Proposal for a COUNCIL DECISION establishing a reciprocal exchange of information and data from networke and individual stations measuring ambient air pollution within the Member States
Date: 1994-09-07
Institutions: European Commission
Subjects: air quality, applied research, disclosure of information, exchange of information, pollution control, statistics

COMMISSION  OF THE EUROPEAN  COMMUNITIES 

SÊ&is^R-*>iK'Ji«a 

C0M(94) 345 def. 
Bruxelles,  7.09.1994 

94/0194 (SYN) 

Proposal  for a 

COUNCIL DECISION 

establishing a reciprocal exchange of Information and data fro» 
networfce and individual  stations e*aeurlng aablent air pollution within 
the MeMber  States 

S S S IS 

(presented by the Commission) 

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-  2 -

EXPLANATORY  MEMORANDUM 

Introduction 

The purpose of  this proposal  is to establish  an exchange of  information and 
data  from networks and  individual  stations measuring  ambient  air  pollution 
within  the Member  States. 

It has been drawn up on  the basis of  the fifth European Community  action 
programme on  the environment  (Council  Resolution of  1 February  1993 on  the 
fifth programme  published  in Official  Journal  C  138 of  17 May  1993). 

The  report  on  the state of  the environment  published  at  the same  time as  the 
programme  pointed  out major  shortcomings concerning  the quantity,  quality 
and comparability  of  data on  the environment.  It  is therefore specified  in 
the  fifth programme  that  "bearing  in mind  the relationship between  good 
decisions and good  information,  it  is  imperative  that  under  this programme a 
high  level of  priority  be assigned  to filling  the current  gaps  in baseline 
data on  the environment  and  improving  their  compatibility, comparability  and 
transparency."  The collection of  environmental  information and  data, 
including  air  quality  information  and  data,  is one of  the  responsibilities 
of  the European  Environment  Agency, whose  task  it  is to provide  the 
Community  and  the Member  States w Uh  reliable  Information which  is 
comparable  at  European Community  level. 

The proposal  also  fits  in with Community  policy on  the control  of  air 
pollution;  together  with  the  information supplied  by  the Member  States about 
the  implementation  and  application of  the air  quality  directives, the 
exchange of  information will  provide  a very  important  source of  information 
for  the purpose of  adapting and  developing  policy  in this area. 

The proposed measure  is designed  to  improve and update measures already 
undertaken  by  the Commission,  and  its nature necessitates  the  taking of 
action at Community  level. 

This proposal  has been drawn up  in close cooperation with  the Agency  Task 
Force on  the basis of  the experience of  the exchanges of  informât ion.and 
data established  by Decisions 75/441/EEC and 82/459/EEC.  Its aim  is to 
define  the scope and operating  procedures  for  the new exchange of 
information and data on ambient  air  quality. 

Experience with the exchanges of  Information established by 
Decisions 75/441/EEC and 82/459/EEC 

- 3 -

These exchanges of  information made  it possible to set up a data bank 
containing the results of 13.7 million measurements.  It contains 24-hour 
data for sulphur  compounds, suspended particulates and heavy metals and 
one-hour  data for nitrogen oxides, ozone and carbon monoxide.  The data 
transmitted concern a total of 163 towns and cities with over 1 000 
Inhabitants.  A detailed description of the content of the bank is 
available.1  it operates using a specific software system known as APIS 
(Air Pollution  Information System), and a manual  is also available.  The 
system software and all the data have been made available to the 
Member States.  Transfers of data have also been carried out with the COR INE 
programme and with the GEMS (Global  Environment Monitoring System -
WHO/UNEP). 

Generally speaking, experience with  these exchanges of  information has been 
favourable, but many drawbacks and problems have emerged: 

-  the procedure developed has proved to be very cumbersome to manage and 

difficult  to adapt  in terms of design and the technical  means deployed; 

-  the data  transferred concerned only a small  number of pollutants; 
-  the procedure  related to a  limited number of stations selected by the 

Member  States; they were not necessarily  representative; 

-  the different measurement  techniques used  by  the Member  States were not 

necessarily comparable; 

-  the processing of data by the Member  States prior to transfer was not 

harmonized. 

New exchange of  information and data 

Compared with the previous exchanges of  information, this proposal to 
establish a new exchange of  information seeks to extend the scope and 
improve the quality of the data  transmitted while ensuring that the 
procedure to be followed  is flexible.  To this end, various procedures have 
been developed: 

With  regard  to  the  stations 

The proposal  does not require the Member  States to install new measurement 
stations.  A distinction  is made between the stations used for the purpose 
of  Implementing the air quality directives and those not used for this 
purpose.  The stations used for the purposes of the (existing and future) 
air quality directives will  take part  in the new exchange of  information. 

1  In English only. 

- 4 -

Homogeneous  results will  be guaranteed,  to the extent  that  the directives in 
question  lay down  (or will  lay down) station-siting  criteria and the 
measurement  techniques to be used. 
In addition  to those  stations, the Member  States are requested  to select 
additional  stations  principally for pollutants not covered by the air 
quality  directives,  in order  to make an estimate of  local  and/or  regional 
pollution  levels. 

With  regard  to 

pollutants 

The proposal  provides for the transfer of data  concerning 34 pollutants to 
the extent  that  they are measured by the Member  States  (seven are at present 
covered by air quality  directives).  This  list  contains pollutants known to 
present  risks for human  health  and/or  for the environment  in general. 
Provision  is made  for this  list to be revised or extended by a Committee for 
adaptation to technical  and scientific  progress  in the light of new 
knowledge  (toxicology, measurement  techniques, etc.) or new needs. 

With  regard  to  the  data 

transmitted 

The proposai  provides  for the transfer of all the raw data  from at  least 30% 
of the stations used  for the purpose of  implementing air quality  directives 
and  from  stations which  took  part  in the previous exchanges of  information. 
The annual  statistics for concentrations measured at all  the stations  should 
be  transmitted. 
To ensure  that  the data  transmitted are of homogeneous  quality, the proposal 
specifies minimum  criteria  for data  quality  control  and aggregation and for 
calculating  statistical  parameters. 

An extension of the procedure to include non-Community  countries might be 
envisaged on the basis of the opinion of the experts meeting within the 
Committee  provided  for by the Decision. 

With  regard 

to  the  practical 

data-transfer 

procedures 

The proposal  simply  lays down the time  limits for the transfer of data. 
In order  to make the procedure more  flexible and adaptable, the technical 
aspects  (transfer  medium,  data  formatting, technical  means, etc.) will be 
determined by the Committee set up by Oirective 94/.../EEC on ambient air 
quality assessment  and management on the basis of a Commission  proposal  In 
line with  ISO standard 7168. 

- 5 -

With regard  to  liaison  with  Commission  and EEA activities 
emissions Inventory 

concerning  the 

Apart  from the tasks already mentioned  (revision of the list of pollutants 
and'technical  transfer  procedures), the Committee for adaptation to 
technical and scientific progress will also be responsible for ensuring 
liaison with activities concerning the emissions  inventory  (CORINAIR). 

Value of a new exchange of  Information and data 

The new exchange of  information and data will make  it possible: 

-  to obtain an overview of air pollution at local, regional, national and 

Community  level  (present  situation and trend); 

-  to identify potential problems and provide a basis for preparing 

preventive measures; 

-  to estimate the impact of the Commission's environment  policy with  regard 

to air qua Iity; 

-  to initiate and stimulate scientific work and research such as modelling 
the transport of pollutants and the formation of secondary  pollutants, 
and the correlation between emissions and epidemiological  surveys; 

-  to circulate  information both within end outside the Community; and 

-  to supply  international organizations which cover a wider  geographical 

area (e.g. OECD, UNEP, WHO) with a set of homogeneous data validated for 
the Community, and in so doing  reduce the Member  States' workload. 

Proposal 

for  a 

r r ^ K i rn  DECISION 

establishing  a  reciprocal  exchange  of 

Information  and  data 

from 

networks  and  individual  stations  measuring  ambient  a ir  p o l l u t i on  w i t h in 
the  Member  States 

The Council of the The European Union; 

Having regard to the Treaty establishing the European Community and in particular Article 130 s, 
paragraph 1, thereof; 

Having regard to the proposal from the Commission , 

In cooperation with  the European Parliament 

Having regard to the opinion of the Economic and Social Committee . 

Whereas the fifth  European Community action programme on  the environment 
provides  for  the collection of baseline data'on the environment  and an 
improvement  in their  compatibility, comparability and  transparency; 

Whereas the objectives and  tasks of  the European Environment Agency  are set 
out  in Council  Regulation  (EEC) No 1210/90; 

Whereas  it  is necessary  to establish a procedure for the exchange of 
information on air quality  in order  to combat pollution and nuisance, this 
being one of  the Community's objectives concerning  the  improvement of the 
quality of  life and  the harmonious development of economic activities 
throughout  the Community; 

Whereas the experience built up as the result of  the exchanges of 
information established by Decisions 75/441/EEC and 82/459/EEC makes it 
^possible to establish a more complete and more representative exchange of 

information by  increasing  the number of pollutants and stations considered; 

Whereas using common criteria for validating and processing  the measurement 
results will  increase the compatibility and comparability of  the data 
transmitted; 

Whereas the  information collected needs to be sufficiently  representative to 
enable pollution  levels to be mapped  throughout  the Community; 

Whereas exchanging  the results of measurements of pollution  levels will make 
it possible  to monitor  long-term  trends and  improvements resulting from 
national  and Community  legislation to combat air pollution; 

Whereas air-quality  data need  to be transmitted  for the purposes of  certain 
international programmes, 

HAS ADOPTED THIS  DECISION: 

- 7  -

Article 1 

A reciprocal  exchange of  information and  data  from networks and  individual 
stations measuring  ambient  air pollution, hereinafter  referred  to as 
"reciprocal  exchange",  is hereby established,  it shall  apply  to: 

-  networks and  stations, covering  detailed  Information  describing  the 
air-pollution monitoring networks and stations operating  in the 
Member  States, and 

-  measurement  results, covering  statistics and  individual  results obtained 
from  the measurement  of air  pollution  by stations  in the Member  States. 

The Commission  will  be responsible  for  the operation of  the  reciprocal 
exchange;  it will  call  upon  the European  Environment  Agency  for  matters 
falling within  the  latter's sphere of  competence. 

The  reciprocal  exchange  shall  cover  the pollutants  listed  in Annex  1 to the 
extent  that  they  are measured  in the Member  States. 

Article  2 

Article  3 

The following  stations shall  take part  in the reciprocal  exchange: 

(a) 

(b) 

(c) 

all  stations used  for  the purpose of  implementing  the air  quality 
standards directives; 

additional  stations selected  by  the Member  States  in order  to 
estimate  local  pollution  levels for pollutants  listed  in Annex  1 but 
not  covered  by  the air  quality  standards directives ; 

additional  stations selected  by  the Member  States  in order  to make a 
representative estimate of  regional  pollution  levels for all  the 
pollutants  listed  in Annex  1; 

(d) 

where possible,  the stations which  took part  in the reciprocal 
exchange of  information established by Decision 82/4S9/EEC. 

-  8 -

Article  4 

Networks and  stations 

1.-The  information  to be communicated  to the Commission  shall  concern  the 
characteristics of  the measurement  stations,  the measurement  equipment 
and  the operational  procedures  followed  in those stations and  the 
structure  and organization of  the networks  to which  they belong.  The 
information required  is specified  in Annex  2. 

2. The Commission  will  make available  to the Member  States computer  files 
containing  the  information  already  collected  by  its departments on the 
subject  and software enabling  them  to be used  and  updated. 

3. The Member  States  shall  correct/amend  and/or  supplement  that 

information.  The updated  computer  files shall  be sent  to the  Commission 
each  year  by  1 October  at  the  latest;  the first  sending  shall  take place 
by  1 October  1994. 

4. The  technical  procedures  for  the transfer  of  information  shall  be 

specified  in a detailed  technical  note drawn up by  the Committee  referred 
to  in Article  8. 

5. The Commission  shall  include  the  information  transmitted  in  its data 

base. 

6. The Commission  shall  prepare each year  a technical  report  on  the 

Information  collected  and shall  make  available  to the Member  States the 
updated  "networks-stations" data base. 

Article  5 

Measurement  results 

1. The following  results shall  be transmitted  to the  Commission: 

(a) 

(b) 

raw data  and statistics corresponding  to the recommended  averaging 
times  indicated  in Annex  1 for at  least  30% of  the stations referred 
to  in Article  3(a);  those stations must  be distributed  over .the 
entire national  territory, 
raw data  and  statistics corresponding  to the recommended  averaging 
times  indicated  in Annex  1 for all  the stations  referred  to In 
Article 3(d); 

-  9  -

(c) 

at  least  the statistics  indicated  in Annex  1 for  all  the other 
stattone referred to  in Article  3 but  not mentioned  above. 

The  results  sh: N  be expressed  In accordance  with  Annex  1. 

2. The  U, 

zr  strtei 

, iI be  responsible  for  validating  the  raw  date 

-:-'  gonial  rules  set  out  in Annex  3.  Any  aggregation  of 

tran^.jttcd  or  r-t  xo calculate  the  statistical  values  transmitted  in 
ct'r:'/:''ncs  \-'*\' 
for clLia er«d ''.  •-: irui.it Jon of  statistics  by  a Member  Steto  chcll  comply 
t-K.. crltc. i. 
luact  ss stringent  as  those  indicated  in Ar.nox 4.  A 
quality  coc&,  as  set  out  in Annex  5, shall  b®  assigned  t© Gcich  item ©f 
data. 

3. The Membci  States  shall  transmit  the  results  for  the  calendar  year  by 

1 October  of  the  following  year  at  the  latest;  the  first  transfer  shall 
cover  the calendar  year  1992. 

4. The  technical  procedures  for  the  transfer  of  results  shall  be  laid  down 
in a detailed  technical  note  drawn  up  by  the Committee  referred  to  in 
Article  8. 

5. The Commission  shall  include  the data  transmitted  in  its data  base. 

6.  The Cosimission shall  prepare  each  year  a  technical  report  on  the  results 

collected  and  shall  make  available  to  the Member  States  the  updated 
"results"  data  base. 

7.  in agreement  with  the Member  States,  the Commission  shall  ensure  the 

transfer  to  international  bodies of  selected  data  needed  for  the  purposes 
of  various  international  programmes. 

Article  6 

The  information  and  results  transmitted  in the context  of  the  reciprocal 
exchange  shall  be  regarded  as being  accurate unless  they  are  explicitly 
designated  by  the Member  States  as being  temporary  and/or  not  verified.  In 
that  event,  the Member  States  shall  endeavour  to  transmit  the  validated 
results as quickly  as  possible. 

-  10 -

Article  7 

Each Member  State shall  designate a central  body  responsible  for  the 
implementation and operation of  the reciprocal  exchange and shall  forthwith 
inform the Commission  thereof. 

Article  8 

This Decision shall  be adapted  to scientific and  technical  progress via the 
Committee set up by Directive 94/.../EEC on ambient  air  quality  assessment 
and management,  in accordance with Article  12 of that Directive.  Such 
adaptation shall  concern: 

-  the preparation  and updating of detailed  technical  notes concerning  the 

transfer  of data and  information; 

-  the use of new technical  means  for  the transfer  of data and  information; 

-  liaison with  the activities undertaken by the Commission  and the European 

Environment  Agency  concerning  the emissions  inventory; 

-  amendments  to the  list of pollutants given  in Annex  1; 

-  the  incorporation of new concepts of measurement  techniques  in the 

reciprocal  exchange procedure; 

-  the extension of  the procedure  to data and  information from non-Community 

countries. 

- 11 -

Article 9 

This Decision shall apply with effect from 1 October 1994. 

This DaeIaion Is addressed to the Member States. 

Article 10 

Done at Brussels, 

For the Council 

The President 

-  12 -

Annex 1 

List of pollutants, recommended  averaging  times, 
statistical  parameters and units of measurement 

POLLUTANT 

1 
2 
3, 

S02 
AF 
SPM 

4, 
5 
6. 
7, 
8. 
9 
10, 
11 
12, 
13. 
14, 
15 
16. 
17, 
18 
19, 
20. 
21 
22 
23, 
24 
25, 
26, 
27, 
28. 
29. 
30. 

PM10 
BS 
03 
N02 
N0X 
CO 
H2S 
Pb 
Hg 
Cd 
Ni 
Cr 
MN 
As 
CS2 
CgHg 
C6H5-CH3 
C6H5.CH-CH2 
CH2-CH-CN 
HCHO 
C2HC13 
C2CI4 
CH2CI2 
BaP 
PAH 
VC 
COV  (NM) 

31 
32, 
33, 
34, 

COV  (T) 
PAN 
N-dep. 
S-dep. 

AVERAGE 
OVER 

EXPRESSED 
AS 

sulphur  dioxide 
strong acidity 
suspended  particulates 

24h 
24h 
24h 

(total) 

S 02 equivalent 

24h 

24h 
24h 
24h 
24h 

suspended part.(< 10/im)  24h 
24h 
black  smoke 
1h 
oxone 
1h 
nitrogen dioxide 
1h 
nitrogen oxides 
1h 
carbon monoxide 
24h 
hydrogen sulphide 
24h 
lead 
24h 
mercury 
cadm i urn 
nickel 
chromium 
manganese 
arsenic 
carbon disu I phi de 
24h 
benzene 
24h 
toluene 
24h 
styrene 
24h 
acrylonitrile 
1h 
formaldehyde 
24h 
trichloroethylene 
24h 
tetrachloroethylene 
24h 
dichioromethane 
benzo(a)pyrene 
24h 
poiyaromatlc hydrocarbons 24h 
24h 
vinyl  chloride 
vol. org. comp. 
24h 
(total  non-methane) 
vol. org. comp.  (total)  24h 
1h 
peroxyacetyl  nitrate 
1 month 
wet  nitrogen deposition 
1 month 
wet  sulphur deposition 

1h 

N 02 equivalent 

N equivalent 
S equivalent 

-  13 -

The statistics, calculated  over  the calendar  year,  to be  transmitted  to the 
Commission  are as follows: 

-  for pollutants 1 to 32: 

-  for pollutants 33 and 34: 

the arithmetic mean,  the median,  the 
percentiles 98  (and 99.9  for pollutants for 
which  the mean  is calculated over  1 hour) 
and  the maximum calculated  from  raw data 
corresponding  to the recommended  averaging 
times  indicated  in the  table above; for 
pollutant  6  (ozone), the statistical 
parameters should  also be calculated  from 
mean values over  8 hours; 

the arithmetic mean, calculated  from  raw 
data corresponding  to the  recommended 
averaging  times  indicated  in the  table 
above. 

The xth percentile should  be calculated  from  the values actually  measured. 
All  the values should  be  listed  in  increasing  order: 

Xi<-X2<«X3<- 

<-xk<- 

<-XN_.J<-XN 

The xth percentile  is the value of  k, calculated  as  follows: 

lc  -  (q * N) 

where q  is equal  to x/100 and N  is the number  of values actually  measured. 
The value of  (q * N) should  be  rounded off  to the nearest  whole  number. 

All  the results should  be expressed  in microg/m3  (at  the following 
conditions of  temperature  and pressure: 293'K and  101.3 kPa) except  for 
pollutants  33 and  34 for which  the results should  be expressed  in 
g/m2.year. 

-  14 -

Annex  2 

Information concerning networks, stations and measurement  techniques 

As much  Information  as possible should be supplied  about  the  following 
points: 

I. Information concerning  networks 

Name 

Abbreviation 

.  Geographical  coverage  (local  industry, town/city, urban area/conurbation, 

county, region, entire country) 

Body  responsible  for network  management 

name 
name of person  responsible 
address 
telephone  and  fax  numbers 
legal  status  (private, semi-public, public) 

Technical  body  responsible  for network  maintenance 

name 
name of person  responsible 
address 
telephone and  fax  numbers 

Time reference basis  (GMT,  local) 

.  General  information  concerning: 

special  protection areas and warning procedures  in the geographical 
area where  the network  is  located 
data-validation procedure 
statistical  processing  carried out 
information circulated/broadcast  (brochures, reports, radio, TV) 
linkage with data bases containing  information about  the network 
other  relevant  information. 

- 

11.  Information concerning stations 

-  15 -

11.1 General  information 

Name 

Reference number  or code 

.  Name of  technical  body  responsible  for  the station  (if different  from 

that  responsible for  the network) 

.  Type of  station  (local, regional, Community  air  quality directives, GEMS, 

OECD, EMEP, other) 

Date when  first operated 

Date when  last operated 

Period of measurement over  the year 

Geographical  coordinates 

.  Attitude 

.  NUTS Level  II I 

.  Pol Iutants measured 

.  Metereological  parameters measured 

.  Prevailing wind direction 

Ratio between distance  from and height of closest  obstacles 

.  Other  relevant  information 

11.2  Spatial  characteristics 

11.2.1  Immediate surroundings  (100 m  radius) 

.  General  description:  up to four of  the following  Indicators: 

wide street with 

large volume of  traffic (in excess of 
10 000 vehicles a day) 

moderate volume of  traffic  (between 2 000 
and 10 000 vehicles a day) 

low volume of  traffic  (less than 2 000 
vehicles a day) 

pedestrian area 

- 16 -

narrow street with 

large volume of traffic (in excess of 10 000 
vehicles a day) 

moderate volume of traffic (between 2 000 
and 10 000 vehicles a day) 

low volume of traffic (less than 2 000 
vehicles a day) 

pedestrian area 

canyon street with 

large volume of traffic (in excess of 10 000 
vehicles a day) 

moderate volume of traffic (between 2 000 
and 10 000 vehicles a day) 

low volume of traffic (less than 2 000 
vehicles a day) 

pedestrian area 

square 

footpath 

facade of buiI ding 

church tower, terrace 

courtyard, school, hospita 

treee 

vast fiat area 

Industrial area 

tunneI 

field, meadow/grassland 

-  17 -

11.2.2  Local  environment  (5km  radius) 

Landscape morphology:  the area around  the station  Is divided  into four 
sectors.  For each  sector  give  the percentage cf  the  following 
morphological  characteristics: 

« 

urban - commercial 

urban -  industrial 

urban - residential 

mixture of  commercial,  industrial  and  residential 

high  industrial  concentration 

moderate  industrial  concentration 

low  industrial  concentration 

commercial 

residential  (detached  dwe11ings) 

port 

airport 

forest/woodland 

park, natural  area 

crop-growing  area 

stock-farming  area 

hills/mountains, valleys 

seaside or  lakeside 

greenhouses 

If  information by sector  is not  available, the area should be described aa a 
whole, giving up  to four of  the abovementloned parameters. 

Total  population of  the area. 

-  18 -

11.2.3  Characterization of  stations  in terms of  traffic 

.  Total  number  of  vehicles per  day 

Distance of monitor  from centre-line of  road 

Average speed of  traffic 

Characteristics of  traffic 

regular  congestion  affecting  at  least  50% of  vehicles using  the road 

normal  road with a speed  limit of 50 km/h without  regular  congestion 

road with  a speed  limit  in excess of 50 km/h but  not  a motorway 

motorway 

Buses and heavy goods vehicles as a percentage of  total  traffic 

Ratio between  the distance  to the centre-line of  the road and  the height 
of office/apartment  blocks 

Type of  road 

road  in open country;  no building or  trees within  100 m  (or so few 
that  the evenness of  the  land  is not  affected); 

road with  buildings at  least  3 m high on both sides;  no gap wider 
than 25 m and at  least 75 m of buildings per  100 m of  road;  the 
ratio between  the height  of  buildings and  the distance  from  them to 
the centre-line of  the road  is 1.5  to 3 on one side and at  least  3 
on  the other; 

special  instance of  the preceding  type of  road, where  the ratio  is 
less than  1.5  for both  sides of  the  road; 

road with buildings at  least  3 m high on one side and  a  ratio 
between height  of buildings and distance  from  the centre-line of  the 
road  less than 3;  no buildings on  the other  side or a ratio well  in 
excess of  3, preferably  in excess of 10; 

basic  road  type - any  road which cannot  be classified  in any of  the 
other  categories. 

• 

< 

III. 

Information concerning measurement  techniques 

-  19 -

Date when pollutant  first measured 

-Date when pollutant  last measured 

Equipment 

name 

analytical  principle 

date when first used 

date when  last used 

Characteristics of sampling 

height  of sampling point 

length of sampling  line 

result-integrating time (for monitors with continuous output) 

sampling  time  (for monitors where  the sample  ie aniaysed  in the 
laboratory or without continuous output) 

Calibration 

type:  automatic, manual, automatic and manual 

method 

frequency 

Zero adjustment 

type: automatic, manual, automatic and manual 

method 

frequency 

Maintenance 

frequency of  maintenance 

frequency of checking of calibration  system. 

-  20 -

Annex  3 

Raw data validation procedure 

The purpose of  the raw data validation procedure  is to filter out  incorrect 
or doubtful  data before  they are transferred  to the final  data base or  to an 
outside user. 

The validation procedure should comprise at  least  the following two stages: 

ths first stage consists  in marking  the data:  they are not corrected or 
rejected  and  remain physically  available.  Evente  to be taken  into 
consideration  in this connection  are, for example:  disturbances due to 
maintenance, calibration or  technical  problems, off-scale measurements, 
and data  indicating  rapid  variations, such as excessive falIs or  rises. 

The data should  also be revised on the basis of criteria based on a 
knowledge of  climatic and meteorological  influencée specific to the site 
during  the measurement  period; 

the purpose of  the second stage, to be carried out subsequently,  is to 
detect erroneous measurements  by techniques such as comparison with 
preceding months and with other  pollutants and standard  deviation 
analysis. 

The validation  list drawn up during  the first stage should also be 
examined  and  verified. 

After  the two stages, erroneous data can be physically  rejected and need not 
be transmitted.  Nevertheless, the reason for rejecting  them should be 
indicated at  the time of  transfer  by means of one of  the quality codes 
indicated  In Annex  5. 

-  21  -

Annex  4 

Criteria  for  the aggregation of  raw data 
and  the calculation of statistical  parameters 

(a) 

Aggregation of  raw data 

The criteria  for  the calculation of one-hour  and 24-hour  values from data 
with a smaller  averaging  time are: 

-  for one-hour  values: 

-  for  24-hour  values: 

at  least 75% of  data accepted  (codes V, 0, R 
defined  in Annex  5) 
over  50% of one-hour  data  accepted  (codes V, 
0, R defined  in Annex  5) and not more  than 
25% of  successive data values not  accepted 
(codes C, Z, M, D, N, T defined  in Annex  5) 

(b) 

Calculation of statistical  parameters 

-  for  the mean and  the median: over  50% of data accepted  (codes V, 0, R 

defined  in Annex  5) 

-  for  the percentiles 98, 
99.9 and the maximum: 

over  75% of data accepted  (codes V, 0, R 
defined  in Annex  5) 

The ratio between  the number  of  valid data  (codes V, 0, R defined  in 
Annex  5) for  the two seasons of  the year  considered  cannot  be greater  than 
2, the two seasons being winter  (from January  to March  inclusive and  from 
October  to December  inclusive) and summer  (from April  to  September 
inclusive). 

-  22  -

Annex  5 

Quality  codes 

(a) 

Raw data quality codes 

These codes characterize the validity and quality of the raw data: 

Data  accepted: 

V 
0 
R 

valid  data 
corrected  data 
reconstructed  data 

Data  rejected: 

C 
Z 
M 
D 
N 

data disturbed by the calibration  procedure 
data disturbed by the zero-adjustment  procedure 
data disturbed by the maintenance  procedures 
erroneous data due to technical  deficiency 
erroneous data for unknown  reason 

Temporary  data: 

T 

data not subjected  to adequate validation  procedures 

(b) 

Aggregated  data quality codes 

These codes characterize  the validity and quality of the aggregated  data 
They are eimiiar to those defined  for raw data.  The code adopted on 
aggregation  is the code assigned  to the most  frequent  raw data. 

Data  accepted: 

V 
0 
R 

valid data 
corrected  data 
reconstructed  data 

-  23 -

C 
Z 
M 
D 
N 

data disturbed by the calibration procedure 
data disturbed by the zero-adjustment procedure 
data disturbed by the maintenance procedures 
erroneous data due to technical deficiency 
erroneous data for unknown reason 

Temporary data: 

T 

data not subjected  to adequate validation procedures 

(c) 

Statistical  data quality codes 

Theee codée characterize the validity and quality of the etatlsticai data: 

Valid data: 

V 

valid data  (number and distribution of raw data V, 0, R  sufficient) 

Data rejected: 

1 

R 

number of raw data V, 0, R insufficient 

insufficient distribution of raw data over the period considered 

Temporary data: 

T 

data calculated on the basis of raw data not subjected to adequate 
validation procedures. 

HT 

ISSN 0254-1475 

COM (94) 345 final 

DOCUMENTS 

EN 

14 

Catalogue number : CB-CO-94-358-EN-C 

ISBN 92-77-72030-1 

Office for Official Publications of the European Communities 
1^2985 Luxembourg