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Fine Atmospheric Particles: Do we need to worry about them??

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Fine Atmospheric Particles: Do we need to worry about them??. Almost all combustion leads to the formation of fine particles. Mastery of Fire. 400,000 years ago in Europe 100,000 years ago in Africa M. N. Cohne, 1977. Ultimately we learned how to use fire to clear land for crops.

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mastery of fire

Mastery of Fire

400,000 years ago in Europe

100,000 years ago in Africa

M. N. Cohne, 1977


In China 2000 years ago the Loess

Plateau was the cradle of ancient Chinese

civilization. Deforestation due to:

Firewood collection Charcoal making

Creation of farm land

Brick making

resulted in a much drier and less

productive climate

North American Indians used to burn forested areas to promote the growth of food ”sprouts”
  • In Mexico deforestation often lead to soil erosion and drier climates (800-1400 before present-BP)

When fire was brought inside the home very large smoke exposures resulted:

  • These exposures are often much higher in the developing world than in the industrialized world
  • Women tend to spend more time around unvented fires than men
In Nepal females and their very young children receive much higher exposures to indoor fires than males (Kirk Smith, 1983)
  • Average cooking time is 2.8 hours
  • Prevalence of chronic bronchitis is related to hours spent near the stove
acute respiratory infections 6 month in rural nepal infants vs time near stove m r panday 1984
Acute Respiratory Infections/6 month in Rural Nepal Infants vs. time Near Stove (M. R. Panday, 1984)
comparative particulate concentrations in m g m 3
Comparative ParticulateConcentrations in mg/m3
  • U.S. Standard (PM2.5) 65
  • Sydney (1996) ~25
  • Traffic- Denmark 60
  • London Smog (1952) 4,500
  • Muese, Belgium 12,500
  • Indian village 1,000(Indoors ) 56,000
  • Malaysia (1997, PM2.5) 800
  • Thailand (1998, PM2.5) 300
combustion forms a host of toxics that are associated with soot particles
Combustion forms a host of toxics that are associated with soot particles
  • Polynuclear aromatic hydrocarbons (PAH)
  • Chlorinated dioxins and furans
  • Aldehydes and carbonyl compounds

Polynuclear Aromatic Hydrocarbons (PAH)

as a class of compounds are considered potential carcinogens

combustion formation of pah
Combustion Formation of PAH

Badger and Spotswood 1960

combustion formation of dioxins from polychlorinated phenol
Combustion Formation of Dioxins from Polychlorinated phenol























+ OH

















Chlorinated dibenzo dioxin

Shaub & Tsang, ES&T 1983.

many of these compounds exist as a free gas and on particles this influences
Many of these compounds exist as a free gas and on particles. This influences:
  • how they will be deposited on the earth's surface
  • the types of chemical reactions they can undergo
  • the route by which they enter the food chain and are sorbed or deposited in the lungs
gas particle partitioning
Gas Particle Partitioning

toxic gas


langmuirian adsorption 1918
Langmuirian Adsorption (1918)



  •  = fraction of total sites occupied
  • Rateon= kon (Pg) (1- );
  • Rateoff= koff;
  • kon/koff= Keq
langmuirian isotherm
Langmuirian Isotherm
  • if Keq Cgas<< 1; = Keq Cgas
junge 1977
Junge (1977)
  •  = jcj /(Po + jcj)
      • = fraction in aerosol phase
      • Po= sat. vapor pressure of the pure compound
      • j = conc. of aerosol surface (cm2/cm3)
      • cj =const, bBET, moles of sites/cm2,temp
      • cj=RTNse(Qi-Ql)/RT


A vapor pressure calculation for the liquid vapor for anthracene

Tb= 198 + S DTb ; C14H18

anthracene has10, =CH- , carbons and each carbon = 26.73oK/carbon

It also has 4, =C< at 31.01OK/carbon

Tb = 198 + 267.3 + 124.04 = 589;

Published boiling point is = 613K

At 298K, lnPoL = -12.76; p = 2.87 x10-6atm = 0.0022 torr

percent in the aerosol phase at different aerosol concentrations 25 o c
Percent in the Aerosol Phase at Different Aerosol Concentrations (25oC)

Phen Pyrene BaP

8x10-4 6x10-5 2x10-7

10g/m3 0.2 2 91

100g/m3 3.1 23 99

500g/m3 18 68 100

rural= 0.5m, high urban 0.35m, Bangkok =0.25m

yamasaki et al 1982
Yamasaki et al.(1982)
  • Langmuirian adsorption
  • Assumes total # sites  TSP (particle conc)
  • log Ky = -a(1/T)+ b
yamasaki 1982



log Ky



Yamasaki (1982)
  • Collects Hi-vol filters+PUF
  • Analyzes for PAHs
yamasaki s relationship
Yamasaki’s relationship
  • This gives a log Ky = -a(1/T)+ bwhich is compound specific
  • Ideally from the regression values of a and b, one can estimate the partitioning of a given compound in any atmosphere at a given temp. and TSP

A number of years ago we conducted two wood smoke experiments in our Teflon film chambers to evaluate the stability of 9,10 anthraquinone.

The average chamber temperature for one experiment was 20oC and the other was 38oC. A third experiment was conducted at 30oC, but only filters were analyzed. Data from these experiments are given below.


Three years later it became very important to know the PUF (gas phase) and particle phase distribution of anthraquinone at the 30oC experiment.

It costs, however, 10,000 USD to re-run experiments.


9,10-anthraquinone data in the gas (PUF) and particle (filter) phases

Temp gas (PUF) particle (filter) TSP ng/m3 ng/m3 mg/m3

38oC 228 105 0.512 20oC 38 381 0.366 30oC ? 440 0.832

So what do we do??

lnKy = -a(1/T)+ bTemp is in Kelven




lnKy = -a(1/T)+ b

log k p log p o l const k p part gasxtsp

log Kp = -log Po(L) + const. Kp= part/(gasxTSP)

slope = -1

log Kp

  • Ambient data of Pankow and Bidleman
    • PAHs, alkanes
    • chlorinated organics

log Po(L)

for liquid like particles partitioning coefficient k p is
For liquid like particles partitioning coefficient, Kp, is:
  • Kip = 760 RT fomx10-6/{iPLtorrig MWavg}

log Kip= - log iPo(L) +C -log ig

  • C= log [fom (7.501 RT)/ (106Mwom)]
      • fom = fraction of particle organic mass
      • Mwom = avg. Mw of om in the particle
calculating activity coefs i g
Calculating Activity Coefs, ig
  • RT lnigom= iV[(omdd - idd)2 +ib(omdp - idp)2+ ib(omdh - idh)2] + RT [ln(iV/Vom) +1- iV/Vom]
  • Vom is the molar volume of the mix
  • ds are solubility parameters
  • dd = S Fd,j / iV
partitioning uptake by the lungs
Partitioning & uptake by the lungs
  • Nicotine (Pankow’s group)
uptake by the lungs nicotine
Uptake by the lungs (Nicotine)
  • Under normal circumstances Nicotine can exist as a neutral “free base” or as a protonated mono or di-acid and will appear predominately in the particle phase.
  • Typically cigarette smoke has pH values ³3 and much of the nicotine exists in the acidified form on particles.
  • The acidified form can not partition between the gas and particle phase.
  • If ammonia is added to the tobacco smoke, “as a flavor enhancement”, the pH increases moving the equilibrium on the particles from the mono-acid to the neutral form.

Impact and “advantages” of ammonia “flavor enhancement” on partitioning

  • In the neutral form nicotine can partition to the gas phase.
  • neutral nicotine can then be readily absorbed by the wet surface of the inner lung (Pankow’s group)
  • loss of nicotine to the lungs “pulls” more nicotine off the particles
what are aerosols
What are aerosols?
  • Aerosols are simply airborne particles
  • They can be solids or liquids or both
  • They can be generated from some of the following sources:
what are aerosols1
What are aerosols?
  • Aerosols are simply airborne particles
  • They can be solids or liquids or both
  • They can be generated from some of the following sources: 1. combustion emissions 2. atmospheric reactions 3. re-entrainment
what are some of the terms used to describe aerosols1
What are some of the terms used to describe aerosols?
  • Diameters are usually used to describe aerosol sizes, but aerosols have different shapes.
often particles are sized by their aerodynamic diameter
Often particles are sized by their aerodynamic diameter
  • The aerodynamic diameter of a particle is defined as the diameter of an equivalent spherical particle (of unit density) which has the same settling velocity.
  • It is possible to calculate the settling velocity of a spherical particle with a density =1
Density = mass/volume DensityH20 = 1gram/cm3= 1
  • Terminal Settling velocity (Vs ) is the rate that a particle falls due to gravity
A Log normal distribution is often applied to the size data by plotting the logs of the particles size vs frequency

The log of the geometric mean is

log diameter

aerodynamic diameters of some particles
Aerodynamic diameters of some particles
  • tobacco smoke 0.25 mm
  • ammonium chloride 0.1
  • flour dust 15- 20
  • fogs 1- 5
  • pollens 15- 70
  • talc 10
  • photochemical aerosols 0.01-1
aerosol exposures
Aerosol exposures
  • Indoors
  • Outdoors
  • Cars
  • Work place
aerosol exposures1
Aerosol exposures
  • Indoors (90% of our time)
    • ventilation systems
    • mechanically re-entrain particles (dust mites)
    • cooking
particle samplers often collect particles smaller than a given size
Particle samplers often collect particles smaller than a given size
  • PM10 is defined as particles with diameters < 10 mm.
  • It is measured in units of mg/m3 , typically by pulling air through filters.
  • PM2.5 is defined as particles with diameters < 2.5 mm
The choice of measuring at exactly PM10 or PM2.5 is somewhat arbitrary
  • Some people argue for a PM1.0
  • Until recently only PM10 has been measured in Thailand

Why is this important???




where do particles deposit
Where do particles deposit??
  • Large particles deposit in the Naso-oro-pharyngo- region
  • Very fine particles (< 0.01 mm) deposit in the Tracheo-bronchial
  • About 15-20% of the particles between 0.1 and 1 mm deposit in the Alveolar region
aerodynamic diameters of some particles1
Aerodynamic diameters of some particles
  • tobacco smoke 0.25 mm
  • ammonium chloride 0.1
  • flour dust 15- 20
  • fogs 1- 5
  • pollens 15- 70
  • talc 10
  • photochemical aerosols 0.01-1
  • Car exhaust 0.1- 0.3
recent particle health studies
Recent Particle Health Studies
  • Dockery et al., N. Eng .J. Med, vol 329, p1753, 1993)
  • looked at 6 American cities with different annual PM2.5 concentrations
  • From 1974 to 1990, they followed 8111 males and females.
  • Subjects were 25-74 years old
mortality rates were estimated from
Mortality rates were estimated from:
  • Survival times (date of death minus the start date for that person in the study)
  • Raw mortality rates are computed, for each city, which are the number of deaths/year/100,000 people
  • These were adjusted for smoking, education, body mass index, and other risk factors
mortality vs particle exposure



mortality ratio



10 20 30 40

2.5 mm particle conc. in mg/m3

Mortality vs. particle exposure

On a mass basis urban fine particles may be more toxic than cigarette smoke

another study by pope et al am j crit care med vol 151 p669 1995
Another Study by (Pope et al., Am J. Crit. Care Med., vol 151, p669, 1995)
  • looked at 151 cities with different annual PM2.5 concentrations in 1980
  • 552,138 mostly white adults


2.5 mm particle conc. in mg/m3

Used a Cox multiple regression analysis proportional hazards model
  • Fleming, T.R. and D.P Harrington Counting Processes and Survival Analysis. John Wiley, New York,1991
  • SAS Technical Report P-217; SAS/STAT Software: The PHREG Procedure. Version 6; SAS Institute, Cary NC,USA

Using their model they could look at the risks associated with:

  • age
  • sex
  • race
  • cigarette smoking
  • passive smoke exposure
  • body mass
  • alcohol intake
  • education
  • occupational exposure

Adjusted Mortality Risk Ratios for exposure to 24.5 mg/m3 fine particles


  • women 1.16
  • men 1.18


  • women 1.22
  • men 1.14

The Pope et al. study concludes that:

  • Risks for increased pollution exposure were the same for smokers and non smokers
  • The association between pollution and mortality was not very sensitive to: occupation, education, body mass, alcohol, and temperature
  • occupational differences between men and women did not matter

There are other studies of this type

  • Typically they find the strongest relationship with fine particles and sulfate aerosols
  • There is usually an association with all particles < 10 or 15 mm,but it is not as strong as with fine particles
  • Less of a relationship with aerosol acidity and almost none for O3CO, NOx

The latest interpretations do not find the strong relationship that was observed back in 1993, but still report a significant particle exposure and mortality relationship (this is what is in your book chapter, Figure 2-21)

in a particle study in bangkok 1998
In A Particle Study in Bangkok, 1998
  • health effects were associated with airborne particles
  • They measured PM10
  • Particle concentrations in Bangkok tend to be higher than in other cities around the world
The results suggest that at current PM10 concentrations in Bangkok, there are between 1,000 and 2,000 premature deaths each year
  • These deaths are attributable to short-term exposures to outdoor airborne particulate matter
  • This represents about 5% to 10% of all recorded deaths in Bangkok
Hospital admissions for respiratory and cardiovascular illness are higher when PM10 concentrations are higher
For highly exposed adults, during the winter months, who do not spend much time in air-conditioned environments,
  • outdoor PM10 was associated with twice the incidence of acute respiratory symptoms than was predicted when there is no pollution
For adults who spend substantial time in air-conditioned environments, the average outdoor particulate matter during the winter months still increased their symptoms by about 20%

These types of studies

  • suggest a 1-2% increase in the mortality rate for every 10 ug/m3 of fine particulate matter (Schwartz et al, 1996)
  • Contributed to the US EPA setting a PM2.5 ambient particle standard at65 mg/m3 for 24 hours, not to exceed the 3rd highest value in 3 years; sampling ~1 time per week
Samet et al. at UNC have recently exposed human airway epithelial cells to residual oil fly ash (ROFA) particles
  • cells secreted prostaglandins
  • Prostaglandins are a class of potent inflammatory mediators which play a role in inflammatory, immune and functional responses in the lung
human volunteers had inert fe 2 o 3 particles introduced into their lungs lay et al 1995
Human volunteers had inert Fe2O3 particles introduced into their lungs (Lay et al, 1995)
  • Produced a subclinical inflammatory response in the first 24-48 hours
  • Influx of macrophages and neutrophils onto the alveolar spaces as assessed by bronchoalveolar lavage
  • Protein releases suggests alveolar epithelial damage
Leakage of plasma protein and fluids in to alveolar space alters gas exchange of injured tissue
  • This is not a problem for a healthy person
  • people with compromised cardiac or pulmonary systems, however, may not be able to compensate or tolerate even mild exposures
ChiangMai, Thailand
  • Do we see the same kinds of particle health responses in northern Thai Populations??
Currently, there are only a few studies which relate PM2.5 on a daily basis to mortality and morbidity
Chiang Mai was selected because it has high average fine particle concentrations
  • The concentrations change significantly with the seasons
  • We wanted to see if mortality would track the changes in particle concentrations
The population of the city of Chiang Mai is ~170,000 people
  • If the average death rate is 750 people per 100,000 people per year
  • This will give on average 3 or 4 deaths per day
in 1998 the us epa provided cmu with particle samplers
IN 1998, The US EPA provided CMU with particle samplers
  • 8 saturation samplers with batteries;
  • more than 1000 Teflon filters; these can be used to obtain particle mass
  • Flow calibration gear
  • 7- small samplers for personal monitoring

PM2.5 or PM10 inlet

  • Saturation sampler for PM2.5 or PM10

47mm filter holder



on/off digital timer




sizing particles with impactors
Sizing particles with impactors
  • Impactors bring aerosols through a jet
  • The particles and air speed up as they go through the small orifice
sizing particles with impactors1
Sizing particles with impactors
  • Impactors bring aerosols through a jetdisk
  • A disk or plate is place down stream of the jet
sizing particles with impactors2
Sizing particles with impactors
  • Impactors bring aerosols through a jet
  • The disk has grease or oil on the surface
sizing particles with impactors3
Sizing particles with impactors
  • Depending on the speed through the jet, large particles will hit the disk, while small particles follow the air around the disk
sizing particles with impactors4
Sizing particles with impactors


  • A filter is placed under the disk to collect particles that do not hit the disk
From this you can see the flow rate is very important.
  • The EPA samplers must flow at 5 liters/min
  • If we calibrate them in the lab at one temperature we must estimate the temperature, and pressure when we sample outside
From this you can see the flow rate is very important.
  • The EPA samplers must flow at 5 liters/min
  • When we calibrated them in the lab at one temperature, we had to estimate the temperature and pressure when we sampled outside
We changed filters and the battery once per day, 7 days / week
  • Filters are weighed on a 5 or 6 place balance and stored in plastic petri dishes
located samplers
Located samplers
  • residential area in the city- PM2.5
  • 5th roof top- urban sample not influenced by different sources- PM2.5 & PM10
  • high population density area (down town market?)- PM2.5
  • relatively clean air- PM2.5
We located 6 samplers on the 2nd floor outside porch of Nui’s house and sampled for 24 hours on March 1, 1998
We located 6 samplers on 2nd floor outside porch of Nui’s house and sampled for 24 hours on March 1, 1998

average 121 ug/m3

2 x % std 8.4%

four different sampling locations were selected for monitoring pm2 5
Four different sampling locations were selected for monitoring PM2.5
  • Down town area (Nui’s house)
  • Residential area (Dr. Usanee’s house)
  • General city exposure (outside 5th floor of medical school)
  • Background (2nd floor -Galae )

PM 2.5 level mg/m3

His + of TA100/plate

Mutagenicity vs. PM 2.5

Mar 98







PM 2.5 levels and air-borne mutagenicity in Chiang Mai ambient air at different monitoring sites in the same month. Bar graph = PM 2.5 level at

= site 1, = site 2, = site 3, = site 4.

Line = mutagenicity at

= site 1, = site 2, = site 3, = site 4, spontaneous revertants have been substracted already.


If the downtown site, for example, “experienced” a slightly higher exposure to diesel exhaust which, is much more mutagenic than wood smoke, the PM levels would appear similar, but the mutagenicity would be influenced by the diesel particles and appear higher.


A high prevalence of asthma in children living in Chiang Mai has been reported.

At the present time, however, it is difficult without further study to know if open burning is exacerbating the asthma problem in Chiang Mai.

It would seem prudent, given the high fine particle concentrations, to curtail open burning as much as possible. Future studies should also attempt to identify compounds in Chiang Mai air that are potentially toxic to human health so that these may be used as bench marks for future control strategies.

  • 2 stroke motor cycles account for half of the motor vehicles and can emit more than 10 times the amount that gasoline cars do. We need to go to 4 stroke engines
  • Replace small diesel pick-up trucks gasoline engine pick-up trucks-maintenance off all vehicles
  • Control open burning!!