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Air pollution & human health (Monitoring (Air Quality Indices= a unit…
Air pollution & human health
Air pollution
Impacts: can affect human health, visibility, crop growth, building erosion- impacts cultural heritage
The presence, or introduction into the air of a substance that has harmful or poisonous effects
N2=78%, O2=21%, Argon=0.9%, CO2= 400ppm
Average person breathes between 5-10 x/min, > 10,000 breaths/ day
O3, CO, SO2, NO2 are harmful substances
Main pollutants
Nitrogen dioxide (NO2)
Reddish brown gas, unpleasant smell and poisonous in high concs
naturally produced by bacterial and volcanic activity an lightning more than anthropogenically (power generation and transport)
Road transport estimated to be responsible for around 50% of total emissions of NO-
NO2 levels highest in cities
**
Sulfur dioxide (SO2)
Colourless gas with burnt match smell
Emitted naturally from volcanoes, anthropogenically from combustion of fuels (coal and oil fired power stations)
Forms acid rain
Ozone (O3)
Colourless gas- major component of atmospheric smog
Can come from stratosphere into troposphere naturally
Anthropogenically formed by chemical reactions between NOx (oxides) and NOCs in presence of sunlight
High concs found in rural areas, away from source of precursors
Particulate matter (PM2.5 & PM10)
Particulate matter=
tiny pieces of solid matter or liquids
Can consist of hundreds of different chemicals
Natural sources: sea salt, pollen, volcanoes etc and can be formed in atm
size is critical
Particles < 10um can pass into the lungs
Particles < 2.5um can pass into the bloodstream (diameter smaller than 2.5 micrometres)
- main cause of premature mortality due to air pollution
Pollutants
Primary pollutants=
directly emitted into the atmosphere (CO, CO2,SO2,NO, NO2)
Secondary pollutants=
formed within the atmosphere (HNO2, SO2, HNO3, H2SO2, H2O2)
WHO: "Ambient air pollution estimated to cause 3.7 million premature deaths worldwide in 2012"
The average UK life expectancy in UK is reduced by an average of 8 months due to air pollution
History of air pollution (UK)
Industrial revolution (1760-1820
)- increase in air pollution and smog events- cold winters, little mixing of air so pollutants collect close to ground-> smog
1952 London smog (mix of smoke and fog)- smoke concs increased to 56x normal levels- over 4000 people died
First accounts in 13th century-
poor air quality indoors, localised area close to source
Development of air quality legislation
National Air Quality Objectives for:
SO2
Aerosol particles/ PM10 and PM2.5
NO2/ NO
O3
Current trends
Overall decrease in air pollution in West Yorkshire since Clean Air Act
Large increase in air pollution in Beijing
Clean Air Act of 1956
Introduce smoke control areas
Control chimney heights
Move industry out from inner city
Established the "National Survey" which monitored black smoke and SO2- first UK air quality monitoring network
Health effects
Acute (short term)
Occurs during pollution episodes- people can require medical treatment
Aggravates pre-existing health conditions
General reduction in wellbeing
Effects can be reversible
Easier to link health effect to pollution event
Chronic (long term)
Can happen at low pollution levels
People often not aware of it
Shortened life span
Hard to attribute to a single cause
E.G: cancer, heart disease, decreased lung function
Air pollution and Alzheimers
Abundant quantities of minute magnetic particles associatesd with development of dementia and Alzheimers-
Particles sherical rather than angular- formed in a high temp process
Potential link- not yet conclusive
Monitoring
Exceedence=
period of time where conc is higher than that set out in standard
Objective=
target date on which exceedences of standard must not exceed specified number
EU limit values are legally binding EU parameters that must not be exceeded
Check standards and targets are met, inform public, identify long term trends, assess effectiveness of policies to control pollution
300 sites in UK that monitor air quality
Air Quality Indices=
a unit-less number used by many governments to communicate the level of air pollutions to general audience- simple way
As index increases, a larger fraction of population likely to suffer from adverse health effects
Daily Air Quality Index (DAQI):
combines average emissions, secondary pollutants, removal of species through wet deposition and dispersion of pollutants due to large scale meteorology