Temporal and spatial variations of lead in air and in surface dust — Implications for monitoring

37

The Science of the Total Environment. 33 (1984) 37-48 Elsevier Science Publishers B.V., Amsterdam -Printed in The Netherlands

TEMPORAL IN AIR AND

M.J. Duggan, Environmental Greater London Council,

AN0 SPATIAL VARIATIONS OF LEA0 IN SURFACE DUST - IMPLICATIONS FOR MONITORING

Sciences County Hall,

Division, LONDON

Scientific SE1 7PB

Services

Branch,

ABSTRACT Before embarking on any pollution monitoring programme aimed at assessing the exposure of a population group, decisions must be taken as to the duration of the measurements and the locations of the sampling sites. These decisions require a knowledge of the way that pollution concentrations vary with time and with distance, and some incomplete but useful data obtained in the course of our work is presented here. Seasonal variations in the concentrations of airborne lead show a consistent pattern but there is no evidence of a seasonal variation in the concentrations of lead in dust. The short-term variations in airborne and dust lead are rather similar. Spatial variations over short distances (a few metres) are likely to be more important for dust-lead than for airborne lead, but it is quite possible to obtain representative dust-lead values by means of large-area sampling. There is little reason to dismiss as impractical, on the grounds of excessive temporal or spatial variations, the assessment of pollution from lead in surface dust.

INTRODUCTION Measurements and

for

us the

people.

of environmental most

common

In principle,

the

concerned

in the

area

value

some

standard

with

is needed. varies problem if the

of where, measured

example CEC

with

the

value rather

0048-9697/84/$03.00

the

over

concentration

limit

task

is rarely time

period, are

then

1.9 pg/m3

of the

0 1984

Elsevier

The

lead

The

standard

is being

the

consequences

are

likely

whether

or not

some

Publishers

difficulty

unusually

B.V.

will

a measured

important.

with

the

be more value;

by comparison

the

action probably

faced

and

pollutant

measured

or guideline

of reporting

of

the

concentration

assessed

to be substantial, become

Science

of the

compare

pollutant

of reasons

of a group

and so one is immediately

to the

measurements

a number

concentration

to decide

to sample.

close

for

exposure

and the,n

simple.

and with what

the

are,

in order

be made of the

- measure people

of airborne

of 2 pg/m3 than

the

may

assessment

is simple

or guideline

distance and

is the

the

concentrations

2.1 pg/m3

representativeness

task

where

In practice

sharply

pollution

one

accura’cy

acute

if for with

the

value and

of

38

Limited as short

resources

a period

that

some

with

distance

GLC

Scientific

knowledge and

of

but

we have

part

as a by-product

but

in order

of our

have

exposure

concentrations a monitoring

monitoring

be of

from

and

They

value

have

are

are

been

traffic-produced

to vary The

have

(and

indeed

for

service not

who

of this

obtained

technical

the

work

out

other

most

and

a complete

to carry

over

it follows

likely

of knowledge

therefore

to those

and

and

programme.

body

They

data.

sites

results,

pollutant

problem.

may

at as few

in planning

relevant

the

be taken representative

no comprehensive

long-term

of

nevertheless

to assess

in which

some

samples

obtaining

is essential

Branch

study

that

with

way

time

acquired

a systematic

results,

demand

the

with

Services

kind

from

usually

as is compatible

not

set

of

monitoring

forms

of)

pollution.

AIRBORNE

LEAD

Temporal

variations

The

hazard

long-term over

from

one

and

a lengthy

current

period

guidelines

guidelines CEC

for

limit

For

air

in the

increase

as the

variation

than

two point

ground),

and

total

‘summer’

on Table

during 1.

the

sites

of some

Hall

particulate

matter

(TSP).

as April

to September

winter

to

that

- one

then in the

monitor If ‘winter’ the summer

ratio

the

the

the [3].

throughout

the

period

is likely

to

seasonal

tend

to be higher

in

effect.

adjacent top

and quarter

of which

regular

of

GLC

averages,

[z],

pollutants this

at roof

routinely

3-month

size

is some

form the

a calender

the

There

other

by the

monitoring

is a

averaged

example, of

over

in an error,

we

the

pollutants

the

For

concentration

continuous

at County

kerb)

is reflected

value

to quantify

pollutants

concentration

in terms

mean

- levels

it is useful

the

are

decreases.

concentrations - and

[l]

result

the

lead.

mean

from

of sampling

monitoring

suspended and

is the

will

environmental of

This

is an annual

departure

2 m from

among

concentration shown

period

days.

in dust

lead

level

in summer

We have (sampling

March

any

other

environmental

lead

lead

airborne

reference

in airborne

winter

and

many

a knowledge

than

for

airborne for

sampling,

specified

and

for

lead

and

from

rather

standards

airborne

standard

to lead judged

- months

and

value

USEPA’s

exposure

so is best

to a major

level are

(about lead,

is defined of the over

one

30m

carbon

road above

as

October

average

lead

12 month

the

monoxide

period

to

is

39

TABLE

1

Winter/summer

ratio

for

airborne

lead

at County

Airborne

Hall

Lead

Date Roadside

Data

Winter

78179

1.47

Summer

78

1.20

over

a longer

These

are

presented

TABLE

2

Winter/Summer

period

are

in Table

ratios

= 1.23

0.54

= 1.65

0.33

available

for

carbon

monoxide

and

TSP.

2:

of carbon

Carbon Date

Rooftop

monoxide

and TSP

at County

Monoxide

Roadside

TSP

Rooftop

Hall

(gravimetric)

Roadside

Rooftop

Winter Summer

76177 77

4.48 3.50

= 1.28

2.30 1.22

= 1.89

61.3 56.2

= 1.09

43.5 39.4

= 1.10

Winter Summer

77178 77

3.98 3.50

= 1.14

1.72 1.22

= 1.41

69.7 56.2

= 1.24

50.3 39.4

= 1.28

Winter Summer

77178 78

3.98 4.07

= 0.98

1.72 1.85

= 0.93

69.7 57.3

= 1.22

50.3 38.5

z1.31

Winter Summer

78179 78

4.57 4.07

= 1.12

2.63 1.85

= 1.42

66.8 57.3

= 1.17

47.8 38.5

=1.24

Means

1.13

In a study carriageway period outskirts

at four

designed

1.38

to explore

we carried

out

points

in a field

of London.

These

the

1.18

fall

continuous

are

adjacent summarised

off

1.23

in pollution

sampling

with

of airborne’lesd

to Western in Table

Avenue 3.

distance for - a major

from

the

a 12 month road

on the

40 TABLE

3

Winter/summer

ratios

for

airborne

Airborne

are

70179 79

2.16 2.11

-1.20 1.08

the

numerators

derived

be of interest

may

monoxide

and pg/m3

It is evident distance

from pollutants.

major

contribution

roadside

and

any

correction

As well pollutants

particulate

months

with

of the

are weather

variations in Table

of filter

conditions found

4.

=2.03

which

the

ratios

units

are

ppm

The

the

ratio

to be the

pollutant

ratio

increases

major

- TSP

is small month

for

with

source

of all

- to which

close

to the

pattern

there

is a

or less

than

are

at roadside

week.

level,

week

the

sites

a ten

during

the for

presumably

or if the

for

lead

concentrations

example,

assessment

a period

to week

cannot

week

factor. monitoring

(and

many

which

are

of a new

of about

variations

be accounted

major

the

of airborne

However,

The and

to an annual to make

roadside.

concentration

continuously

marked

period

the

average

in, for

is to sample every

from

in the

long-term

about

be advisable

reference

variations.

procedure

probably

it would

distance

short-term

quite

(i.e

measurement

However,

it is the

sometimes

included.

0.71 ri35

lead.

is taken

at some

seasonal

usual

1OOm

from

winter/summer

a three

were

scheme,

a change

concentration

say,

made

of course

and our

management

the

making.

pollutants)

interest

local

being

the

for

Avenue

sources.

concentration

are

traffic

flow;

worth

as a regular there

of most

is least

denominators

for

traffic

non-traffic

from,

were

Western

1.00 = 1.47 0.68

therefore

and

that

concentrations,

if the

measurements

are

TSP

tables

effect

from

usually

from

30m

and

- if road

correction

is not

Avenue

distances

= 1.11

and for

the

source This

For

average

from the

three

given

= 1.02

tables,

other

at four

Western

10m

In all three

carbon

1.2)

lead

near

lm

Date Winter Summer

lead

3

in for

Some

by traffic examples period

are

41

TABLE

4

Temporal variations weeks) at several

Site

Earls Court Road Warwick Rd North Warwick Rd South Goodge St Wl York Rd SE1 Archway N19 CrystalOPalace Park Church Rd SE19 Westow Hill SE19

in the

averaqe

With

s.d.

V+

R*

1.41

0.56

0.40

3.9

1.90

0.44

0.23

2.4

1.52

0.58

0.38

3.5

1.05

0.27

0.25

2.3

1.39 1.39

0.39 0.42

0.28 0.30

2.9 2.6

0.28

0.09

0.32

4.0

1.90

0.72

0.38

4.0

1.32

0.23

0.17

2.0

variations

weekly

one or two periods

concentrations

of this

averages weeks

in Table

concentrations

mean lead cone pg/m3

+ V is the coefficient of variation + R is the range (highest/lowest

lowest

weekly

of lead

(10

consecutive

sites

is not 4 into of airborne

(s.d./mean) concentration)

magnitude

at any adequate. two

- a factor

one site

of up to 4 between

- it is clear

that

It is instructive

to divide

consecutive

5 week

periods

lead.

averages

are

These

the highest

a monitoring each

period of the

and to calculate shown

in Table

10 week the

5.

and of only

average

42 TABLE

5

The

variation

Site

of average

Average lead in two

It can

be seen

one site

to a month

or two,

In all this, any

other

which

can

it must

indeed

year

single

figure

that

can

Spatial

for

1.62

2.18

1.32

1.32

ratio

and

of changes

the

variations

less

flow

of airborne

and longer

From a month

or two

of

monitoring and

conditions, site.

The

long-term

the examples

(or of

value

to month

and weather

of the

extends

lead the

month

at a particular value

average

period

constant

by longer

week

the lower

results.

absolute

to week,

site.

- is the

monitoring

accurately

in traffic

than

and

the

from

a likely

at the of not

higher

concentration some

lead.

@g/m3)

misleading

the concentration

concentration

seasonal

grossly

is not

more

is to give

period

when

that site

be variations

investigator

the

that

to obtain

more

specify

between

suggests

be remembered

because

fully

a monitoring

correction

0.28

greatest

always

to year

average)

0.28

at a particular

will

ask of the

1.58 1.78 1.62 1.18 1.38 1.42

1.3 and this

be determined There

annual

the

of airborne

of airborne 5 week periods

1.24 2.02 1.42 0.92 1.40 1.36

one is unlikely

pollutant)

periods.

can

that

is about

concentrations

concentration consecutive

Earls Court Rd Warwick Rd N Warwick Rd S Goodge St Wl York Rd SE1 Archway N19 Crystal Palace Park Church Road SE19 Westow Hill SE19

at any

monthly

and

most

no

one

(preferably

given

above

- perhaps

it seems

coupled

with

with

distance

some

minimum.

variations

A few

studies

from

a major

highway

4,5,6

and 71.

They

Chamberlain’s 3 at 30m

from

of the decrease not tend

close

to show

summary

of some

the

of the

edge

in concentration to buildings a sharp, of the carriageway.

or other

of airborne roads

quasi-exponential data

suggests However,

have

lead been

decrease a decrease the

person

reported with

by a factor planning

[e.g

distance

e.g

of about the

43

monitoring

of

differences

lead

(8)

et the

from

at a point

62)

a short the

There

seem

are

incomplete

likely

compared

say

3m

distance

front

a major

are

kerbside

(b)

data

pollution

in concentration

(road-

they

with

compared a side

facing

side)

any

help

the

road

10m

road of

for

the

to know

what

sampling

pavement

the

rear

level

of a building

compared

with

building.

published

to provide

like example,

facade

above

or at

relevant

would

from,

building

with

down

to be hardly

urban

to arise

measurements,

answers

to

some

of

and

the

although

questions.

our

For

example,

(a)

In one

lead

for

London

several

the

building

3m

above

the

pavement

result

shown

by carbon

lower

than

set

of

(b)

We made

significant

Other

of about

there

are

too

(c)

The

ratio

of

neighbours,

of

relevant

about between systematic

20m

from

data

lm

must

its

distance

and

measurements

kerbside

also

at

facade

concentration

- on average

by a factor

of about

explicable)

pattern

more

by a factor

location

consistently

of about

0.7.

street

and was

was

in a different

at three a period

and

12m)

in the

surprisingly

from

- at road. 2.0

the front

The

with of

the

markedly

front/back

an overall the

decrease

and

A similar

also

the

rear ratio

average

and

gave

rear

We have of a run

in concentration

of

slight monoxide.

in city

streets,

of a building of

the

made

of 2 storey

varied

in the

no

picture.

dimensions

value

12m)

a very

gradients

a reliable

on the

and found

of carbon

vertical

front

8m and only

concentration

carriageway. and

weeks lead

to form

at

(lm,

several

small

literature

depend

heights

of

of airborne

concentrations

road

a major

and

the

(and

only,

level

the

concentration

monoxide

for

in the

pollutant

1.1

facade

pavement

of airborne

from

reverse

on average

carbon

reported

measurements

about

the

concentration

between

few

and

by the

which

a building

have

a major

its

concentration

curious

concentration

above - 2m

expectations,

measurements

of

5%

1.5m

pavement

weekly

0.7.

in the

[8,9]

but

bordering

for

simultaneous

(about authors

location

concentration,

difference

decrease

average

the

kerbside

more

but

facade

the

Against

- for

kerbside

factor

street-facing

the

made

monoxide

the

of

level.

measurements,

average

rear

than

was

measured

at a kerbside

at the

higher

The

we

weeks

facade

consistently 1.3.

street

building only

one

terrace

from

week

1.8.

We have

along

a minor

and series houses

to week not road

made (at

an

44 right

angles

to a major

been

reported

by Hickman

distance

than

buildings

in the

or other

concentration

Although with

that

the

For

than

about

limit

the

not

example,

the

once

area

from

for

major

the

of the

ground

again, are

what

there

are

of sampling at the

and third

of the

is about

floor

road,

30%.

of airborne

concentrations

a side

vicinity

edge

area

data

choice

to

the at the

in a rural

the

has

with

close

in concentration

differences

in the

not

carriageway

areas,

down

set of data decline

a road

of that

road

floor

and 10m

One

a smaller (i.e

the

as to make the

road.

60%

changes

in urban

or at the

However,

suggest

between

or at 3m

concentrations

results

about

so great

major

in a rural at 30m

difference

street,

the

et al was

carriageway

usually

pavement,

the

if the

suggest point

front

windows

is unlikely

and of a

to be more

of this

magnitude

become

of some

guideline,

standard

routes

and one which

or

value.

LEAD

IN DUST

Lead probably

in the

environment

important

for

However,

distances

and periods

taken

during

the

road;

they

samples past

of dust

are

spaced

concentration

three

sites

they

are

week

or two,

by means each

samples,

also

along

from

about

about

30 sets

of a broom sample. and have

and

We have

the

dust

assessment

via

of lead vary

dirty

is

hands.

in dust

so much

spatial

around

County

Hall

on the

pavement

should

of samples

measured

there

be different

over

being

not many

taken of about

only

lead

of them.

temporal

short

that

reason

out

each

year.

five

square

major

why

at another. Hall

also

several

About

2000

dust

metres other

the

The and

dust-

other

the

at intervals The

we

intervals

of a busy

County

is carried

but

variations

at regular

is no apparent

between

Sampling

an area

and

from

walkway

40 m apart.

dustpan,

are

and

pedestrian

size-fractionated

about

of the sites

40 m apart

a quiet about

by various of surface

concentrations

6 sites

Three

spaced

the

information

at one site

are

body

[ll].

some

2 years.

the

ingestion

that

because

of time

to obtain

reach is the

suggested

is difficult

In order have

can

children

it is sometimes

concentrations

for

so few

from

30%.

important

lead

studies

are

facing

example,

by Hickman

are

of a 2m wide

building

road

figure

distance

critical. rear

For

from

whose

corresponding

there

changes

distance

of a major

roads).

the

with

et al (10)

case

reported

carriageway;

lead

road)

River;

of a

is collected being

swept

metals

measurements

in the have

45 been

made

to date

work

can

be presented

Firstly,

how

is instructive samples Table

does

in order 4 for

are

still

concentration the

being

at any

coefficient

a comparison

measurements adjacent

3 sets

examined

TABLE

results

the

to make

weekly sites

first

the

analysed,

but

some

aspects

of the

here.

to calculate

pavement the

and

of 10 consecutive site

giving

of lead

in dust

vary

with

for

from

sets

the coefficient

week

of variation

lead

at roadside

sites.

major

were

considered

for

road

samplings 9 sets

(over

in all.

The

a period data

to week?

shown

given The

the

of about

are

It

of 10 consecutive

of airborne

to a busy

at each

one site

of variation

in

three

comparison

and

4 months)

in Table

6.

6

Variations

concentration

during

Value Parameter

periods

of parameter E

10 2570 700 0.27 2.0

n s.d. V R

s.d V R

10

3460 860 0.25 2.3

10 2360 1170 0.50 6.2

10 3230

10 2770

2.1 10

2150 i; ~g19

7200.33 3.1

R

dust-lead

8700.27 2.3

the number of samples in each set the average lead in dust concentration the coefficient of variation, sd/x the ratio of the highest to the lowest

Presumably increased,

but

V would with

concentrations

our

tend current are

10 2710 890 0.33 2.7

10

3350 1020 0.30 3.5

10

n

is is is is

F

2550 680 0.27

n

x IdI

n x V R

at site:

D

x I49

of 4 months

to decrease regime about

the

as the

and

8300.30 3.5

sd the standard

concentration swept

it can

be seen

same

as for

the

in each

area that

(and the

the

values

concentrations

deviation set. amount of V

of dust) for

of airborne

the

46

lead.

The

little

ranges

are

justification,

then,

measurements,

not

annual

distance

was

from of spatial

over

comparatively

idea

took

samples

about

6 weeks

school

was of the

pattern was

TABLE

7.

Spatial

and

sites

overall

the

total

would

variations

No. of Samples

of

ratio

lead

Lead in dust mean

was

not

the

significantly

on the

with

same

is a random

day, For

third

were

the

variation

results

separate

As

collected

in the

difficult

in one

about

sampling

made

and

road.

two

a considerable

example,

was

at

with A more

taken

playgrounds

the

those at the

concentration

on three

samples

than

of concentrations

decreasing

to a major

the

in Table

example,

higher

on occasions

reduction

given

sites

of a school the

During

grid.

consistently

of variation.

adjacent

permit,

a corresponding are

of

not

lead

there

For

is to be expected.

area

type

area

but

were

to contend

playgrounds

London

roadside

of

We have

general

airborne

in concentration, trends.

three

average

investigator

of this

three

results

temporal

Visit

the

same

a 10m

and The

collected.

the

the

not

study.

roadside

distances.

playgrounds

- generally

the

The

for

apart;

increased

of

the

carriageway)

in the

in inner

years

the

magnitude

from

of

(i.e.,

short

of the

each

but

seems

variations.

or long-term

pattern

variation

measurements,

fluctuations

seasonal

There

concentrations.

temporal

A consistent

source

of samples

some

dust-lead of

at

sites.

2.5.

the

type

size

at

dust-lead

short-term any

two

walkway

of site

number

been

of the

the

because

substantial

concentrations

pedestrian

for

dismissing

concentration

in each

types

for

to have

average

The the

to the

appear

different

smaller

as impractical

In contrast does

rather

give study

we

occasions

5000m’.

The

far

shape

as the

and

in a systematic

session,

the

number

sampling

area

of samples

7:

in dust

in a school

concentration sd

playground.

&g

V

R

range

First

44

760

750

110-4950

0.99

45

Second

44

730

440

110-1700

0.60

15

Third

25

700

360

280-1700

0.51

6

It can between

be seen the

three

that means.

although In fact,

V and given

R are

large,

there

is no significant

difference

the

large

values

of

deviation

the

standard

the

three

means

significant during

the

that

the

not

prevent

closer

with

three

than

time

month

sharp

necessary more

seem

change

might

in the

period

lead

of the

in concentration

a representative

figure

to take

a very

large

for

One

was,

conclusion

may

be drawn

short

distances

area

being

obtained.

- a valid

small

It

result

number

playgrounds

that

over

of samples

no

the

quite

occur

a comparatively

then,

from

which the

number

by taking

There in dust

study.

variations

economically

be expected. concentration

is not

can

is do

even

be obtained

of large-area

samples.

CONCLUSIONS

The

concentrations

considerably

over

Our

limited

showing

rather

similar

location,

any

sampling

of

of

in dust

a range lead

a month

can

vary

For

dust

the

lead

may

give

by the

of a week

of either

of 3. and

or two

shown

at a frequency

samples

and

areas

variations

collected

airborne

than

in urban

time.

temporal

samples

of 0.3

less

lead

10 consecutive

of both

period

and

periods

short-terms

in dust

variation

concentrations

short

the

and

- a group of

lead

and

that

in air

a coefficient

representative

airborne

suggest

of lead

are

both

distances

data

concentrations or two

of short

typically

determination

of

at a roadside seriously

misleading

results.

The metres)

variation

quite

practicable

given

location

One Pollution young

of

by taking

the

was

airborne

lead

concentrations

a reliable

and

should

do not

by the be the

this

reinforces

normally

preclude

of

Royal

most

short

distances

variation the

(i.e.,

in airborne

dust-lead

a few

lead,

concentration

be considered

but

of

view

that

often

of

surface assessment

occur

to many

as well

as

of environmental

in the

representative

lead

dust

concentration

of

data.

ACKNOWLEDGEMENTS

The Council,

author Mr

it is

in a

on Environmental

pathway

in the

which

obtaining

Commission

important the

variations the

the

estimate

may

temporal

over

than

samples.

reached dust

[12]

and

more

large-area

‘I...

. ..‘I

spatial

in dust

in dust

conclusions that

material The

lead

to be considerably to obtain

children

lead.

of

is likely

thanks

the

Head

R T Kelly,

for

permission

of Scientific to publish

Services

of

this

paper

the and

Greater

London

his colleagues

for

48 comments.

The

views

the Greater

London

expressed

are

those

of the

author

and not

necessarily

those

of

Council.

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U.S. Environmental ambient air quality 5 October (1978).

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Motto, H. L., Dairies, R. H.; and Motto, C. K.: Lead in soils and plants: relationship to traffic volume and proximity to highways. Environ. Sci. Technol. 4: 231-237 (1970).

5.

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its and

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in the