Envi Chapter 6
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University of San Carlos - Department of Chemical Engineering
University of San Carlos - Department of Chemical Engineering
Air Pollution
The presence in the outdoor atmosphere of one or more air contaminants (i.e., dust, fumes, gas, mist, odor, smoke, or vapor) in sufficient quantities, of such characteristics, and of such duration as to be or to threaten to be injurious to human, plant, or animal life or to property, or which reasonably interferes with the comfortable enjoyment of life or property.
University of San Carlos - Department of Chemical Engineering
Historical Overview 61 A.D.: the Philosopher Seneca describe “the heavy air of Rome” and “the stink of the smoky chimneys thereof” 1273: King Edward I was bothered enough by the smoke and fog mixture that brooded over London to prohibit the burning of “sea coal”. Queen Elizabeth I passed law prohibiting the burning of coal when the Parliament was sitting. 1661: compliance to the law was still not obtained based from John Evelyn’s pamphlet, Fumifugium: or the Inconvenience of the Aer and Smoake of London Dissipated, together with some Remedies Humbly Proposed.
University of San Carlos - Department of Chemical Engineering
1930: an inversion trapped smog in Belgium’s highly industrialized Meuse Valley. 1952: the London smog disaster made it impossible to ignore ay longer the serious consequences of air pollution.
1955: the Air Pollution Control Act was introduced in the United States.
University of San Carlos - Department of Chemical Engineering
Air Quality Standards • Those for ambient air quality • Those for industrial emission
The key references for both ambient and emission standards are: • WHO (1987) – Air Quality Guidelines for Europe • TA Luft (1987) – Technical Instructions on Quality Control, Germany • EC (European Community) Directives(1987) • USEPA (1990) – National Air Quality Standards
University of San Carlos - Department of Chemical Engineering
Air Pollution System
Detector Response
Atmosphere Emission Source
Source Control Receptor
Humans, animals, flora, materials
Response
Figure 1. Air Pollution System (adapted from Seinfeld, 1986).
University of San Carlos - Department of Chemical Engineering
Table 1. Major Air pollutants and their sources. Pollutant
Sources of Activity Power Statio n
Traffic
Domesti c heating
Particulates
√
√
√
CO
√
√
√
√
CO2
√
√
√
√
SOx
√
√
√
√
√
NOx
√
√
√
√
√
VOCs
√
√
√
√
√
√
√
O3 HC
√
√
√
Zn Radionuclide s CFCs
Chemical, Pharmaceut ical
√
Manufacturin g metals, etc.
Waste Incinerati on
Agricultur e
√
√
√
√
√
√ √
Cu Cd
Quarrying, mining
√
Heavy Metals Pb Hg
Oil refinin g
√
√
√ √
√ √
√
√
√
√
√
√
√
√
√
√
√
√ √
√
√
√
University of San Carlos - Department of Chemical Engineering
Air Pollutants Primary Pollutants – those emitted by an identifiable source SO2, CO, NOx, SOx, particulates, hydrocarbons, and metals
Secondary Pollutants – those formed in the atmosphere by chemical reaction O3, other photochemical oxidants (peroxyacetyl nitrate) and oxidized hydrocarbons
Criteria Pollutants – those defined by the USA, EC and WHO CO, NO2, O3, SO3, PM- 10 (particulate matter of diameter < 10μm and lead
University of San Carlos - Department of Chemical Engineering
Table 2. Properties and pollution significant of criteria pollutants. Pollutant
Properties
Pollution Significance
Carbon Monoxide
Colorless, odorless gas
Formed during incomplete combustion of hydrocarbons. Causes greenhouse effects ad climatic change.
Nitrogen dioxide
Brown-orange gas
Significant component of photochemical smog and acid deposition.
Ozone
Highly reactive
A secondary pollutant, produced during formation of photochemical smog. Damages flora and materials.
Sulfur dioxide
Colorless, choking gas, soluble in H2O to produce sulfurous acid, H2SO3
Principal component of acid deposition. Damages humans, flora, fauna and materials.
Particulate matter < 10 μm in diameter
Coal burning power station, traffic, domestic coals, quarrying, and incineration. Can cause respiratory problems
Heavy metal, bioaccumulative
Principal source leaded petrol. Also from lead pipes, quarrying, incineration. Damages humans and fauna when in excess.
PM - 10
Lead
University of San Carlos - Department of Chemical Engineering
Units of Concentration Different ways of expressing concentrations of air pollutants · ppm (v/v) · ppb (v/v) · mg/m3 ·mg/Nm3 (Nm3 = normal dry m3 at STP)
At STP (00C and 101.3 kPa), 1 mole of an ideal gas occupies 22.4L At NSTP (non standard),
1 mole = 22.4
T 101.3kPa 273K P
University of San Carlos - Department of Chemical Engineering
Criteria Pollutants Carbon Monoxide, CO - most abundant of the criteria pollutants - a product of incomplete combustion of carbonaceous fuel - about 70% of all CO comes from mobile sources - can replace oxygen in the bloodstream and forming carboxyhemoglobin (COHb)
Nitrogen Oxides, NOx The oxides of gaseous nitrogen include: - NO - nitric oxide - NO2 - nitrogen dioxide - NO3 - nitrogen trioxide - N2O - nitrous oxide - N2O5 - nitrogen pentoxide
The acids of nitrogen include: - HNO2 - nitrous acid - HNO3 - nitric acid
University of San Carlos - Department of Chemical Engineering
Nitrogen Oxides, NOx - produced during the combustion of fossil fuels Fuel NOx - produced in the oxidation of nitrogen containing compounds in the fuel Thermal NOx - produced in the oxidation of atmospheric molecular N2 at high temperatures of combustion in the presence of oxygen
Oxidation of NOx
2 NO +O2 ⇔2 NO2 NO +O3 →NO2 +O2
Respiratory problems Smog
2 NO2 + H 2O → HNO3 + HNO2 3 NO2 + H 2O → 2 HNO2 + NO + O2 Reaction with organic compounds or hydrocarbons
HC + NOx + sunlight → photochemical smog
University of San Carlos - Department of Chemical Engineering
Sulfur Oxides, SOx - the product of fossil fuel combustion - dominant gaseous emission of sulfur is as sulfur dioxide with a small amount of sulfur trioxide
Sulfuric acid formation from SO2
SO2 +OH − →HOSO2 HOSO2
−
−
−
+O2 →SO3 +HO2−
SO3− +H 2O →H 2 SO4
−
Negative Impact of SO2 levels. 25 mg/m3 for 10 min exposures - can impaired bronchial functioning 50 μg/m3 - forest growth is inhibited
University of San Carlos - Department of Chemical Engineering
Particulate Matter - PM - 10 - emitted in the urban areas from power plants, industrial processes, vehicular traffic, domestic coal burning and industrial incineration
Table 3. Particulate Matter Size Group Description Composition Coarse
Dust, earth, crust matter
Fine
Aerosols, combustion particles, recondensed organic and metal vapors (primary and secondary pollutants)
Particle Size WHO USEPA (PM – 10) > 2.5 μm = 10 μm < 2.5 μm
= 10 μm
University of San Carlos - Department of Chemical Engineering
Table 4. Typical values of black smoke and PM concentration Location Rural Urban Maxima
Annual Concentrations Black Smoke (μg/m3) Suspended particles by gravimetry (μg/m3) 0 –10 0 – 50 10 – 40 50 – 150 100 – 150 200 – 400
Volatile Organic Compounds, VOCs - comprise hydrocarbons and other substances - methane is the most abundant - less abundant but more reactive VOCs include: ethylene oxide, formaldehyde, phenol, benzene, carbon tetrachloride and CFCs
University of San Carlos - Department of Chemical Engineering
Hydrocarbons, HC - one species of VOC emission - petroleum products - major sources include traffic, organic chemical production, transport and processing of crude oil and distribution of natural gas
Ozone, O3 - most abundant oxidant The irradiation of air containing hydrocarbons and oxides of nitrogen leads to: - Oxidation of NO to NO2 - Oxidation of HCs - Formation of O3
Lead, Pb - bluish-gray soft metal - bioaccumulative
University of San Carlos - Department of Chemical Engineering
Air Pollution
The presence in the outdoor atmosphere of one or more air contaminants (i.e., dust, fumes, gas, mist, odor, smoke, or vapor) in sufficient quantities, of such characteristics, and of such duration as to be or to threaten to be injurious to human, plant, or animal life or to property, or which reasonably interferes with the comfortable enjoyment of life or property.
University of San Carlos - Department of Chemical Engineering
Historical Overview 61 A.D.: the Philosopher Seneca describe “the heavy air of Rome” and “the stink of the smoky chimneys thereof” 1273: King Edward I was bothered enough by the smoke and fog mixture that brooded over London to prohibit the burning of “sea coal”. Queen Elizabeth I passed law prohibiting the burning of coal when the Parliament was sitting. 1661: compliance to the law was still not obtained based from John Evelyn’s pamphlet, Fumifugium: or the Inconvenience of the Aer and Smoake of London Dissipated, together with some Remedies Humbly Proposed.
University of San Carlos - Department of Chemical Engineering
1930: an inversion trapped smog in Belgium’s highly industrialized Meuse Valley. 1952: the London smog disaster made it impossible to ignore ay longer the serious consequences of air pollution.
1955: the Air Pollution Control Act was introduced in the United States.
University of San Carlos - Department of Chemical Engineering
Air Quality Standards • Those for ambient air quality • Those for industrial emission
The key references for both ambient and emission standards are: • WHO (1987) – Air Quality Guidelines for Europe • TA Luft (1987) – Technical Instructions on Quality Control, Germany • EC (European Community) Directives(1987) • USEPA (1990) – National Air Quality Standards
University of San Carlos - Department of Chemical Engineering
Air Pollution System
Detector Response
Atmosphere Emission Source
Source Control Receptor
Humans, animals, flora, materials
Response
Figure 1. Air Pollution System (adapted from Seinfeld, 1986).
University of San Carlos - Department of Chemical Engineering
Table 1. Major Air pollutants and their sources. Pollutant
Sources of Activity Power Statio n
Traffic
Domesti c heating
Particulates
√
√
√
CO
√
√
√
√
CO2
√
√
√
√
SOx
√
√
√
√
√
NOx
√
√
√
√
√
VOCs
√
√
√
√
√
√
√
O3 HC
√
√
√
Zn Radionuclide s CFCs
Chemical, Pharmaceut ical
√
Manufacturin g metals, etc.
Waste Incinerati on
Agricultur e
√
√
√
√
√
√ √
Cu Cd
Quarrying, mining
√
Heavy Metals Pb Hg
Oil refinin g
√
√
√ √
√ √
√
√
√
√
√
√
√
√
√
√
√
√ √
√
√
√
University of San Carlos - Department of Chemical Engineering
Air Pollutants Primary Pollutants – those emitted by an identifiable source SO2, CO, NOx, SOx, particulates, hydrocarbons, and metals
Secondary Pollutants – those formed in the atmosphere by chemical reaction O3, other photochemical oxidants (peroxyacetyl nitrate) and oxidized hydrocarbons
Criteria Pollutants – those defined by the USA, EC and WHO CO, NO2, O3, SO3, PM- 10 (particulate matter of diameter < 10μm and lead
University of San Carlos - Department of Chemical Engineering
Table 2. Properties and pollution significant of criteria pollutants. Pollutant
Properties
Pollution Significance
Carbon Monoxide
Colorless, odorless gas
Formed during incomplete combustion of hydrocarbons. Causes greenhouse effects ad climatic change.
Nitrogen dioxide
Brown-orange gas
Significant component of photochemical smog and acid deposition.
Ozone
Highly reactive
A secondary pollutant, produced during formation of photochemical smog. Damages flora and materials.
Sulfur dioxide
Colorless, choking gas, soluble in H2O to produce sulfurous acid, H2SO3
Principal component of acid deposition. Damages humans, flora, fauna and materials.
Particulate matter < 10 μm in diameter
Coal burning power station, traffic, domestic coals, quarrying, and incineration. Can cause respiratory problems
Heavy metal, bioaccumulative
Principal source leaded petrol. Also from lead pipes, quarrying, incineration. Damages humans and fauna when in excess.
PM - 10
Lead
University of San Carlos - Department of Chemical Engineering
Units of Concentration Different ways of expressing concentrations of air pollutants · ppm (v/v) · ppb (v/v) · mg/m3 ·mg/Nm3 (Nm3 = normal dry m3 at STP)
At STP (00C and 101.3 kPa), 1 mole of an ideal gas occupies 22.4L At NSTP (non standard),
1 mole = 22.4
T 101.3kPa 273K P
University of San Carlos - Department of Chemical Engineering
Criteria Pollutants Carbon Monoxide, CO - most abundant of the criteria pollutants - a product of incomplete combustion of carbonaceous fuel - about 70% of all CO comes from mobile sources - can replace oxygen in the bloodstream and forming carboxyhemoglobin (COHb)
Nitrogen Oxides, NOx The oxides of gaseous nitrogen include: - NO - nitric oxide - NO2 - nitrogen dioxide - NO3 - nitrogen trioxide - N2O - nitrous oxide - N2O5 - nitrogen pentoxide
The acids of nitrogen include: - HNO2 - nitrous acid - HNO3 - nitric acid
University of San Carlos - Department of Chemical Engineering
Nitrogen Oxides, NOx - produced during the combustion of fossil fuels Fuel NOx - produced in the oxidation of nitrogen containing compounds in the fuel Thermal NOx - produced in the oxidation of atmospheric molecular N2 at high temperatures of combustion in the presence of oxygen
Oxidation of NOx
2 NO +O2 ⇔2 NO2 NO +O3 →NO2 +O2
Respiratory problems Smog
2 NO2 + H 2O → HNO3 + HNO2 3 NO2 + H 2O → 2 HNO2 + NO + O2 Reaction with organic compounds or hydrocarbons
HC + NOx + sunlight → photochemical smog
University of San Carlos - Department of Chemical Engineering
Sulfur Oxides, SOx - the product of fossil fuel combustion - dominant gaseous emission of sulfur is as sulfur dioxide with a small amount of sulfur trioxide
Sulfuric acid formation from SO2
SO2 +OH − →HOSO2 HOSO2
−
−
−
+O2 →SO3 +HO2−
SO3− +H 2O →H 2 SO4
−
Negative Impact of SO2 levels. 25 mg/m3 for 10 min exposures - can impaired bronchial functioning 50 μg/m3 - forest growth is inhibited
University of San Carlos - Department of Chemical Engineering
Particulate Matter - PM - 10 - emitted in the urban areas from power plants, industrial processes, vehicular traffic, domestic coal burning and industrial incineration
Table 3. Particulate Matter Size Group Description Composition Coarse
Dust, earth, crust matter
Fine
Aerosols, combustion particles, recondensed organic and metal vapors (primary and secondary pollutants)
Particle Size WHO USEPA (PM – 10) > 2.5 μm = 10 μm < 2.5 μm
= 10 μm
University of San Carlos - Department of Chemical Engineering
Table 4. Typical values of black smoke and PM concentration Location Rural Urban Maxima
Annual Concentrations Black Smoke (μg/m3) Suspended particles by gravimetry (μg/m3) 0 –10 0 – 50 10 – 40 50 – 150 100 – 150 200 – 400
Volatile Organic Compounds, VOCs - comprise hydrocarbons and other substances - methane is the most abundant - less abundant but more reactive VOCs include: ethylene oxide, formaldehyde, phenol, benzene, carbon tetrachloride and CFCs
University of San Carlos - Department of Chemical Engineering
Hydrocarbons, HC - one species of VOC emission - petroleum products - major sources include traffic, organic chemical production, transport and processing of crude oil and distribution of natural gas
Ozone, O3 - most abundant oxidant The irradiation of air containing hydrocarbons and oxides of nitrogen leads to: - Oxidation of NO to NO2 - Oxidation of HCs - Formation of O3
Lead, Pb - bluish-gray soft metal - bioaccumulative
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