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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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Fine atmospheric particles do we need to worry about them

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


Fine atmospheric particles do we need to worry about them

  • Almost all combustion leads to the formation of fine particles


Mastery of fire

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

Ultimately we learned how to use fire to clear land for crops


Fine atmospheric particles do we need to worry about them

In China 2000 years ago the Loess

Plateau was the cradle of ancient Chinese

civilization. Deforestation due to:

Firewoodcollection Charcoal making

Creation of farm land

Brick making

resulted in a much drier and less

productive climate


Fine atmospheric particles do we need to worry about them

  • 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)


Fine atmospheric particles do we need to worry about them

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


Fine atmospheric particles do we need to worry about them

  • 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

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


After a few hours

After a few hours


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)


Acute respiratory infections in rural nepal infants vs time near stove m r panday 1984

Acute Respiratory Infections in Rural Nepal Infants vs. time Near Stove (M. R. Panday, 1984)


Acute respiratory infections in rural nepal infants vs time near stove m r panday 19841

Acute Respiratory Infections 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 village1,000(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


Fine atmospheric particles do we need to worry about them

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

O

H

C

l

x

.

OH

Flame

C

l

x

.

O

O

H

+

Polychlorinated

Phenol

C

l

y

O

+ OH

O

C

l

y

O

C

l

x

O

H

C

l

x

C

l

y

Chlorinated dibenzo dioxin

Shaub & Tsang, ES&T 1983.


Fine atmospheric particles do we need to worry about them

Fresh wood soot in outdoor chambers (0.5 mm scale


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

particle


Langmuirian adsorption 1918

Langmuirian Adsorption (1918)

gas

surface

  •  = 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


Fine atmospheric particles do we need to worry about them

anthracene

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)

PhenPyrene BaP

8x10-46x10-52x10-7

10g/m30.22 91

100g/m33.123 99

500g/m31868100

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

filter

BaA

log Ky

PUF

1/Tx1000

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


Fine atmospheric particles do we need to worry about them

Comparison of Yamasaki predicted vs measured


Fine atmospheric particles do we need to worry about them

Application of this theory


Fine atmospheric particles do we need to worry about them

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 25m 3 teflon film chambers

UNC 25m3Teflon Film Chambers


Fine atmospheric particles do we need to worry about them

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.


Fine atmospheric particles do we need to worry about them

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

Temp gas (PUF)particle (filter)TSPng/m3ng/m3mg/m3

38oC2281050.51220oC383810.366 30oC?4400.832

So what do we do??

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


Fine atmospheric particles do we need to worry about them

PAHGas

PAHpart

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.


Nicotine

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.


Fine atmospheric particles do we need to worry about them

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 emissions2. atmospheric reactions3. re-entrainment


What are some of the terms used to describe aerosols

What are some of the terms used to describe aerosols?


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


Fine atmospheric particles do we need to worry about them

  • Density = mass/volumeDensityH20 = 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

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


The normal distribution

The normal distribution


Fine atmospheric particles do we need to worry about them

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


The log normal distribution

The log normal distribution


Aerodynamic diameters of some particles

Aerodynamic diameters of some particles

  • tobacco smoke 0.25 mm

  • ammonium chloride 0.1

  • flour dust15- 20

  • fogs1- 5

  • pollens15- 70

  • talc10

  • 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


Fine atmospheric particles do we need to worry about them

Indoor activities generate particles


Activities that generate aerosols in kamens home

Activities that generate aerosols in Kamens home


Cooking stir fried vegetables kamens house 1987 eaa data

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


Vacuuming in kamens house

Vacuuming in Kamens House


Kamens house at night

Kamens house at night


How do particle sizes distribute in the atmosphere

How do particle sizes distribute in the atmosphere??


How do particle sizes distribute in the atmosphere1

How do particle sizes distribute in the atmosphere??

.3-.8 um

4-10 um


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


Fine atmospheric particles do we need to worry about them

  • 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


Fine atmospheric particles do we need to worry about them

Why is this important???


Fine atmospheric particles do we need to worry about them

Why is this important???

Naso-oro-pharyngo-

Tracheo-bronchial

Alveolar


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


How do particles distribute in the atmosphere

How do particles distribute in the atmosphere??

.3-.8 um

4-10 um


Aerodynamic diameters of some particles1

Aerodynamic diameters of some particles

  • tobacco smoke 0.25 mm

  • ammonium chloride 0.1

  • flour dust15- 20

  • fogs1- 5

  • pollens15- 70

  • talc10

  • photochemical aerosols 0.01-1

  • Car exhaust 0.1- 0.3


Fine atmospheric particles do we need to worry about them

  • Urban Particle Exposure and its Association with Mortality and Morbidity


Fine atmospheric particles do we need to worry about them

Killer Particles


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

1.3

1.2

mortality ratio

1.1

1.0

10203040

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


Fine atmospheric particles do we need to worry about them

Deaths/10000

2.5 mm particle conc. in mg/m3


Fine atmospheric particles do we need to worry about them

  • 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


Fine atmospheric particles do we need to worry about them

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


Fine atmospheric particles do we need to worry about them

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

Smokers

  • women 1.16

  • men1.18

    NEVER SMOKED

  • women 1.22

  • men1.14


Fine atmospheric particles do we need to worry about them

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


Fine atmospheric particles do we need to worry about them

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


Fine atmospheric particles do we need to worry about them

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


Fine atmospheric particles do we need to worry about them

  • 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


Fine atmospheric particles do we need to worry about them

  • Hospital admissions for respiratory and cardiovascular illness are higher when PM10 concentrations are higher


Fine atmospheric particles do we need to worry about them

  • 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


Fine atmospheric particles do we need to worry about them

  • 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%


Fine atmospheric particles do we need to worry about them

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


Why is there a linear mortality rate response to particulate matter and what is the mechanism

Why is there a linear mortality rate response to particulate matterand what is the mechanism??


Fine atmospheric particles do we need to worry about them

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


Fine atmospheric particles do we need to worry about them

  • 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.

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.)


Fine atmospheric particles do we need to worry about them

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.


Fine atmospheric particles do we need to worry about them

  • ChiangMai, Thailand

  • Do we see the same kinds of particle health responses in northern Thai Populations??


Fine atmospheric particles do we need to worry about them

  • Currently, there are only a few studies which relate PM2.5 on a daily basis to mortality and morbidity


Fine atmospheric particles do we need to worry about them

  • 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

PM10 concentrations change with the seasons


Fine atmospheric particles do we need to worry about them

  • 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


Fine atmospheric particles do we need to worry about them

PM2.5 or PM10 inlet

  • Saturation sampler for PM2.5 or PM10

47mm filter holder

pump

rotameter

on/off digital timer

lunch

Battery

18cm


Fine atmospheric particles do we need to worry about them

  • It can be hung or strapped to a post

pump

Battery

~18cm


So how do these samplers work

So how do these samplers work??


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

Filter

  • A filter is placed under the disk to collect particles that do not hit the disk


Fine atmospheric particles do we need to worry about them

  • 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


Fine atmospheric particles do we need to worry about them

  • 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


Fine atmospheric particles do we need to worry about them

  • 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


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

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


Fine atmospheric particles do we need to worry about them

We located 6 samplers on the 2nd floor outside porch of Nui’s house and sampled for 24 hours on March 1, 1998


Fine atmospheric particles do we need to worry about them

We located 6 samplers on 2nd floor outside porch of Nui’s house and sampled for 24 hours on March 1, 1998


Fine atmospheric particles do we need to worry about them

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 )


Fine atmospheric particles do we need to worry about them

ChiangMai


How do the samplers at the different sampling locations compare

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


Fine atmospheric particles do we need to worry about them

ChiangMai


When we sampled for more than one year

When we sampled for more than one year

winter

winter

Summer

Summer


Fine atmospheric particles do we need to worry about them

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


Fine atmospheric particles do we need to worry about them

PM 2.5 level mg/m3

His + of TA100/plate

Mutagenicity vs. PM 2.5

Mar 98

Apr

May

Jun

Jul

Aug

Sep

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.


Fine atmospheric particles do we need to worry about them

ChiangMai


Fine atmospheric particles do we need to worry about them

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.


Fine atmospheric particles do we need to worry about them

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

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!!


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