
What are the main air pollutants?
Important air pollutants
- Sulfur Dioxide (SO2)- Causes acid rain
- Carbon Monoxide (CO)- A poisonous gas. Changes the amount of O2 in the blood and can kill
- Nitrogen Dioxide (NO2)- Causes acid rain and breathing problems, can make asthma worse
- Particulates, Carbon (C)- Makes things dirty, if breathed in can make asthma and lung infections worse
What can influence the air quality in different locations
- Emissions-Vehicles, power station and industry contribute to poor air quality
- Weather- pollutants are mixed and carried ( sometime miles) by the wind (e.g. Ozone , O3)
How are atmospheric pollutants formed?
Chemical changes that form atmospheric pollutants
- Many air pollutants are made through the burning of fossil fuels e.g. when O2 burns in C, CO2 is formed
- These changes involve atoms separating and joining
What happens during combustion reactions?
Chemical changes involved in combustion
- 1 O2 molecule splits and reacts with C. This forms CO2 gas
Ways of representing a chemical change
- As a chemical equation e.g. C+O2= CO2
- With pictures e.g. a pic. of the reactants and a pic. of the products
Where do all the atoms go?
Where do atoms go during chemical reactions?
- During chemical changes, all the atoms present at the beginning of a chemical reaction will be there at the end. Noatoms are made or destroyed- the atoms are conserved. They re-arrange to form new chemicals but they are still there.
Properties of reactants and products
- The properties of a chemical are what makes it different from other chemicals
- In any chemical reaction all the atoms you start with are still there at the end. But they are combined in a different way. So the properties of the products are different from the products of the reactants.
What happens to atmospheric pollutants?
- Particulate Carbon- Sticks to surfaces and makes them dirty, a primary pollutant
- Carbon Monoxide- A very poisonous gas, blocks oxygen being carried in the blood. Can oxidise into CO2, but takes a long time. A primary pollutant
- Nitrogen Monoxide-Comes from vehicle exhaust fumes. Quickly reacts with O2 to form NO2- happen within a few metres of the exhaust pipe.
- Sulfur Dioxide- Reacts with water vapour in the clouds to form acid rain.When it falls, the rain can damage plants and make lakes to acidic for fish
- Carbon Dioxide- Is used during photosynthesis. It is essential for plant growth and the start of our food chain. It can also dissolve in seas and oceans where it reacts with other chemicals. Human activity is increasing the amount of CO2 in the atmosphere, is contributing to global warming
- Nitrogen Dioxide- Makes acid rain ( see Sulfur Dioxide)
- Ozone- A secondary pollutant. Forms in the lower atmosphere when UV rays trigger chemical reactions between other pollutants- happens slowly. High level O3 shields us from UV but low level UV can weaken our immune system and damage our lungs
How does air quality affect our health?
Pollen and hay fever
- There is a correlation between pollen and hay fever- as the pollen count increase so does the number of cases of hay fever. But a correlation (link) doesn't always mean there is a cause. We know that pollen causes hay fever because skin tests show that people that suffer from hay fever are allergic to pollen.
Asthma and air quality
- Medical evidence shows that asthma attacks may be triggered by many different factors.
- There is no clear link between concentrations of air pollutants and people starting to get asthma.
- However, people who already have asthma have sensitive lungs, air pollutant may irritate them and make them sensitive to an attack
- Studies have shown that NO2 has an effect on asthma sufferers, there is a correlation but not a cause
How can new technology improve air quality?
How can government and individuals improve air qua
- In general, bigger cars and cars with bigger engines produce more air pollutants. Owners of these car could pay a higher vehicle excise tax (car tax)
- Higher fuel prices could discourage people from using their cars. It would also encourage people to buy fuel efficient cars. Both would reduce air pollutants
Energy Efficient Grants
- These grants mights include payments for fitting wall of roof insulation. They also might include the fitting of a high efficiency boiler, such as a condensing boiler