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Inorganic gaseous pollutants. (IAQ). Introduction. Inorganic gaseous pollutants are the major contributors to Indoor quality problems Combustion appliances and tobacco smoke are the major sources of gases along with other types of pollutants These Inorganic gaseous pollutants include

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introduction
Introduction
  • Inorganic gaseous pollutants are the major contributors to Indoor quality problems
  • Combustion appliances and tobacco smoke are the major sources of gases along with other types of pollutants
  • These Inorganic gaseous pollutants include
  • Carbon monoxide.
  • Sulfur dioxide.
  • Nitrous oxide.
  • Nitrogen dioxide.
factors effecting concentration
Factors effecting concentration.
  • The emission patterns and concentrations of the pollutants depend on Following factors:
    • Types of Fuels used
    • Combustion efficiency
    • Appliance design
    • Ventilation system
    • Operating conditions
    • Maintenance
    • Frequency of use
appliances based on fuel type and their application
Appliances based on Fuel type and their application
  • Un-vented space heaters
  • Wood burning stoves
    • Furnaces
    • Fire places
behavior of combustion appliances
Behavior of combustion appliances
  • Un-vented space heaters
    • In this type of device the pollutant concentration is maximum within the first hour of furnace operation
    • The concentrations come to a standard steady state as the device is shut down
  • Wood burning appliances
    • These appliances emit pollutants intermittently and depend completely on the type of wood used
    • The other pollutants released due to the devices of this type include organic compounds (like HCHO)
    • The indoor to outdoor ratio of these Inorganic gaseous pollutants can be well over unity
health effects of co 2
Health Effects of CO2
  • The ratio of indoor to outdoor concentration of CO2 is generally greater than ‘1’
  • The concentration level of CO2 to cause any serious health problems in the range of 30,000 ppm
  • Respiration is effected at concentration levels from and above 15,000 ppm
  • Above 30,000 ppm it can cause headaches, dizziness and nausea
  • Prolonged exposure to concentration above 5000 ppm can increase the incidence of illness
  • The concentration of 5000 ppm is adopted as TLV for the submarines
health effects of co
Health Effects of CO
  • Health effects due to CO include loss of alertness, impaired perception, learning disorders, sleep deprivation, drowsiness and confusion
  • Health effects due to prolonged exposure to low concentration have been controversial, but acute illness and deaths have been reported
  • CO combines with hemoglobin and myoglobin to stop the supply of oxygen to tissues affecting brain, myocardium and muscle tissues
  • Carboxyhemoglobin can cause severe health effects at various percentage levels in blood
    • Loss of vigilance ability @ 3% - 5%
    • Loss of hand to eye co-ordination @6% - 10%
health effects of no and no 2
Health Effects of NO and NO2
  • At high level there can be very serious health effects like coma and eventual death
  • NO and NO2 are the most reactive species of the nitrogen oxides
  • They combine with other indoor pollutants to form complex toxic substances
  • React with amines like benzo(a)pyrene and pyrelene to form carcinogenic nitrosoamine and mutagens
health effects of so 2 and cl 2
Health Effects of SO2 and Cl2
  • SO2, another pollutant found indoor at 0.25 – 0.5 ppm can cause bronchioconstriction in exercising asthmatics
  • Short-term exposure to the low level of SO2 can cause irritation
  • Long term exposure can cause functional changes in lung making the body susceptible to damage by other pollutants
  • Cl2 gas another gas found when two cleaning agents are mixed together one containing acidic compound and another sodium hypochlorite
  • Cl2 gas can cause coughing, breathlessness, irritation of upper airways, bronco spasms, nauseas and vomiting
sources
Sources

Unvented space heaters

  • The unvented gas heater is one of the major sources of pollutants like Inorganic gaseous pollutants
  • This device can be classified into two categories
    • Gas space heaters – heaters of this type use gas as fuel
    • Kerosene space heaters - heaters that use kerosene as fuel
classification of kerosene space heaters
Classification of Kerosene space heaters
  • Convective
  • Radiant
  • Convective / Radiant
  • Two stage
  • Wickless
factors affecting emission rates
Factors affecting Emission rates
  • Emission rates of pollutants from kerosene space heaters depends on the following factors
    • Usage pattern
    • Type of heater
    • Type of fuel
    • Age of heater
significant emissions from kerosene space heaters
Significant emissions from Kerosene space heaters
  • All heaters emit NO, NO2, CO, CO2, respirable particles and formaldehyde
  • Emission rate of CO2 depends on type of fuel used and duration of burning
  • The average CO2 emissions rates are:
    • 49,8000 +/- 2400 mg/Kg from natural gas heaters
    • 60,500 +/- 1200 mg/Kg from a propane heater
    • 70,000 mg/Kg from a kerosene heater
  • CO, NO, NO2 and formaldehyde were emitted in various conditions in majority of the experiments
wood burning stove s fireplaces and furnaces as sources
Wood burning stove’s fireplaces and Furnaces as sources
  • These are potential sources for both indoor and outdoor air
  • They emit NO, NO2, CO, CO2, SO2, respirable suspended particles, benzo(a)pyrene and formaldehyde (which are vented outside)
  • Cracks and leaks in stovepipes, downdrafts, log roll over in fireplaces and negative air pressure cause the indoor pollution
  • The emissions of pollutants per cord of wood are generally:
    • 0.5 – 1.5 lb of sulphur
    • 0.7 – 2.6 lb of NOx
    • 300 – 1200 lb of CO
gas stoves and ovens
Gas stoves and Ovens
  • Gas stoves produce pollutants like CO, CO2, NO, NO2 and aldehyde indoors
  • CO level is increased by 20 – 25 ppm within the first 30 mins of operation, 1.2 ppm of NO in first 45 mins and 25 ppm of NO2
  • CO2 emissions for ovens in steady state were higher for a new stove compared to an old stove
  • The concentration of indoor pollutant is decided by
    • Air changes per hour
    • Number of heaters
    • Frequency of use
    • Airspace volume
other combustion sources
Other Combustion sources
  • Other sources of pollutants are water heaters, washers, dryers and attached garages
  • Several hobbies like welding and soldering etc are also sources of indoor air pollution
  • Tobacco smoke is the major contributor of respirable particles
  • Gas water heaters lead to high indoor concentration of Nitrogen oxides
measuring devices
Measuring Devices
  • Personal monitors are available only for CO, NO2 and SO2 and can work in all models
  • The most commonly used monitors are:
    • CODE – I
    • CODE – II
  • Portable / Stationary instruments are used to measure inorganic compounds concentration
  • Most common method used to measure CO and CO2 is nondispersive infrared (NDIR) photometry
other measuring devices
Other Measuring Devices
  • Individual concentration of gas in a gaseous mixture is measured by Thermal conductivity Detector (TCD)
  • Thermal conductivity Detector is used for quantifying CO, CO2 and H2O
  • Flame photometric method is used for SO2 and H2S
effective measuring methods
Effective Measuring Methods
  • The Gas filter Correlation method (GFC) is used to measure CO concentration (certified by EPA)
  • Ozone is measured by chemiluminescent method
  • SO2 concentration is measured by:
    • Colorimetric method
    • Flame photometric detection (FPD)
source control
Source control
  • The major contributors are the wood burning stoves, so removal of them indoors substantially reduces the pollution
  • Replacement of wood burning stoves by oil or gas fired furnaces
  • Modification in the design of the gas and kerosene stoves is another way to subside the indoor pollution
  • Other preventive measures like proper operation and regular maintenance of the burner could be a possible alternative
increased ventilation
Increased ventilation
  • Local and Mechanical ventilation are most effective in removing the pollutants
  • Hood installed over the cooking place is one of the most common local ventilation methods
  • Ductless Cooking ranges with Carbon filters are being used
  • Carbon filters have poor adsorption capacity (which can be improved by careful design)
  • Mechanical ventilation increases the air exchange rate hence decreasing the concentration of the pollutants
air cleaning
Air Cleaning
  • Absorption methods
    • This method can effectively remove the pollutants indoors
    • Liquid desiccant based air conditioning systems are being used indoors
    • Absorber using monoethanolamine is being used in submarines to reduce the concentration of CO2
    • The systems failed when the outdoor concentration was much higher
air cleaning1
Air Cleaning

Adsorption methods

  • Commonly used adsorbents are:
    • Silica gel
    • Activated alumina
    • Activated carbon
    • Manganese oxides
  • These adsorbents should be able to remove the moisture from indoor air using solid adsorbents (desiccants)