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Understanding Aerosols: Types, Sources, Measurement, and Their Impact on Air Quality**

Aerosols are tiny particles suspended in the air, classified into types such as liquid, solid, dust, and smoke. Key sources include natural phenomena like dust and pollen, as well as human activities like combustion. Their sizes vary, influencing their behavior in the atmosphere. Measurement techniques include Total Suspended Particulate (TSP) and PM10 analysis, using filters and absorbance methods. Aerosols significantly impact air quality and health, evidenced by studies in polluted urban areas. Understanding their nature and measurement is crucial for environmental monitoring.

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Understanding Aerosols: Types, Sources, Measurement, and Their Impact on Air Quality**

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  1. AEROSOLS: types • LIQUIID • SOLID • Dust • Smoke • Fly ash • pollen • Cloud • Mist • Fog • smog

  2. Mount manitoba, June 1991

  3. Asian brown cloud over China

  4. AEROSOLS: sources DUST SEA • Dust • Smoke • Fly ash • pollen • plant fragments • cement • brake lining • tires • soil chemical concentration factor (surface effects) CCF = [aerosol]/[sea]

  5. AEROSOLS: sizes • > 400 nm scatter light • < 0.01 micron coagulate • > 10 micron settle out • Typical size: 0.1-1 micron

  6. AEROSOLS: how to measure them • Alphabet soup: • COH • TSP • IP • TDF • PM10 • light scattering • collecting on filters

  7. AEROSOLS: how to measure them • Alphabet soup: • COH • TSP • IP • TDF • PM10 Coefficient of Haze Draw 300 meters through a filter measure absorbance x 100 >6 bad for asthma typical samples 5-10 micron

  8. AEROSOLS: how to measure them • Alphabet soup: • COH • TSP • IP • TDF • PM10 Total Suspended Particulate Weighing after filtering Units: μg/m3 “normal” ~ 10 μg/m3 sometimes 500 μg/m3 in cities

  9. AEROSOLS: how to measure them • Alphabet soup: • COH • TSP • IP • TDF • PM10 Inhalable Particulates Generally IP ~ 0.45 TSP

  10. AEROSOLS: how to measure them • Alphabet soup: • COH • TSP • IP • TDF • PM10 Total Dust Fall units: g m-2 month-1 should be < 7 g m-2 month-1 often exceeded in industrial areas

  11. AEROSOLS: how to measure them • Alphabet soup: • COH • TSP • IP • TDF • PM10 Particulate matter < 10 micron PM10 = TSP < 10 μ

  12. 50% (by mass) of a set of particles are less then 10 micron and 50% are between 10 and 20 micron. PM10 is what percentage of PM20? [A] 0.1 % [B] 10 % [C] 16 % [D] 50 % [E] 95 %

  13. 50% (by mass) of a set of particles are 10 micron and 50% are 20 micron. All particles larger than 10 micron are filtered out. How much does the total number of particles go down? [A] by 50% [B] by less than 50% [C] by more than 50% [D] It depends on the type of particle

  14. 10% (by mass) of a set of particles are 10 micron and 50% are 20 micron. All particles larger than 10 micron are filtered out. How much does the total surface area go down? [A] by 50% [B] by less than 50% [C] by more than 50% [D] It depends on the type of particle

  15. Wet deposition dry deposition coagulation

  16. Combustion Products. Fly-ash vs. bottom-ash 150 PAHs With 2 – 7 rings

  17. Particulate air quality in major world cities. Values are annual PM10 means. Horizontal line is WHO air quality guideline

  18. NASA satelite image ogNox from ships

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