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Air quality measurements in the Netherlands 2021

RIVM Annual report

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Authors
Affiliation

Pleuni Bongers

National Institute for Public Health and the Environment (RIVM)

Dennis Mooibroek

Published

December 19, 2025

1 Air quality monitoring network in the Netherlands

Air quality in the Netherlands is monitored by the National Air Quality Monitoring Network (LML), which is administered by the National Institute for Public Health and the Environment (RIVM) in collaboration with its regional partners. The resulting data provide a detailed picture of air quality and the concentrations of the various pollutants at the monitoring stations.

This annual report gives an overview of the key measurement values for specific pollutants in 2021 from measurements by RIVM and two of its regional partners DCMR Environmental Protection Agency (DCMR) and The Public Health Service of Amsterdam (GGD Amsterdam). Measurements are carried out under EN ISO/IEC 17025:2017 accreditation by RIVM under L224 in collaboration with its regional partners DCMR (L520) and GGD Amsterdam (L426) who are accredited according to the same ISO standard. Analysis of heavy metals is outsourced to an external analytical laboratory that is accredited according to EN ISO/IEC 17025:2017 under L026. See Appendix A for an overview of all the accreditation certificate numbers for the measurements in this report. Appendix A also includes an overview of ambient air quality limit values. Besides the current limit values from the 2008/50/EC and 2004/107/EC directives, this report will take into account the revised EU directive (2024/2881) on ambient air quality and cleaner air for Europe and, in some occasions, the Air Quality Guideline (AQG) levels from the World Health Organisation (WHO) reported in 2021.

The air quality monitoring sites have specific encoding for EU reporting, where all sites in the Netherlands start with NL, followed by 10 for RIVM sites (L224), 01 for DCMR measurement sites (L520) and 49 for sites from GGD Amsterdam (L426). The remaining 3 numbers denote the unique monitoring site. When hovering over the site codes in this report’s tables, the Dutch site name and location along with the responsible monitoring network will show up. For more information on the monitoring sites (including coordinates), monitoring instruments, and sampling practices, please consult the metadata on the LML data catalog on the public RIVM website. For additional information including measurement uncertainties, see the accompanying README.

2 Key concentration values per component

The upcoming tables contain the key statistics per component for 2021, where mean is the yearly averaged concentration - based on either hourly or daily (24-h) values, P50 and P98 denote the 50th and 98th percentile, max is the maximum measured concentration value, n is the number of valid data points in hours or days, % is the percentage of valid data, max.roll.24 denotes the maximum value of the rolling 24-h mean and max.roll.8 of the 8-h mean. All of these values are in µg/m³ unless otherwise specified and with the exception of values for lead, arsenic, cadmium, nickel and benzo(a)pyrene, which are in ng/m3. Columns that are colored in red indicate an exceedance of the EU limit values from 2008/50/EC or 2004/107/EC, orange represents an exceedance of the revised EU limit values from EU Directive 2024/2881. For several pollutants, additional columns have been added relating to component-specific target values. The summary tables where the annual means have been grouped by site type, only contain yearly averages where data capture meets EU requirements.

Most numbers in this report have been rounded to one decimal place and where deemed logical, to 0 or 2 decimal places. However, for testing against the limit values, the rounding practices of the limit values in the relevant EU Directives have been taken into account, of which most are a whole number. Key statistics rounded to more decimal places than in this report are available on the RIVM public data catalog for air quality measurements, as well as the underlying hourly and daily data.

For some pollutants, relevant statistics are also plotted on an interactive map to provide a quick overview of the concentration distribution throughout the Netherlands and compliance with limit values, and to view specific stations more easily. Every dot represents an individual station and clicking on it will bring up a pop-up with the site code and name, the responsible network, the site type, the component, and the relevant value for that component. Please note that the colors do not necessarily match the colors in the tables of the key statistics. Instead, where possible, the same color categories have been used as the European Environment Agency (EEA) applies in their maps for easier comparison with European data. Only stations with at least 85% of valid data have been included in the maps.

2.1 Nitrogen dioxide

Key statistics for NO2 in 2021
mean1 P50 P98 max median n % exc_2002 max.roll.24 max.roll.8
Rural Background

NL01497

 20.8 15.9 58.5 76.3 15.9 496 5.7 0 51.1 59.8

NL10107

 12.6 10.6 35.1 60.1 10.6 8733 99.7 0 42.5 52.0

NL10131

 12.7 10.3 37.0 67.6 10.3 8722 99.6 0 42.7 46.7

NL10133

 10.1 7.9 29.4 51.9 7.9 8623 98.4 0 36.6 40.2

NL10230

 14.8 10.6 50.3 355.1 10.6 8694 99.2 12 92.8 211.1

NL10235

 13.8 11.1 40.6 98.1 11.1 8736 99.7 0 44.0 55.9

NL10246

 13.9 11.1 43.3 86.9 11.1 8747 99.9 0 46.8 64.8

NL10301

 11.7 8.9 41.7 82.6 8.9 8660 98.9 0 52.5 63.0

NL10318

 12.6 9.4 42.3 106.6 9.4 8693 99.2 0 56.7 92.9

NL10437

 14.7 11.6 45.6 104.5 11.6 8680 99.1 0 57.5 81.2

NL10444

 11.4 8.4 40.4 73.7 8.4 8640 98.6 0 44.5 52.0

NL10538

 10.6 6.2 42.5 195.3 6.2 8571 97.8 0 45.6 81.9

NL10617

 9.5 7.3 34.1 54.1 7.3 8643 98.7 0 41.5 45.8

NL10633

 11.5 8.9 35.5 66.6 8.9 8680 99.1 0 45.5 49.8

NL10644

 13.0 10.3 38.3 65.6 10.3 8641 98.6 0 41.9 51.3

NL10722

 10.6 8.6 33.1 59.1 8.6 8715 99.5 0 40.5 46.9

NL10738

 10.9 8.7 33.9 59.2 8.7 8694 99.2 0 40.6 45.1

NL10807

 8.4 6.5 28.8 44.5 6.5 8728 99.6 0 38.0 42.3

NL10818

 8.2 6.2 28.5 49.1 6.2 8576 97.9 0 35.3 40.6

NL10918

 7.1 4.8 28.4 68.3 4.8 8629 98.5 0 43.1 47.7

NL10929

 7.4 5.8 24.6 48.1 5.8 8516 97.2 0 32.0 36.0

NL10934

 6.0 4.6 22.3 65.1 4.6 8720 99.5 0 32.5 36.0

NL49703

 14.9 10.8 48.3 95.5 10.8 8453 96.5 0 51.8 66.3
Urban Background

NL01485

 21.7 18.3 61.3 133.7 18.3 8506 97.1 0 79.4 117.3

NL01488

 21.1 16.6 65.3 130.9 16.6 8577 97.9 0 87.3 114.0

NL01494

 24.7 20.6 67.2 127.8 20.6 8709 99.4 0 86.3 114.8

NL01495

 24.8 21.2 68.4 150.3 21.2 8739 99.8 0 112.7 143.9

NL01912

 21.8 17.7 62.2 110.9 17.7 8627 98.5 0 71.3 99.2

NL10138

 12.3 9.8 37.7 67.8 9.8 8469 96.7 0 46.6 49.2

NL10241

 17.3 13.6 51.2 103.7 13.6 8648 98.7 0 54.2 70.5

NL10247

 13.4 10.5 40.4 64.4 10.5 8693 99.2 0 52.3 57.8

NL10404

 19.7 14.5 65.3 151.4 14.5 8667 98.9 0 83.5 101.4

NL10418

 23.3 19.3 62.6 119.3 19.3 8740 99.8 0 85.2 113.2

NL10442

 17.3 13.8 51.7 98.5 13.8 8559 97.7 0 47.7 64.3

NL10446

 20.8 16.4 61.3 119.4 16.4 8716 99.5 0 78.2 103.2

NL10643

 15.8 12.4 47.2 88.6 12.4 8553 97.6 0 49.1 62.2

NL10742

 18.0 15.0 49.8 78.6 15.0 8726 99.6 0 56.7 68.6

NL10938

 8.2 6.0 29.5 79.1 6.0 8554 97.6 0 37.9 47.5

NL49003

 16.1 12.7 49.0 115.8 12.7 8715 99.5 0 63.2 82.8

NL49014

 17.4 14.1 48.9 79.5 14.1 8670 99.0 0 48.8 54.8

NL49019

 20.3 16.5 57.0 138.9 16.5 8662 98.9 0 68.1 100.9

NL49021

 14.7 11.7 44.3 97.8 11.7 8717 99.5 0 51.7 68.8

NL49022

 16.3 12.1 51.5 85.1 12.1 8691 99.2 0 58.1 63.4

NL49701

 16.6 11.9 54.0 94.3 11.9 8737 99.7 0 55.5 74.8
Roadside

NL01487

 30.7 27.1 76.6 137.9 27.1 8730 99.7 0 103.8 120.0

NL01489

 26.0 22.9 68.6 117.7 22.9 8733 99.7 0 73.3 91.2

NL01491

 27.6 24.1 68.2 129.5 24.1 8405 95.9 0 91.6 110.1

NL01493

 31.6 28.1 75.6 140.0 28.1 8709 99.4 0 96.8 117.5

NL10136

 19.0 16.4 51.6 101.0 16.4 8463 96.6 0 51.2 69.1

NL10236

 17.8 14.7 48.0 79.0 14.7 8694 99.2 0 50.9 61.9

NL10237

 21.6 18.6 55.0 96.0 18.6 8735 99.7 0 56.0 74.0

NL10240

 22.6 19.4 59.4 101.0 19.4 8595 98.1 0 60.0 72.0

NL10445

 23.8 20.4 66.0 137.8 20.4 8700 99.3 0 84.6 104.4

NL10449

 27.4 23.8 69.0 134.9 23.8 8737 99.7 0 91.3 113.9

NL10550

 18.8 15.7 51.3 111.3 15.7 8546 97.6 0 68.5 71.1

NL10636

 19.2 16.1 53.1 103.3 16.1 8713 99.5 0 59.5 70.8

NL10639

 20.9 17.3 57.7 99.4 17.3 8713 99.5 0 60.7 82.8

NL10641

 20.5 18.2 51.1 84.8 18.2 8653 98.8 0 52.9 61.3

NL10741

 25.5 23.0 59.6 116.3 23.0 8691 99.2 0 65.1 75.7

NL10937

 18.1 16.0 46.5 99.9 16.0 8732 99.7 0 66.7 74.1

NL49002

 32.4 29.3 76.5 158.1 29.3 8734 99.7 0 101.7 119.0

NL49007

 34.0 31.1 79.3 127.9 31.1 8622 98.4 0 100.0 98.9

NL49012

 25.9 21.9 68.5 153.2 21.9 8737 99.7 0 91.1 122.0

NL49017

 24.4 21.0 62.2 104.1 21.0 8639 98.6 0 69.2 82.3

NL49020

 28.3 24.9 69.6 115.0 24.9 8612 98.3 0 74.0 86.3
Industrial

NL01496

 23.9 20.4 76.6 161.2 20.4 8723 99.6 0 111.7 142.2

NL01913

 17.9 14.7 52.9 110.2 14.7 8635 98.6 0 65.2 91.5

NL49704

 20.6 15.5 62.5 132.6 15.5 8573 97.9 0 76.5 95.8
* Hovering over the station code will show the site name, location and responsible monitoring network
Rows where the text is greyed out indicates a data capture < 85%
1 Orange color indicates exceedance of the future EU limit value from 01-01-2030 (2024/2881/EC)
and red of the current EU limit value (2008/50/EC)
2 Number of hours where concentrations exceed 200 µg/m³
- Color indicates exceedance of > 3 times (orange) or > 18 times (red) per calendar year
Table 1: Key concentration values for nitrogen dioxide in 2021 (in μg/m3)
Annual NO2 means per station type in 2021
type mean n
Rural Background 11.2 22
Urban Background 18.2 21
Roadside 24.6 21
Industrial 20.8 3
Table 2: Summary table for nitrogen dioxide in 2021 (in μg/m3)

2.2 Particulate matter

Key statistics for PM10 in 2021
mean1 P50 P98 max median n % exc_50_d2
Rural Background

NL01497

 16.8 16.2 27.9 32.9 16.2 31 8.5 0

NL10131

 17.5 15.1 43.4 82.6 15.1 364 99.7 4

NL10133

 14.9 13.1 31.7 58.5 13.2 362 99.2 2

NL10230

 16.7 14.4 39.6 64.3 14.4 360 98.6 2

NL10235

 15.5 13.9 32.8 54.8 13.9 365 100.0 1

NL10246

 15.3 13.3 34.7 55.1 13.3 365 100.0 1

NL10318

 15.9 14.0 38.1 52.7 14.0 360 98.6 1

NL10437

 15.3 13.8 34.4 57.9 13.8 363 99.5 1

NL10444

 15.0 13.8 34.1 92.7 13.8 360 98.6 1

NL10538

 13.0 12.0 28.6 41.8 12.0 352 96.4 0

NL10617

 14.5 12.8 37.7 53.9 12.8 359 98.4 1

NL10633

 13.7 11.8 33.1 57.8 11.8 359 98.4 1

NL10644

 14.4 12.8 31.4 45.4 12.8 357 97.8 0

NL10722

 14.6 13.6 37.2 50.8 13.6 365 100.0 1

NL10738

 17.4 15.2 42.8 82.6 15.2 363 99.5 4

NL10807

 15.0 12.9 36.7 70.4 12.9 360 98.6 1

NL10818

 14.7 12.9 37.8 54.6 12.9 361 98.9 1

NL10918

 12.9 11.4 33.6 49.7 11.4 362 99.2 0

NL10929

 12.3 10.8 30.5 49.1 10.8 342 93.7 0

NL10934

 14.2 12.5 33.8 47.8 12.5 362 99.2 0

NL49703

 14.7 13.2 34.1 105.4 13.2 347 95.1 1
Urban Background

NL01485

 18.5 16.9 39.6 57.1 16.9 362 99.2 2

NL01488

 19.4 18.0 41.5 59.5 18.0 363 99.5 3

NL01494

 20.0 18.3 42.3 52.4 18.4 362 99.2 2

NL01495

 17.7 16.0 39.7 82.2 16.0 361 98.9 1

NL01912

 19.4 17.5 40.5 56.6 17.5 365 100.0 2

NL10138

 14.5 12.9 33.2 55.5 12.9 363 99.5 2

NL10241

 16.4 14.3 38.6 60.6 14.3 360 98.6 2

NL10247

 16.7 14.5 41.2 61.2 14.5 365 100.0 2

NL10404

 18.1 16.2 40.1 181.7 16.2 360 98.6 1

NL10418

 19.1 17.6 40.7 53.0 17.6 365 100.0 2

NL10442

 15.9 14.3 34.6 58.0 14.3 365 100.0 2

NL10446

 16.2 14.8 34.3 95.1 14.8 363 99.5 1

NL49014

 15.5 14.0 38.2 73.3 14.0 357 97.8 1

NL49016

 17.3 15.6 37.9 91.4 15.6 350 95.9 1

NL49701

 16.1 14.8 35.7 80.3 14.8 362 99.2 1
Roadside

NL01487

 20.1 18.1 51.0 66.4 18.1 360 98.6 8

NL01489

 19.6 17.9 42.3 58.5 17.9 363 99.5 4

NL01491

 18.4 17.0 39.6 58.6 17.0 361 98.9 1

NL01493

 19.9 18.3 42.7 52.8 18.3 363 99.5 3

NL10136

 17.0 15.2 40.3 62.2 15.2 357 97.8 2

NL10236

 17.1 14.8 40.9 64.3 14.9 360 98.6 3

NL10237

 18.8 16.8 41.8 69.2 16.8 362 99.2 2

NL10240

 18.1 16.3 37.9 67.8 16.3 347 95.1 2

NL10445

 19.0 17.3 39.7 187.4 17.3 362 99.2 1

NL10449

 19.8 17.4 47.3 107.8 17.4 365 100.0 4

NL10550

 18.1 16.2 38.8 129.4 16.2 358 98.1 2

NL10636

 16.0 14.7 36.3 78.8 14.8 362 99.2 1

NL10639

 16.6 14.9 38.4 65.0 14.9 365 100.0 3

NL10641

 14.8 13.5 35.6 51.5 13.5 365 100.0 1

NL10741

 19.5 17.2 49.4 83.2 17.2 360 98.6 7

NL10937

 17.7 15.8 38.0 50.3 15.8 365 100.0 0

NL49007

 17.7 15.8 38.8 99.9 15.8 360 98.6 2

NL49012

 18.7 17.0 38.1 101.5 17.0 362 99.2 3

NL49017

 17.9 16.3 38.8 82.4 16.3 353 96.7 1

NL49020

 18.9 16.9 43.3 97.8 16.9 358 98.1 1
Industrial

NL01496

 19.5 17.7 41.0 84.6 17.7 362 99.2 1

NL01913

 22.0 18.9 51.3 68.3 19.0 360 98.6 9

NL49557

 20.9 18.9 49.3 68.5 18.9 355 97.3 7

NL49704

 15.6 13.6 35.7 93.4 13.6 359 98.4 2
Rows where the text is greyed out indicates a data capture < 85%
1 Orange color indicates exceedance of the future EU limit value from 01-01-2030 (2024/2881/EC)
and red of the current EU limit value (2008/50/EC)
2 Number of days where concentrations exceed 50 µg/m³
- Red color indicates exceedance of > 35 times per calendar year
Table 3: Key concentration values for PM10 in 2021 (in μg/m3)
Annual PM10 means per station type in 2021
type mean n
Rural Background 14.9 20
Urban Background 17.4 15
Roadside 18.2 20
Industrial 19.5 4
Table 4: Summary table for PM10 in 2021 (in μg/m3)
Key statistics for PM2.5 in 2021
mean1 P50 P98 max median n %
Rural Background

NL10131

 10.7 9.4 26.8 40.8 9.4 359 98.4

NL10230

 9.6 7.9 25.8 44.0 7.9 357 97.8

NL10444

 8.5 7.2 25.3 71.1 7.2 355 97.3

NL10538

 7.3 5.9 23.6 31.6 5.9 352 96.4

NL10644

 8.1 6.8 24.2 31.4 6.8 350 95.9

NL10738

 9.8 8.1 26.8 67.6 8.1 361 98.9

NL10934

 6.5 5.0 21.1 30.7 5.0 360 98.6

NL49703

 8.8 7.1 25.3 96.2 7.2 352 96.4
Urban Background

NL01485

 10.3 8.8 26.7 40.3 8.8 365 100.0

NL01488

 10.8 9.3 29.5 44.2 9.3 357 97.8

NL01494

 11.6 9.9 30.6 46.3 9.9 362 99.2

NL01495

 10.8 9.1 28.6 44.3 9.1 358 98.1

NL01912

 11.8 10.2 31.0 47.8 10.2 345 94.5

NL10138

 7.7 6.8 21.5 27.7 6.8 358 98.1

NL10241

 7.7 5.7 23.8 40.6 5.8 342 93.7

NL10247

 11.3 10.2 28.7 41.9 10.2 362 99.2

NL10404

 6.7 5.1 25.5 28.8 5.1 348 95.3

NL10418

 8.4 7.2 23.0 34.2 7.2 359 98.4

NL10643

 10.9 9.4 27.5 50.1 9.4 360 98.6

NL10742

 10.8 9.3 26.9 58.6 9.3 359 98.4

NL10821

 7.8 6.5 22.9 52.5 6.5 356 97.5

NL10938

 7.7 6.3 24.7 29.1 6.3 363 99.5

NL49014

 9.8 8.0 27.1 68.7 8.0 358 98.1

NL49016

 9.8 8.4 27.1 83.8 8.4 360 98.6

NL49701

 10.2 8.6 25.2 78.2 8.6 351 96.2
Roadside

NL01487

 11.8 10.1 30.9 64.5 10.1 344 94.2

NL01489

 10.1 8.6 26.8 41.3 8.6 363 99.5

NL01491

 10.2 8.6 27.0 52.8 8.6 361 98.9

NL10136

 8.8 7.4 24.9 30.6 7.4 349 95.6

NL10240

 11.1 9.2 28.7 55.1 9.2 352 96.4

NL10448

 9.6 8.4 26.8 33.5 8.4 363 99.5

NL10449

 9.5 8.2 26.4 52.8 8.2 362 99.2

NL10636

 10.8 9.5 28.3 60.1 9.6 362 99.2

NL10641

 8.8 7.1 25.6 41.6 7.1 362 99.2

NL10741

 10.0 8.3 28.1 57.8 8.3 360 98.6

NL10937

 7.2 5.9 23.5 29.5 5.9 360 98.6

NL49007

 10.2 8.9 27.7 84.5 8.9 361 98.9

NL49012

 10.9 9.2 29.2 93.3 9.2 363 99.5

NL49017

 11.4 9.8 28.3 77.8 9.8 361 98.9
Industrial

NL01496

 9.7 7.8 27.6 35.6 7.9 362 99.2

NL01913

 12.5 10.3 31.9 50.6 10.3 360 98.6

NL49557

 11.2 9.3 32.9 45.4 9.3 357 97.8

NL49704

 10.2 8.4 28.2 83.6 8.5 362 99.2
Rows where the text is greyed out indicates a data capture < 85%
1 Orange color indicates exceedance of the future EU limit value from 01-01-2030 (2024/2881/EC)
and red of the current EU limit value (2008/50/EC)
Table 5: Key concentration values for PM2.5 in 2021 (in μg/m3)
Annual PM2.5 means per station type in 2021
type mean n
Rural Background 8.7 8
Urban Background 9.7 17
Roadside 10.0 14
Industrial 10.9 4
Table 6: Summary table for PM2.5 in 2021 (in μg/m3)
Statistics to determine the AEI for PM2.5
2019 2020 2021 average_3y
Urban Background

NL01494

 12.8 9.7 11.6 11.4

NL10138

 8.5 7.2 7.7 7.8

NL10241

 9.1 7.6 7.7 8.1

NL10247

 11.9 9.9 11.3 11.0

NL10404

 8.6 7.1 6.7 7.5

NL10418

 9.5 8.4 8.4 8.8

NL10643

 10.5 9.0 10.9 10.1

NL10742

 10.6 9.8 10.8 10.4

NL10821

 8.9 7.6 7.8 8.1

NL10938

 8.5 6.9 7.7 7.7

NL49014

 10.4 9.6 9.8 9.9

NL49701

 11.2 9.9 10.2 10.4
* A hyphen is used in case of insufficient valid data to provide an annual mean
Table 7: Annual means for PM2.5 (in μg/m3) on selected urban background sites and the 3-year average to determine the Average Exposure Indicator (AEI)

The Average Exposure Indicator (AEI) for PM2.5 assesses the general population’s long-term exposure to fine particles in urban areas and is based on a 3-year average measured at urban background stations. The AEI in year 2021 is 9.3 µg/m³.

2.3 Sulphur dioxide

Key statistics for SO2 in 2021
mean1 P50 P98 max median n % exc_350_h2 max.roll.24 max.roll.8 exc_125_d3 mean_winter4
Rural Background

NL10133

 0.4 0.2 3.0 11.7 0.2 8489 96.9 0 3.4 5.7 0 0.3

NL10318

 0.7 0.4 4.3 23.0 0.4 8686 99.2 0 5.3 11.0 0 0.6

NL10444

 0.6 0.3 3.6 15.1 0.3 8557 97.7 0 4.8 7.4 0 0.6

NL10644

 0.5 0.3 2.5 24.9 0.3 8599 98.2 0 2.7 5.2 0 0.5

NL10722

 0.4 0.2 3.6 21.0 0.2 8678 99.1 0 8.1 11.1 0 0.5

NL10934

 0.2 0.1 1.2 8.8 0.1 8668 99.0 0 2.1 3.8 0 0.2
Urban Background

NL01485

 1.9 1.0 12.2 78.1 1.0 8718 99.5 0 16.7 23.7 0 1.8

NL01495

 0.8 0.5 5.4 98.3 0.5 8738 99.7 0 11.4 29.5 0 0.8

NL49016

 1.3 1.2 3.7 21.8 1.2 8704 99.4 0 5.0 10.8 0 1.1
Industrial

NL01484

 4.6 2.1 26.2 344.6 2.1 8339 95.2 0 107.2 194.1 0 5.2

NL01496

 1.0 0.6 5.6 44.3 0.6 8721 99.6 0 18.0 29.9 0 1.2

NL49704

 1.0 0.7 4.2 32.0 0.7 8628 98.5 0 6.3 14.3 0 1.0
Rows where the text is greyed out indicates a data capture < 85%
1 Orange color indicates exceedance of the yearly limit value of 20 µg/m³ (2024/2881/EC)
2 Number of hours where concentrations exceed 350 µg/m³
- Color indicates exceedance of > 3 times (orange) or > 24 times (red) per calendar year
3 Number of days where concentrations exceed 125 µg/m³
- Red color indicates exceedance of > 3 times per calendar year
4 Mean concentrations in winter (1 October 2021 to 31 March 2022)
for assessing the critical level for the protection of vegetation and natural ecosystems
- Red color indicates exceedance of 20 µg/m³
Table 8: Key concentration values for sulphur dioxide in 2021 (in μg/m3)
Annual SO2 means per station type in 2021
type mean n
Rural Background 0.5 6
Urban Background 1.4 3
Industrial 2.2 3
Table 9: Summary table for sulphur dioxide in 2021 (in μg/m3)

2.4 Ozone

For ozone, there is no limit value based on the annual mean, instead the number of days where the maximum daily rolling 8-h mean of ozone concentrations exceed 120 µg/m³ is assessed. For the long-term objective, this may not be exceeded on any day. The target value for the protection of human health takes into account data that is averaged over three years. Until 1 January 2030, 120 µg/m³ may not be exceeded on more than 25 days per calendar year averaged over three years and thereafter, it’s set to a maximum of 18 days. See Table 12 for the number of exceedance days in 2019, 2020 and 2021 and their 3-year averages.

In addition, the number of days on which at least one exceedance of the information or alert threshold value is observed, is shown in the columns exc_info and exc_alert in the table below. The information threshold for ozone is 180 µg/m³ for one-hour ozone concentrations and the alert threshold for ozone is 240 µg/m³ for one-hour ozone concentrations.

The ‘Accumulated Ozone exposure over a Threshold of 40 parts per billion’ (AOT40), expressed in (µg/m³) × hours, means the sum of the difference between hourly concentrations greater than 80 µg/m³ (= 40 parts per billion) and 80 µg/m³ over a given period using only the 1-hour values measured between 8:00 and 20:00 Central European Time (CET) each day (EU Directive 2024/2881). The target value for AOT40 is 18000 µg/m³ x h averaged over 5 years. Note that the aot40 values in the table are only for the year 2021 and based on measurements from May up to and including July.

Another widely used ozone indicator for health impact assessment recommended by WHO called somo35 is given in the table. This represents the sum of all daily maximum 8 hour moving averages over 35 ppb - equivalent to 70 µg/m³.

Key statistics for O3 in 2021
mean P50 P98 max median n % max.roll.24 max.roll.8 exc_1201 exc_info2 exc_alert3 aot404 somo355
Rural Background

NL10107

 46.6 46.2 106.6 151.4 46.2 8639 98.6 107.3 143.5 10 0 0 9258.4 2906.4

NL10131

 45.3 45.3 100.0 200.7 45.3 8632 98.5 104.1 151.0 9 1 0 7611.6 2334.9

NL10230

 46.7 47.1 102.6 163.0 47.1 8614 98.3 101.5 154.1 6 0 0 7516.0 2522.8

NL10235

 44.7 44.5 99.2 184.4 44.5 8551 97.6 115.7 159.0 6 1 0 6441.9 2172.6

NL10301

 52.8 53.9 95.8 180.7 53.9 8654 98.8 115.6 163.9 8 1 0 5260.1 2205.5

NL10318

 49.5 50.2 97.0 148.6 50.2 8634 98.6 100.6 135.8 6 0 0 5202.4 2177.2

NL10437

 47.9 49.1 95.1 184.0 49.1 8555 97.7 108.4 157.3 6 1 0 5237.6 1987.5

NL10444

 56.4 59.7 102.5 178.2 59.7 8582 98.0 112.5 150.2 10 0 0 8328.3 3617.8

NL10538

 55.1 56.9 95.0 143.6 56.9 8512 97.2 118.8 129.7 3 0 0 5273.4 2374.8

NL10617

 50.8 51.2 98.2 165.2 51.2 8599 98.2 109.1 146.7 5 0 0 6735.3 2363.9

NL10633

 49.2 49.7 99.5 171.8 49.7 8606 98.2 107.3 149.3 8 0 0 6695.2 2418.2

NL10644

 47.6 47.8 101.3 178.4 47.8 8570 97.8 112.9 155.1 7 0 0 7579.2 2451.5

NL10722

 43.7 42.4 101.2 165.3 42.4 8642 98.7 107.6 142.8 7 0 0 6754.2 2143.2

NL10738

 48.8 49.4 105.3 181.9 49.4 8639 98.6 118.5 157.6 9 1 0 9147.8 2968.5

NL10807

 47.7 47.4 101.4 165.6 47.4 8632 98.5 114.2 148.8 8 0 0 7863.0 2422.3

NL10818

 51.5 51.4 96.8 160.7 51.4 8616 98.4 120.6 144.6 9 0 0 6686.1 2319.3

NL10918

 54.6 55.5 93.8 159.6 55.5 8533 97.4 113.5 137.0 6 0 0 5698.0 2296.0

NL10929

 50.3 49.7 100.5 174.2 49.7 8517 97.2 115.1 162.3 9 0 0 7639.4 2622.4

NL10934

 56.8 57.8 97.7 154.8 57.8 8421 96.1 120.7 144.4 3 0 0 6545.8 2902.4
Suburban Background

NL10133

 45.1 45.4 102.3 158.7 45.4 8519 97.2 94.5 144.9 3 0 0 7044.2 2290.4

NL10247

 48.6 48.8 108.3 170.0 48.8 8604 98.2 105.5 146.2 10 0 0 9033.2 3111.8

NL10938

 51.9 52.6 94.4 170.7 52.6 8632 98.5 119.2 151.6 5 0 0 4997.3 2167.3
Urban Background

NL01485

 43.8 44.5 90.8 181.2 44.5 8710 99.4 114.3 157.4 5 1 0 3880.0 1468.5

NL01494

 41.2 42.0 88.9 154.2 42.0 8745 99.8 106.5 142.9 3 0 0 3201.3 1281.6

NL01495

 44.2 43.8 92.5 153.8 43.8 8748 99.9 101.8 133.5 5 0 0 3879.7 1719.3

NL10138

 49.4 50.6 107.5 158.4 50.6 8623 98.4 107.0 153.2 6 0 0 9126.5 3036.4

NL10241

 46.6 46.9 103.0 177.6 46.9 8632 98.5 118.3 162.2 7 0 0 6923.0 2504.0

NL10404

 52.6 55.6 97.9 160.0 55.6 8586 98.0 107.5 145.8 9 0 0 5499.6 2812.3

NL10418

 46.1 47.2 97.4 173.6 47.2 8644 98.7 122.2 161.5 6 0 0 5447.4 2156.3

NL10442

 49.6 50.8 103.3 174.8 50.8 8636 98.6 119.1 162.1 7 0 0 7419.5 2768.7

NL10446

 47.5 49.9 95.1 159.1 49.9 8618 98.4 112.9 146.5 5 0 0 4948.9 2009.5

NL10643

 46.4 47.1 99.8 164.2 47.1 8649 98.7 108.0 145.3 6 0 0 6422.3 2182.3

NL10742

 47.3 46.9 100.6 178.8 46.9 8617 98.4 114.0 153.6 9 0 0 7337.1 2399.9

NL49003

 49.2 50.7 94.0 148.3 50.7 8713 99.5 105.3 131.5 2 0 0 4598.5 1925.3

NL49014

 49.9 51.4 99.7 156.3 51.4 8634 98.6 109.8 137.1 7 0 0 6237.8 2494.8
Roadside

NL01489

 38.6 38.4 89.4 163.8 38.4 8743 99.8 102.6 148.4 2 0 0 2858.8 1283.5

NL01493

 37.9 38.9 81.9 143.4 38.9 8752 99.9 105.8 130.4 2 0 0 1438.2 748.0

NL10236

 47.1 47.2 101.6 163.0 47.2 8640 98.6 103.6 143.1 9 0 0 6960.3 2344.6

NL10449

 39.9 40.5 88.3 154.7 40.5 8625 98.5 99.5 140.1 3 0 0 3395.3 1127.9

NL10550

 47.9 50.2 90.7 150.3 50.2 8469 96.7 98.0 132.4 2 0 0 3442.7 1543.7

NL10636

 43.9 44.0 96.1 150.5 44.0 8640 98.6 100.1 135.8 3 0 0 4761.5 1824.2

NL10639

 44.4 45.2 94.5 157.2 45.2 8642 98.7 103.0 138.3 4 0 0 4856.6 1794.7

NL10641

 42.9 42.6 91.1 144.1 42.6 8624 98.4 98.6 127.9 4 0 0 4080.4 1433.5

NL49012

 46.1 47.6 90.6 144.6 47.6 8745 99.8 100.4 124.2 2 0 0 3507.2 1431.1
Industrial

NL01496

 48.0 49.2 91.5 151.1 49.2 8741 99.8 97.3 134.4 2 0 0 3316.2 1876.7
Rows where the text is greyed out indicates a data capture < 85%
1 Number of days where the maximum daily rolling 8-h mean of ozone concentrations exceed 120 µg/m³
- Orange color indicates exceedance of > 18 times per calendar year
2 Number of days on which at least one exceedance of the threshold value for information of the public is observed
(one-hour ozone concentration > 180 µg/m³ (information threshold))
3 Number of days on which at least one exceedance of the threshold value for alerting the public is observed
(one-hour ozone concentration > 240 µg/m³ (alert threshold))
4 Accumulated amount of Ozone over the Threshold value of 40 ppb (May - July), related to vegetation [µg/m³ h]
- Blue color indicates exceedance of 18000 [µg/m³ h]
5 Sum of max. 8 hour moving averages > 35 ppb or 70 [µg/m³ d] (WHO)
Table 10: Key concentration values for ozone in 2021 (in μg/m3)
Annual O3 means per station type in 2021
type mean n
Rural Background 49.8 19
Suburban Background 48.5 3
Urban Background 47.2 13
Roadside 43.2 9
Industrial 48.0 1
Table 11: Summary table for ozone in 2021 (in μg/m3)
Number of exceedance days for O3
2019 2020 2021 average_3y1
Rural Background

NL10107

 18 22 10 17

NL10131

 16 20 9 15

NL10230

 20 22 6 16

NL10235

 18 21 6 15

NL10301

 17 18 8 14

NL10437

 13 15 6 11

NL10444

 19 19 10 16

NL10538

 17 11 3 10

NL10617

 15 11 5 10

NL10633

 16 13 8 12

NL10644

 17 16 7 13

NL10722

 23 17 7 16

NL10738

 19 12 9 13

NL10807

 20 12 8 13

NL10918

 15 10 6 10

NL10929

 17 11 9 12

NL10318

 - 15 6 10

NL10818

 - 13 9 11

NL10934

 - 7 3 5
Suburban Background

NL10133

 19 15 3 12

NL10247

 14 26 10 17

NL10938

 16 9 5 10
Urban Background

NL01485

 16 14 5 12

NL01494

 16 10 3 10

NL01495

 16 12 5 11

NL10138

 22 26 6 18

NL10241

 12 20 7 13

NL10404

 13 14 9 12

NL10418

 17 16 6 13

NL10442

 16 21 7 15

NL10446

 17 15 5 12

NL10643

 17 13 6 12

NL10742

 19 16 9 15

NL49003

 16 7 2 8

NL49014

 17 13 7 12
Roadside

NL01489

 13 13 2 9

NL01493

 12 8 2 7

NL10236

 19 17 9 15

NL10550

 15 11 2 9

NL10639

 15 12 4 10

NL10641

 16 8 4 9

NL10449

 - 12 3 8

NL10636

 - 13 3 8

NL49012

 - 6 2 4
Industrial

NL01496

 16 15 2 11
* A hyphen is used in case of insufficient valid data to provide an annual mean
1 Number of days averaged over 3 years where the maximum daily rolling 8-h mean of ozone concentrations exceed 120 µg/m³
- Orange color indicates exceedance of > 18 times per calendar year and red of > 25 times per calendar year
Table 12: Number of days where the maximum daily rolling 8-h mean of ozone concentrations exceed 120 µg/m³ in 2019, 2020 and 2021

2.5 Carbon monoxide

Key statistics for CO in 2021
mean1 P50 P98 max median n % max.roll.24 max.roll.8 exc_100002
Urban Background

NL49014

 336.2 324.4 567.9 1576.6 324.4 8497 97.0 934.5 946.5 0
Roadside

NL49007

 397.2 370.9 748.1 1568.6 370.9 8558 97.7 1220.8 1152.2 0

NL49012

 343.4 314.8 662.8 1412.3 314.9 8724 99.6 980.0 959.0 0
Rows where the text is greyed out indicates a data capture < 85%
1 Orange color indicates exceedance of the future EU limit value from 01-01-2030 (2024/2881/EC)
and red of the current EU limit value (2008/50/EC)
2 Number of days where the maximum daily 8 hour mean concentrations exceed 10000 µg/m³
- Red color indicates an exceedance of at least 1 time per calendar year
Table 13: Key concentration values for carbon monoxide in 2021 (in μg/m3)
Annual CO means per station type in 2021
type mean n
Urban Background 336.2 1
Roadside 370.3 2
Table 14: Summary table for carbon monoxide in 2021 (in μg/m3)

2.6 Black carbon

There currently is no limit value for black carbon as the evidence base is not yet sufficient enough to provide a basis for legally binding limit values (WHO, 2021).

Key statistics for BC in 2021
mean P50 P98 max median n % max.roll.24 max.roll.8
Rural Background

NL01437

 0.6 0.4 2.1 9.1 0.4 8692 99.2 4.2 3.6

NL10131

 0.6 0.5 2.3 9.3 0.5 8708 99.4 7.7 7.7

NL10444

 0.4 0.3 1.9 16.0 0.3 8612 98.3 12.5 13.1

NL10633

 0.5 0.3 1.7 14.6 0.3 8455 96.5 11.7 11.1

NL10644

 0.6 0.4 2.5 8.1 0.4 8621 98.4 7.6 7.0

NL10807

 0.5 0.4 1.6 10.2 0.4 8751 99.9 9.0 9.4

NL10929

 0.4 0.3 1.6 9.2 0.3 8603 98.2 5.9 7.0
Urban Background

NL01488

 0.7 0.5 2.6 12.3 0.5 8717 99.5 11.3 8.6

NL01494

 0.8 0.6 3.0 12.2 0.6 8745 99.8 12.1 7.7

NL10138

 0.7 0.5 2.8 7.3 0.5 8723 99.6 3.2 4.6

NL10247

 0.7 0.5 3.3 8.3 0.5 8599 98.2 7.8 7.2

NL10742

 0.7 0.5 2.6 11.2 0.5 8589 98.0 10.2 10.1

NL10821

 0.6 0.4 2.3 10.8 0.4 8727 99.6 10.8 9.0

NL10938

 0.4 0.3 1.4 21.1 0.3 8468 96.7 11.7 8.7

NL49003

 0.6 0.4 2.3 13.7 0.4 8742 99.8 11.0 11.7

NL49014

 0.6 0.4 2.0 17.2 0.4 8643 98.7 12.1 13.3

NL49701

 0.6 0.4 2.4 12.8 0.4 8753 99.9 11.0 11.5
Roadside

NL01487

 1.2 0.9 4.1 13.7 0.9 8588 98.0 13.2 9.8

NL01491

 0.9 0.7 3.2 13.7 0.7 8382 95.7 12.4 9.4

NL01492

 1.0 0.8 3.1 29.2 0.8 8721 99.6 5.3 5.6

NL01493

 1.3 1.0 4.5 10.7 1.0 8661 98.9 9.8 8.0

NL10237

 1.1 0.9 3.8 11.7 0.9 8747 99.9 8.0 8.7

NL10641

 0.8 0.7 2.5 11.3 0.7 8674 99.0 10.2 10.1

NL10741

 1.1 0.9 3.3 12.2 0.9 8564 97.8 10.5 10.5

NL49007

 1.0 0.8 3.4 15.2 0.8 8658 98.8 10.7 11.4

NL49012

 0.8 0.6 2.6 15.2 0.6 8746 99.8 11.1 11.8

NL49017

 0.9 0.7 2.7 14.3 0.7 8712 99.5 11.0 11.6

NL49020

 1.0 0.8 3.2 15.8 0.8 8754 99.9 12.4 12.6
Industrial

NL01496

 0.7 0.5 2.7 8.8 0.5 8720 99.5 4.4 5.8
Rows where the text is greyed out indicates a data capture < 85%
Table 15: Key concentration values for black carbon in 2021 (in μg/m3)
Annual BC means per station type in 2021
type mean n
Rural Background 0.5 7
Urban Background 0.6 10
Roadside 1.0 11
Industrial 0.7 1
Table 16: Summary table for black carbon in 2021 (in μg/m3)

2.7 Volatile organic compounds

Key statistics for benzene in 2021
mean1 P50 P98 max median n %
Rural Background

NL49703

 0.4 0.2 1.2 2.9 0.2 346 94.8
Urban Background

NL01485

 0.7 0.6 1.8 2.1 0.6 357 97.8

NL01494

 0.9 0.9 2.2 2.9 0.9 361 98.9

NL01495

 1.0 0.8 3.2 8.2 0.8 345 94.5

NL10643

 0.3 0.2 0.8 1.1 0.2 334 91.5
Roadside

NL49017

 0.7 0.6 1.6 3.5 0.6 352 96.4
Industrial

NL01484

 0.6 0.5 2.5 7.4 0.5 359 98.4

NL01496

 0.4 0.3 1.3 5.1 0.3 358 98.1

NL49704

 0.5 0.4 1.7 3.3 0.4 347 95.1
Rows where the text is greyed out indicates a data capture < 85%
1 Orange color indicates exceedance of the future EU limit value from 01-01-2030 (2024/2881/EC)
and red of the current EU limit value (2008/50/EC)
Table 17: Key concentration values for benzene in 2021 (in μg/m3)
Annual benzene means per station type in 2021
type mean n
Rural Background 0.4 1
Urban Background 0.7 4
Roadside 0.7 1
Industrial 0.5 3
Table 18: Summary table for benzene in 2021 (in μg/m3)

For toluene there is no legally binding limit value. Other VOCs are also measured by the LML, but are excluded from this report.

Key statistics for toluene in 2021
mean P50 P98 max median n %
Rural Background

NL49703

 0.9 0.5 4.3 8.4 0.5 346 94.8
Urban Background

NL01485

 2.2 1.9 6.5 9.0 1.9 357 97.8

NL01494

 3.8 3.4 8.9 13.1 3.4 361 98.9

NL01495

 3.7 2.9 12.1 18.9 2.9 345 94.5

NL10643

 0.5 0.4 1.9 2.5 0.4 334 91.5
Roadside

NL49017

 2.0 1.8 4.9 6.3 1.8 352 96.4
Industrial

NL01484

 1.4 1.0 5.2 9.0 1.0 359 98.4

NL01496

 0.6 0.4 1.9 8.8 0.4 358 98.1

NL49704

 1.2 0.6 6.2 9.4 0.6 345 94.5
Rows where the text is greyed out indicates a data capture < 85%
Table 19: Key concentration values for toluene in 2021 (in μg/m3)
Annual toluene means per station type in 2021
type mean n
Rural Background 0.9 1
Urban Background 2.6 4
Roadside 2.0 1
Industrial 1.1 3
Table 20: Summary table for toluene in 2021 (in μg/m3)

2.8 Heavy metals

The measurements of lead, arsenic, cadmium and nickel as shown in the tables below are based on PM2.5 and PM10 filter sampling.

Key statistics for Pb in 2021
mean1 P50 P98 max median n % filter_type
Rural Background

NL10627

 4.0 2.9 17.0 25.2 2.9 174 47.7 PM10

NL10644

 5.3 3.4 12.7 77.8 3.4 86 23.6 PM2.5
Industrial

NL49557

 12.8 8.9 45.0 45.0 8.9 163 44.7 PM10
Rows where the text is greyed out indicates a data capture < 45%
1 Orange color indicates exceedance of the annual EU limit value
Table 21: Key concentration values for lead in 2021 (in ng/m3)
Key statistics for As in 2021
mean1 P50 P98 max median n % filter_type
Rural Background

NL10627

 0.4 0.3 1.9 2.3 0.3 173 47.4 PM10

NL10644

 0.4 0.3 1.3 2.5 0.3 86 23.6 PM2.5
Industrial

NL49557

 0.8 0.4 2.0 2.0 0.4 163 44.7 PM10
Rows where the text is greyed out indicates a data capture < 45%
1 Orange color indicates exceedance of the annual EU limit value
Table 22: Key concentration values for arsenic in 2021 (in ng/m3)
Key statistics for Cd in 2021
mean1 P50 P98 max median n % filter_type
Rural Background

NL10627

 0.1 0.1 0.4 1.1 0.1 180 49.3 PM10

NL10644

 0.1 0.1 0.3 0.6 0.1 80 21.9 PM2.5
Industrial

NL49557

 0.2 0.1 1.4 1.4 0.1 163 44.7 PM10
Rows where the text is greyed out indicates a data capture < 45%
1 Orange color indicates exceedance of the annual EU limit value
Table 23: Key concentration values for cadmium in 2021 (in ng/m3)
Key statistics for Ni in 2021
mean1 P50 P98 max median n % filter_type
Rural Background

NL10627

 0.7 0.6 1.7 2.9 0.6 179 49.0 PM10

NL10644

 0.6 0.5 1.6 2.6 0.5 87 23.8 PM2.5
Industrial

NL49557

 3.0 2.5 13.9 13.9 2.5 163 44.7 PM10
Rows where the text is greyed out indicates a data capture < 45%
1 Orange color indicates exceedance of the annual EU limit value
Table 24: Key concentration values for nickel in 2021 (in ng/m3)

The annual means in the table below are based on solely PM10 filter sampling to conform with EU standards.

Annual heavy metals means per station type in 2021
component mean n
As 0.6 2
Cd 0.2 2
Ni 1.8 2
Pb 8.4 2
Table 25: Summary table for lead, arsenic, cadmium and nickel on PM10 filters in 2021 (in ng/m3)

2.9 Benzo(a)pyrene

Benzo(a)pyrene concentrations based on PM10 filter sampling for 2021 are given in the following table.

Key statistics for benzo(a)pyrene in 2021
mean1 P50 P98 max median n %
Rural Background

NL10444

 0.03 0.01 0.12 0.21 0.01 178 48.8
Urban Background

NL10418

 0.05 0.02 0.25 0.33 0.03 182 49.9
Industrial

NL49557

 0.24 0.11 1.69 2.18 0.11 167 45.8
Rows where the text is greyed out indicates a data capture < 30%
1 Orange color indicates exceedance of the annual EU limit value
Table 26: Key concentration values for benzo(a)pyrene in 2021 (in ng/m3)

3 Discussion

For all annual LML data from 1976 up to the present year, please consult the RIVM Data catalog. The monitoring data over several years including long-term trend charts can be assessed in the section on air quality on the Environmental Data Compendium website (Compendium voor de Leefomgeving). This website also provides information about the health impact of certain pollutants. The burden of disease due to air pollution can be significant, even if concentrations comply with the European limit values. Substantial improvements in public health can be achieved with further reduction of concentrations below the limit values.

4 References

Appendix A - Overview of accreditation information and limit values

The following table lists the accreditation certificate numbers for the LML for the measurements reported here and the limit values in µg/m³ for each pollutant from the three relevant guidelines. Measurements are carried out under EN ISO/IEC 17025:2017 accreditation by RIVM (L224) in collaboration with its regional partners DCMR (L520) and GGD Amsterdam (L426) who are accredited according to the same ISO standard. Analysis of heavy metals is outsourced to an external analytical laboratory that is accredited according to EN ISO/IEC 17025:2017 under L026.

component accreditation_numbera averaging_period EU_limit_value EU_limit_value_revised WHO_AQG
NO2 L520, L224, L426 year 40 20 10
PM10 L520, L224, L426 year 40 20 15
PM10 L520, L224, L426 day 50 max 35×b 45 max 18×b 45 max 3-4×b
PM2.5 L520, L224, L426 year 25 10 5
PM2.5 L520, L224, L426 day
25 max 18×b
O3 L520, L224, L426 max_8_h 120 max 25×b 120 max 18×b,c 100 max 3-4×b
O3 L520, L224, L426 peak_season

60
SO2 L520, L224, L426 day 125 max 3× 50 max 18× 40
SO2 L520, L224, L426 year
20b
CO L426 max_8_h 10000 10000 10000
CO L426 day
4000 max 18×b 4000 max 3-4×b
benzene L520, L426 year 5 3.4 1.7
Pb sampling L224/analysis L026 year 0.5 0.5 0.5
As sampling L224/analysis L026 year 0.006 0.006 0.066
Cd sampling L224/analysis L026 year 0.005 0.005 0.005
Ni sampling L224/analysis L026 year 0.02 0.02 0.025
benzo(a)pyrene sampling L224/analysis N/A, L426 year 0.001 0.001 0.12
a L224 is RIVM, L520 is DCMR, L426 is GGD Amsterdam, L026 is the analytical laboratory of TNO
b max n× means a maximum number of n exceedance days per calendar year
- For WHO this is also denoted as the 99th percentile, which is equivalent to 3-4 exceedance days per year
c Averaged over 3 years
Table 27: Accreditation information and limit values in μg/m3 from EU Directives 2008/50/EC and 2004/107/EC (EU_limit_value),
EU Directive 2024/2881 (EU_limit_value_revised), and WHO global air quality guidelines from 2021 (WHO_AQG)