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

transcript

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

In China 2000 years ago the LoessIn China 2000 years ago the LoessPlateau was the cradle of ancient ChinesePlateau was the cradle of ancient Chinesecivilization. Deforestation due to:civilization. Deforestation due to:

FirewoodFirewood collectioncollection Charcoal making Charcoal making Creation of farm landCreation of farm land Brick makingBrick making

resulted in a much drier and lessresulted in a much drier and lessproductive climateproductive 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)

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

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

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

Exposures are indoors as well as outdoors Picture by Kirk Smith, India, early 1980s

After a few hours

Acute Respiratory Infections/6 month in Rural Nepal Infants vs. time Near Stove

(M. R. Panday, 1984)

hoursnear stove

Mild Moderate Severe

0 to 0.9 1.7 0.3 0.05

1 to 1.9 2.1 0.5 0.08

2 to 3.9 2.3 0.6 0.7

4+ 1.8 1.0 2.8

Acute Respiratory Infections in Rural Nepal Infants vs. time Near Stove

hoursnear stove

0 to 0.9 1.7 0.3 0.05

1 to 1.9 2.1 0.5 0.08

2 to 3.9 2.3 0.6 0.7

4+ 1.8 1.0 2.8

Acute Respiratory Infections in Rural Nepal Infants vs. time Near Stove

hoursnear stove

0 to 0.9 1.7 0.3 0.05

1 to 1.9 2.1 0.5 0.08

2 to 3.9 2.3 0.6 0.7

4+ 1.8 1.0 2.8

Comparative ParticulateConcentrations in g/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

• Polynuclear aromatic hydrocarbons (PAH)

• Chlorinated dioxins and furans• Aldehydes and carbonyl compounds

Polynuclear Aromatic Hydrocarbons (PAH)

as a class of compounds are considered as a class of compounds are considered potential carcinogenspotential carcinogens

Combustion Formation of PAHBadger and Spotswood 1960

(I) (II) (III) (IV)

(VII) (VI) (V)

Benzo a Pyrene

Combustion Formation of Dioxins from Polychlorinated phenol

PolychlorinatedPhenol

OHC ly

Chlorinated dibenzo dioxin

C lx C lx O

Shaub & Tsang, ES&T 1983.

Fresh wood soot in outdoor chambers (0.5 m scale

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

particle

toxic gas

Langmuirian Adsorption (1918)

surface

• = fraction of total sites occupied• Rateon= kon (Pg) (1- );• Rateoff= koff ;• kon/koff= Keq

Langmuirian Isotherm

• if Keq Cgas<< 1; = Keq Cgas

= 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

moles occupiedsites V

total moles sites V

# /geqPK

Junge (1977)

A vapor pressure calculation for the liquid vapor for anthracene

ln ( ) . (ln )]PTT

o b b 19 1 8 5

Tb= 198 + Tb ; 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, lnPo

L = -12.76; p = 2.87 x10-6atm = 0.0022 torr

anthracene

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 0.35m, Bangkok =0.25m

Yamasaki et al.(1982)• Langmuirian adsorption•

• Assumes total # sites TSP (particle conc)

• log Ky = -a(1/T)+ b

part TSPy [ ]

Yamasaki (1982)• Collects Hi-vol filters+PUF• Analyzes for PAHs

filter

log Ky

1/Tx1000

Yamasaki’s relationship

• This gives a log Ky = -a(1/T)+ b which 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

TSP/]PAH[]PAH[

Comparison of Yamasaki predicted vs measured

Application of this theory

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.

UNC 25m3Teflon Film Chambers

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.

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

38oC 228 105 0.512

20oC 38 381 0.366

30oC ? 440 0.832

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

So what do we do??lnKy = -a(1/T)+ bTemp is in Kelven

XAD-2 (Gas) Filter TSP Ky 1/oK lnKyng/m3 ng/m3mg/m3 (temp)

oC K38 311 228 105 0.512 1.112 0.0032 0.10620 293 38 381 0.366 0.037 0.0034 -3.310

30 303 ? 440 0.832 ? 0.0033

lnKy = -a(1/T)+ b

TSP/]PAH[]PAH[

PAHGas PAHpart

y = -17295x + 55.716

R2 = 1

0.0032 0.00325 0.0033 0.00335 0.0034 0.00345

log Kp = -log Po(L) + const.

Kp= part/(gasxTSP)

log Po(L)

log Kp

slope = -1

Ambient data of Pankow and Bidleman

PAHs, alkaneschlorinated organics

For liquid like particles partitioning coefficient, Kp, is:

• Kip = 760 RT fomx10-6/{iPLtorriWavg}

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

• C= log [fom (7.501 RT)/ (106 Mwom)]

fom = fraction of particle organic mass Mwom = avg. Mw of om in the particle

Calculating Activity Coefs, i

• RT lniom= iV[(omd - id)2 +ib(omp - ip)2

+ ib(omh - ih)2] + RT [ln(iV/Vom) +1- iV/Vom]

• Vom is the molar volume of the mix

s are solubility parameters

d = Fd,j / iV

Partitioning & uptake by the lungs

• Nicotine (Pankow’s group)

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 3 and much of the nicotine exists in the acidified form on particles.

Nicotine

• 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.

• 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

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

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 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 emissions2. atmospheric reactions3. re-entrainment

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

• 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

Often when we measure particles they cover a large range of sizes

The normal distribution

exp)x(freq/

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

10-31-05 number

10 100 1000

The log normal distribution

Aerodynamic diameters of some particles

• tobacco smoke 0.25 m• ammonium chloride 0.1• flour dust 15- 20• fogs1- 5• pollens 15- 70• talc 10• photochemical aerosols 0.01-1

Aerosol exposures

Indoors

Outdoors

Work place

Aerosol exposures

Indoors (90% of our time)

– ventilation systems

– mechanically re-entrain particles (dust mites)

– cooking

Indoor activities generate particles

Activities that generate aerosols in Kamens home

Cooking stir-fried vegetables: Kamens house, 1987, EAA data

Vacuuming in Kamens House

Kamens house at night

How do particle sizes distribute in the atmosphere??

.3-.8 um

4-10 um

Particle samplers often collect particles smaller than a given size

• PM10 is defined as particles with diameters < 10 m.

• It is measured in units of g/m3 , typically by pulling air through filters.

• PM2.5 is defined as particles with diameters < 2.5 m

• 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???

Naso-oro-pharyngo-

Tracheo-bronchial

Alveolar

Why is this important???

Where do particles deposit??

Large particles deposit in the Naso-oro-pharyngo- region

Very fine particles (< 0.01 m) deposit in the Tracheo-bronchial

About 15-20% of the particles between 0.1 and 1 m deposit in the Alveolar region

How do particles distribute in the atmosphere??

.3-.8 um

4-10 um

Aerodynamic diameters of some particles

• tobacco smoke 0.25 m• 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

Urban Particle Exposure and its Association with Mortality and Morbidity

Killer Particles

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:• 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

2.5 m particle conc. in g/m3

10 20 30 40

mortality ratio

• 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)

• looked at 151 cities with different annual PM2.5 concentrations in 1980

• 552,138 mostly white adults

y = 6.9492x + 695.51

R2 = 0.426

0 10 20 30 40

2.5 m particle conc. in g/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

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

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

Smokers– women 1.16– men 1.18

NEVER SMOKED– women 1.22– men 1.14

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

• 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

The Pope et al. study concludes that:

• Typically they find the strongest relationship with fine particles and sulfate aerosols

• There is usually an association with all particles < 10 or 15 m, but it is not as strong as with fine particles

• Less of a relationship with aerosol acidity and almost none for O3 CO, NOx

There are other studies of this type

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

• 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%

• 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 at 65 g/m3 for 24 hours, not to exceed the 3rd highest value in 3 years; sampling ~1 time per week

These types of studies

Why is there a linear mortality rate response to particulate matter

and what is the mechanism??

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 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

Drop in U.S. air pollution linked to longer life-spans

Americans are living longer because the air they breathe is getting cleaner, a new study suggests. The average drop in pollution seen across 51 metropolitan areas between 1980 and 2000 appears to have added nearly five more months to people's lives, according to a study published Wednesday in The New England Journal of Medicine (Pope et. al, 2008.)

Many other factors can boost life expectancy, such as increases in income and education and reductions in smoking prevalence, so the researchers used statistical techniques to control for these and other relevant factors.

After this adjustment, they found that the effect of air pollution reduction remained; for every 10 microgram per cubic meter decrease in fine-particulate air pollution, life expectancies rose by about seven months. Pollution levels averaged about 21 micrograms per cubic meter in 1979-1983 and had fallen to an average of 14 micrograms per cubic meter by 1999-2000.

• 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

PM10 concentrations change with the seasons

Jan Mar May Jul Sep Nov

• 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

• 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

• Saturation sampler for PM2.5 or PM10

lunchon/off digital timer

rotameter

Battery

47mm filter holder

PM2.5 or PM10 inlet

• It can be hung or strapped to a post

Battery

So how do these samplers work??

Sizing particles with impactors

Impactors bring aerosols through a jet

The particles and air speed up as they go through the small orifice

• A disk or plate is place down stream of the jet

• The disk has grease or oil on the surface

• Depending on the speed through the jet, large particles will hit the disk, while small particles follow the air around the disk

Filter

• 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

P Tambcal amb

amb cal Qstd m

ambamb stdI

• 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

• 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

How do the samplers compare to each other when they are sampling in the same location ??

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

6 2 4 1 5 3Pump ID#

average 121 ug/m3

2 x % std 8.4%

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 )

ChiangMai

12-Ma20-Ma

28-Ma05-Ap

13-Ap21-Ap

29-Ap05/07

PM2.5 concentrations

12-Ma20-Ma

28-Ma05-Ap

13-Ap21-Ap

29-Ap05/07

PM2.5 standard Nui

12-Ma19-Ma

26-Ma02-Ap

09-Ap16-Ap

23-Ap30-Ap

05/0705/14

Usanee

12-Ma20-Ma

28-Ma05-Ap

13-Ap21-Ap

29-Ap05/07

Usanee PM2.5 standard

12-Ma19-Ma

26-Ma02-Ap

09-Ap16-Ap

23-Ap30-Ap

05/0705/14

12-Ma19-Ma

26-Ma02-Ap

09-Ap16-Ap

23-Ap30-Ap

05/0705/14

PM2.5 Standard Galae

How do the samplers at the different sampling locations compare ??

ChiangMai

12-Ma19-Ma

26-Ma02-Ap

09-Ap16-Ap

23-Ap30-Ap

05/0705/14

Usanee Kalae sndok2.5 Nui

When we sampled for more than one year

winter

Summer

winter

Summer

Chiang Mai Forest Fire Control Unit’s show the following number of fires

1998 1999

Dec 0 10

Jan 63 361

Feb 647 1699

Mar 1214 949

Apr 241 943

May 5 28

Jun-Nov 0 0

Winter Summer

Mixing height in meters (afternoon)

900 1400

Avg Wind speed

3.3 5.2

Temp (oC)

(avg high/low)

30/17 35/25

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.

Mar 98 Apr May Jun Jul Aug Sep

Mutagenicity vs. PM 2.5

PM 2.5 level g/m3

His + of TA100/plate

ChiangMai

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.

Recommendations? 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!!

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

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