Inorganic gaseous pollutants

1. Inorganic gaseous pollutants (IAQ)

2. 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.

3. 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

4. Appliances based on Fuel type and their application • Un-vented space heaters • Wood burning stoves • Furnaces • Fire places

5. 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

6. Average NO2 , NO, and CO Concentrations in a house

7. Health Effects and standards

8. 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

9. 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%

10. 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

11. 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

12. Sources and Indoor Concentrations

13. 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

14. Classification of Kerosene space heaters • Convective • Radiant • Convective / Radiant • Two stage • Wickless

15. 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

16. 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

17. Emission Rates from Vented and Unvented Gas-fired Room Heaters

18. 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

19. 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

20. Emissions from Gas Stoves

21. 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

22. Sampling and Measurement

23. 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

24. 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

25. 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)

26. Reagents for Colorimetric Determination of Selected Inorganic Gases

27. Control Strategies

28. 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

29. 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

30. 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

31. 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)