Traffic station – minimum requirements
Traffic station – minimum requirements (EU framework + EEA European Air Quality Index)
Airbox V3 project. Scope: an air quality monitoring station classified as traffic that must
(a) comply with the EU ambient air quality framework and (b) be displayed in full colour on the
EEA European Air Quality Index (https://airindex.eea.europa.eu/AQI/index.html).
Industrial and background stations are covered in a separate document.
Prepared 3 November 2026. Sources are cited inline with these short names:
| Short name | Document |
|---|---|
| Dir. | Directive (EU) 2024/2881, final Council text ST 7135/24 (article / annex numbering as in that text) |
| IPR | Commission Implementing Decision 2011/850/EU (e-reporting rules; still the operative reporting rules until replaced by implementing acts under Dir. Art. 23(5)) |
| IPR-G | Eionet IPR Guidance v2.0.1 (data flows C, D, E1a, E2a) |
| ETC | ETC HE Report 2024/17, "EEA's revision of the European air quality index bands" |
| EAQI-req | ../EU_AQI_requirements.md (project summary; facts taken from the live EEA index page) |
1. Purpose and scope
- Defines the minimum a traffic station must have so that:
- its measurements meet the Directive's requirements for fixed (or, at least, indicative) measurements;
- its hourly data can be accepted by the national authority into the Eionet E2a up-to-date (UTD) flow;
- the EEA index shows it as a full-colour circle (index computed with the minimum pollutant set for its type).
- Out of scope: background and industrial stations, supersites (Dir. Annex VII), deposition and heavy-metal / PAH sampling, modelling.
- Legal status note: Dir. 2024/2881 must be transposed by 11 December 2026. Until then Directive 2008/50/EC as transposed in Romania (Legea 104/2011) still applies. The siting and data-quality rules below are taken from 2024/2881; most of them are unchanged from 2008/50/EC.
- The EEA index is a communication tool, not a compliance tool (EAQI-req §2). Being on the index does not by itself mean the station meets the Directive; the two requirement sets are listed separately where they differ.
- Access route: a station reaches the index only through the national authority's E2a feed. In Romania that is ANPM / RNMCA. There is no direct upload for private stations (EAQI-req §4.4; IPR-G p. 6–7).
2. What makes a station a "traffic" station
2.1 Classification criteria
The 2024/2881 Directive does not define the term "traffic station". It uses "air pollution hotspot" (Dir. Art. 4(24a)) and "sampling points focused on measuring contributions from road traffic" (Dir. Annex IV C(e)). The "traffic" label comes from the Eionet station classification vocabulary used in reporting:
| Source | Definition |
|---|---|
IPR-G Table 12 (vocabulary http://dd.eionet.europa.eu/vocabulary/aq/stationclassification) |
Traffic: "Located in close proximity to a single major road." (Industrial: close to a single industrial source or area. Background: neither traffic nor industrial.) |
| IPR Annex II D(ii)(22) | Classification "in relation to predominant emission sources relevant for the measurement configuration for each pollutant". So the classification is set per sampling point / pollutant. In practice the whole station is usually "traffic". |
| Dir. Art. 4(24a) | "Air pollution hotspot": locations within a zone with the highest concentrations to which the population is likely to be exposed, including where levels are strongly influenced by "nearby congested and heavily trafficked roads". A traffic station is normally the zone's hotspot sampling point for NO2 and PM. |
| Dir. Annex IV B(2)(cc) | Where the objective is to assess the road-traffic contribution, sampling points shall be on "the streets where the highest concentrations occur, taking into consideration traffic volume (representing the largest traffic density in the zone), local dispersion conditions and spatial land use (for example in street canyons)". |
| IPR Art. 2(1) | A "station" is a location where measurements are taken at one or more sampling points at the same site, within an area of some 100 m². |
2.2 Area of representativeness
| Requirement | Value | Source |
|---|---|---|
| Air sampled must, where feasible, represent a street segment of | ≥ 100 m in length | Dir. Annex IV B(2)(b) |
| Avoid measuring micro-environments in the immediate vicinity of the sampling point | qualitative | Dir. Annex IV B(2)(b) |
| Location should, as far as possible, be where sensitive or vulnerable groups are exposed (residential areas, schools, hospitals, offices) | qualitative | Dir. Annex IV B(2)(cb) |
| Must be ambient air accessible to the public. No locations within 25 m of major junctions | 25 m | Dir. Annex IV C(e); IPR-G p. 47 (model assessment note) |
2.3 Area type (Eionet areaclassification, IPR-G Table 14)
| Area class | Criterion (abridged) | Typical for traffic? |
|---|---|---|
| Urban | Continuously built-up street front, buildings ≥ 2 floors | Yes, most common |
| Suburban | Largely built-up, detached buildings, mixed with non-urbanised areas | Yes |
| Rural (near city / regional / remote) | Everything else | Rare. The vocabulary allows it (e.g. motorway sites), but the Directive's traffic hotspot logic targets exposed populations. |
The EEA index map has a filter for traffic stations only and one for non-traffic stations only (EAQI-req §3.1). The classification in Dataset D decides which pollutant minimum applies (section 8).
3. Mandatory and recommended pollutants
3.1 Minimum for full-colour display on the EEA index (ETC §2)
| Pollutant | Status for a traffic station | Reasoning |
|---|---|---|
| NO2 | Mandatory | Main tracer of road-traffic exhaust (diesel NOx). The index needs it for traffic stations (ETC §2). |
| PM2.5 or PM10 (at least one) | Mandatory | Exhaust plus non-exhaust (brake, tyre, road wear, resuspension) particles. Either fraction satisfies the index rule (ETC §2). |
ETC §2: "For traffic stations: Either PM2.5 or PM10 needs to be measured as well as NO2."
O3 is not required for traffic stations, unlike background and industrial stations.
3.2 Recommended additions
| Pollutant | Recommendation | Reasoning / source |
|---|---|---|
| Both PM2.5 and PM10 | Strongly recommended | Both are index pollutants, and both are in the Annex IX(1)(a) list of hourly up-to-date public information. Annex III Table 1 counts PM10 and PM2.5 sampling points separately. Measuring both also captures the coarse non-exhaust fraction (PM10 − PM2.5), which is characteristic of roads. |
| NO (and NOx) | Recommended. Comes free with an EN 14211 chemiluminescence analyser. | NOx is in the E2a pollutant list (EAQI-req §4.2). NO/NO2 ratio is a useful traffic-proximity diagnostic. |
| CO | Recommended | Dir. Annex III A(1): for NO2, PM, benzene and CO, each zone's minimum network must include at least 1 sampling point focused on transport emissions. CO is in Annex IX(1)(a) hourly public info and in the E2a list. Not an EEA index pollutant. Reference method EN 14626. |
| Benzene | Optional | Also named in Dir. Annex III A(1) for transport-focused points. Reported as validated data only, not UTD (EAQI-req §4.2), so it has no effect on the index. Reference method EN 14662 (non-continuous or GC). |
| O3 | Not required; generally not recommended at kerbside | Dir. Annex IV C(g): O3 sampling points must be > 10 m from the nearest road, while traffic inlets must be ≤ 10 m from the kerbside (Annex IV C(e)). The two criteria practically exclude each other. At kerbside, fresh NO titrates O3, so measured levels are low and unrepresentative. If O3 is still measured, it adds a sub-index on the EEA map (all available pollutants are used, ETC §2). |
| SO2 | Not required | Index pollutant, but road traffic is not a relevant SO2 source (low-sulphur fuels). Not gap-filled by the EEA (EAQI-req §3.3). |
| UFP / BC | Optional | Dir. Annex III D asks for at least 1 UFP sampling point per 5 million inhabitants where high UFP concentrations are likely, which is typically traffic. This is a national network obligation, not a station minimum. No effect on the index. |
4. Measurement requirements
4.1 Time resolution, units, reference conditions
| Item | Requirement | Source |
|---|---|---|
| Averaging period for reporting | Hourly means for gases. Automatic PM monitors are aggregated to hourly means. Half-hour raw data must be averaged to the hour before transmission. | IPR-G §E(1), p. 48 |
| Index computation | Hourly values for all pollutants, including PM, since 4 July 2025 | ETC §2; EAQI-req §2 |
| Unit | µg/m³ (CO: mg/m³) | Dir. Annex I, Annex V |
| Gases (NO2, CO, O3, SO2) | Volume standardised to 293 K and 101.3 kPa | Dir. Annex VI C |
| PM | Sampling volume at ambient temperature and pressure | Dir. Annex VI C |
| Operation | Fixed measurements of SO2, NO2, CO, O3, PM10, PM2.5 must run continuously over the full calendar year | Dir. Annex V B |
| Fixed measurement definition | Constant location for ≥ 1 calendar year | Dir. Art. 4(19) |
4.2 Reference methods and equivalence (Dir. Annex VI)
| Pollutant | Reference method | Equivalence route |
|---|---|---|
| NO2 / NOx | EN 14211:2012 chemiluminescence | Dir. Annex VI B(1): any method shown to give equivalent results (Commission equivalence guidance) |
| PM10, PM2.5 | EN 12341:2023 gravimetric | Annex VI B(1): automatic monitors meeting EN 16450:2017 with a demonstrated consistent relationship. Results must be corrected to reference-equivalent values. Correction should be applied retroactively where appropriate (B(4)). |
| CO (recommended) | EN 14626:2012 NDIR | as above |
| O3 (if measured) | EN 14625:2012 UV photometry | as above |
| SO2 (if measured) | EN 14212:2012 UV fluorescence | as above |
- All PM data reported to E2a (and E1a) must be equivalent to the reference method for fixed-measurement purposes. Indicative data are supplied with the correction factor where required (IPR-G §E(1)).
- The Dataset D record must state the method, equipment and demonstration of equivalence with a documentation web link (IPR Annex II D(ii)(9)–(13)).
- Test reports from accredited laboratories in other Member States must be accepted (Dir. Annex VI D).
- Low-cost sensor systems can only be indicative at best. Their performance class follows CEN/TS 17660-1:2021 (gases) and CEN/TS 17660-2:2024 (PM), where Class 1 targets the indicative-measurement DQO (EAQI-req §6.5). The national authority decides whether to accept such data into E2a. Most authorities, ANPM included as far as known, currently report only reference or equivalent instruments. Not verified for ANPM specifically.
4.3 Maximum measurement uncertainty (Dir. Annex V A, 95 % confidence, near the limit value)
Short-term means (Annex V A Table 2):
| Pollutant / averaging | Fixed: absolute | Fixed: relative | Indicative: absolute | Indicative: relative |
|---|---|---|---|---|
| NO2 – hourly | 30 µg/m³ | 15 % | 50 µg/m³ | 25 % |
| NO2 – daily | 7.5 µg/m³ | 15 % | 12.5 µg/m³ | 25 % |
| PM2.5 – 24 h | 6.3 µg/m³ | 25 % | 8.8 µg/m³ | 35 % |
| PM10 – 24 h | 11.3 µg/m³ | 25 % | 22.5 µg/m³ | 50 % |
| CO – 8 h | 1.0 mg/m³ | 10 % | 2.0 mg/m³ | 20 % |
| CO – 24 h | 0.6 mg/m³ | 15 % | 1.0 mg/m³ | 25 % |
Long-term (annual) means (Annex V A Table 1):
| Pollutant | Fixed: absolute | Fixed: relative | Indicative: absolute | Indicative: relative |
|---|---|---|---|---|
| NO2 / NOx | 6.0 µg/m³ | 30 % (15 % before 2030) | 8.0 µg/m³ | 40 % |
| PM2.5 | 3.0 µg/m³ | 30 % (25 % before 2030) | 4.0 µg/m³ | 40 % |
| PM10 | 4.0 µg/m³ | 20 % | 6.0 µg/m³ | 30 % |
Rules (Annex V A):
- Before 2030 the relative values apply. From 2030 the uncertainty must not exceed the absolute or the relative value, whichever is higher.
- Uncertainty is calculated per the relevant EN standard (otherwise JCGM 100:2008 / ISO 5725-5). For indicative measurements without a CEN standard, it follows the Commission equivalence guidance.
- The objectives do not apply to information or alert thresholds.
- Gap in the sources: the Directive sets no hourly uncertainty objective for PM, only 24 h and annual. The index nevertheless uses hourly PM (ETC §2). An hourly PM DQO could not be found in the local sources.
4.4 Minimum data coverage (Dir. Annex V B, % of calendar year with valid data)
| Pollutant | Fixed – annual mean | Fixed – 1 h / 24 h means | Indicative – annual | Indicative – 1 h / 24 h |
|---|---|---|---|---|
| NO2, NOx, CO | 85 % | 85 % | 13 % | 50 % |
| PM10, PM2.5 | 85 % | 75 % | 13 % | 50 % |
| Benzene (optional) | 85 % | – | 13 % | – |
- Normal maintenance must not take place during pollution peaks (Annex V B).
- Data must reach the Commission irrespective of whether coverage is met (Dir. Art. 23(1)). Coverage failures must be made public per sampling point (Dir. Art. 22(1)(aa)).
- For the index there is an additional practical condition (section 8.3): if the same hour is missing on ≥ 3 of the 4 previous days, the sub-index is not determined.
4.5 Calibration and QA/QC (Dir. Annex V E)
| Requirement | Source |
|---|---|
| All measurements traceable per the harmonised standard for testing and calibration laboratories (i.e. EN ISO/IEC 17025) | Annex V E(1)(a) |
| Operator must have an established QA/QC system with regular maintenance and technical checks. The system is reviewed at least every 5 years by the national reference laboratory (NRL). | Annex V E(1)(b) |
| QA/QC process for data collection and reporting. Participation in Union-wide QA programmes. | Annex V E(1)(c) |
| NRL accredited for the reference methods. Takes part in JRC intercomparisons at least every 3 years. | Annex V E(1)(d)–(e) |
| Reported data are deemed valid except data flagged as provisional | Annex V E(2) |
| Zero/span check frequencies, converter efficiency tests (NO2), flow checks (PM) | Set in EN 14211 / EN 12341 / EN 16450. Not verified here. The standards are not in the local sources, so take the frequencies from the standards themselves or from the ANPM/NRL QA manual. |
5. Siting requirements specific to traffic stations
5.1 Macro-scale (Dir. Annex IV B)
| Criterion | Requirement | Source |
|---|---|---|
| Purpose | Measure the road-traffic contribution on the streets with the highest concentrations, considering traffic volume (largest traffic density in the zone), local dispersion and land use (e.g. street canyons) | Annex IV B(2)(cc) |
| Representativeness | Street segment ≥ 100 m long | Annex IV B(2)(b) |
| Exposure | Where the public is exposed for a period significant for the averaging time; preferably near sensitive or vulnerable groups | Annex IV B(2)(cb); Art. 4(24a) |
| Emission data | Siting takes account of national gridded emissions (Dir. 2016/2284), E-PRTR and local inventories | Annex IV B(1) |
| Network context | Each zone needs ≥ 1 transport-focused sampling point for NO2, PM, benzene and CO. Hotspot and urban-background sampling-point counts must not differ by more than a factor of 2. | Annex III A(1) |
5.2 Micro-scale (Dir. Annex IV C, "in so far as practicable")
| Criterion | Requirement | Source |
|---|---|---|
| Distance from major junction edge | ≥ 25 m ("major junction" = one that interrupts traffic flow and causes stop-and-go emissions) | Annex IV C(e) |
| Distance from kerbside | ≤ 10 m ("kerbside" = line separating motorised traffic from other areas) | Annex IV C(e) |
| Inlet height | 0.5 m to 4 m above ground. Higher siting is allowed only at background locations, so it does not apply to traffic. | Annex IV C(b) |
| Free airflow | Arc ≥ 270°, or ≥ 180° for inlets at the building line | Annex IV C(a) |
| Clearance from obstacles | ≥ 1.5 m from buildings, balconies, trees and other obstacles. ≥ 0.5 m from the nearest building if representing the building line. | Annex IV C(a) |
| Direct emissions | Inlet not in the immediate vicinity of sources (e.g. no direct intake from a single exhaust pipe, bus stop idling point, chimney) | Annex IV C(c) |
| Exhaust | Sampler exhaust positioned to avoid recirculation to the inlet | Annex IV C(d) |
| O3 (if measured) | > 10 m from the nearest road. This conflicts with the traffic kerb rule (see §3.2). | Annex IV C(g) |
| Other factors | Interfering sources, security, access, power, communications, visibility, public and operator safety, co-location of pollutants, planning permission | Annex IV C(h) |
5.3 What to document (Dir. Annex IV D; IPR Annex II D(ii))
- Spatial coordinates, detailed maps and compass-point photographs (N, E, S, W) of the surroundings, plus information on spatial representativeness (Annex IV D(2)).
- Justification that the site is representative of the highest levels in the zone (Annex IV D(3)(a)).
- Any deviation from micro-scale criteria, the reasons and the likely impact on measured levels (Annex IV D(3)(c)).
- Measured distances: inlet to kerb, inlet to nearest traffic lane, inlet to nearest building, inlet to edge of nearest major junction, inlet height. These feed Dataset D (section 6).
- Traffic data: assessed traffic volume (vehicles/day), heavy-duty share, speed, street width and façade height if a canyon (section 6).
- The authority reviews site selection at least every 5 years, and the documentation is made public (Annex IV D(9)–(10)). It must be provided to the Commission within 3 months of a request (Dir. Art. 23(4)).
- If the station or a sampling point moves, it needs a new code (IPR-G p. 34).
6. Station and sampling point metadata (Dataset D)
Fields from IPR Annex II D(ii) (numbering as in the Decision) and IPR-G §D(1). Traffic-specific fields are bold.
| # | Field | Notes for a traffic station |
|---|---|---|
| 1 | Measurement configuration ID | One per pollutant sampling point (NO2, PM2.5, PM10, CO…) |
| 2 | European station ID (EoI code) | Format CCXXXXX. For Romania RO + 4 digits + A (Airbase-type), e.g. RO0071A. Assigned by the Member State (IPR-G p. 33–34). |
| 3–6 | Network ID, national station code, station name, municipality | Name = town + street or place, e.g. "Bucuresti Calea Victoriei". Avoid "Centre", "traffic", numbers or codes (IPR-G Table 8). |
| 7–8 | Measurement start/end date, measurement type | Type: automatic / active / passive etc. |
| 9–13 | Method, equipment, detection limit, demonstration of equivalence (+ web link) | Required for every non-reference method (§4.2) |
| 14–15 | Sampling time, sampling interval | 1 h |
| 16–18 | Spatial extent / evaluation / documentation of representativeness | "Where available" |
| 19 | Height of air inlet above ground | 0.5–4 m (§5.2) |
| 20 | Horizontal distance of air inlet from the next building | For traffic stations |
| 21 | Distance of air inlet from nearest lane | For traffic stations |
| 22 | Station classification per pollutant | traffic (vocabulary aq/stationclassification) |
| 23 | Main sources | e.g. Transport (NFR 1.A.3) (IPR-G Table 13) |
| 25 | Station start and end date | |
| 26 | Longitude, latitude, altitude | Decimal degrees with ≥ 4, preferably 5 decimals (~1 m). ETRS89 recommended, and the reference system must be reported (IPR-G §(ix)). |
| 27 | Station documentation incl. maps and photographs (web link) | "Where available". Supports §5.3. |
| 28 | Area classification | urban / suburban (vocabulary aq/areaclassification, IPR-G Table 14) |
| 29 | Distance to major junction | For traffic stations. Must be ≥ 25 m (§5.2). |
| 30 | Assessed traffic volume | For traffic stations (mandatory) |
| 31 | Heavy-duty fraction of traffic | For traffic stations, where available |
| 32 | Traffic speed | For traffic stations, where available |
| 33 | Street canyon – width of street | For traffic stations, where available |
| 34 | Street canyon – mean height of building façades | For traffic stations, where available |
| – | Local dispersion situation | e.g. "street canyon" = continuous buildings on both sides for > 100 m and height/width ratio > 0.5 (IPR-G Table 9). Regional dispersion per IPR-G Table 10. |
| 35–37 | Network name, network operation dates, responsible body | The national network (RNMCA) |
- Units for traffic volume and speed (typically vehicles/day and km/h) are defined in the e-reporting data model. They are not stated in the local sources, so check with ANPM or the Eionet data dictionary.
- Dataset D must be kept current. Incoming UTD data are QA-checked against the latest Dataset D, so register the station before its E2a data start (IPR-G p. 7). A full up-to-date Dataset D is due by 30 September of the following year.
7. Data delivery to the EEA index
| Item | Requirement | Source |
|---|---|---|
| Path | Station → national data provider (ANPM) → Eionet CDR, data flow E2a → EEA UTD database → EEA index app | IPR-G p. 6–7; EAQI-req §4 |
| Frequency | Hourly, all year | IPR-G p. 6 ("transmitted hourly throughout the year") |
| Pollutants accepted in UTD | NO2, NOx, PM10, PM2.5, SO2, O3, CO. Benzene is not a UTD pollutant. | EAQI-req §4.2 (from IPR-G) |
| Content per value (IPR Annex II E) | Sampling point / measurement configuration ID, start and end of the averaging period (with time zone), value, unit, validity flag, verification flag, version | IPR-G §E(1)–(2); EAQI-req §4.2 |
| Validity flag | 1 valid, 2 valid below DL (value given), 3 valid below DL (replaced by 0.5×DL), -99 invalid due to maintenance/calibration, -1 invalid / missing |
IPR-G §E(2) |
| Verification flag | 1 verified, 2 preliminary verified, 3 not verified. Live E2a normally carries 3 (or 2). |
IPR-G §E(2) |
| PM values | Already corrected to EN 12341 equivalence | IPR-G §E(1) |
| Consistency | E2a must match Dataset D (IDs, pollutant, method), Dataset C and later E1a/G | IPR-G p. 6–7 |
| Validated data | E1a replaces E2a, due within 9 months after year end (by 30 September) | Dir. Art. 23(2); IPR-G p. 6 |
| Public information (national) | Hourly up-to-date data per sampling point of SO2, NO2, PM10, PM2.5, CO, O3 | Dir. Annex IX(1)(a) |
| Index obligation (national) | Hourly index on at least SO2, NO2, PM10, PM2.5, O3, building on the EEA index (or using it) | Dir. Art. 22(2) |
- Maximum allowed latency between the end of an hour and its arrival at the EEA is not specified in the local sources. IPR Art. 10(6) only says "on a provisional basis with the frequency appropriate to each pollutant ... within a reasonable timeframe". Agree a concrete target with ANPM. Arrival within the hour is the practical goal, so the value counts for the current index update.
- Arrival at the EEA can be checked through the EEA Download Service, dataset "Unverified data transmitted continuously (UTD/E2a)" (EAQI-req §4.2).
8. How the station will be shown on the EEA index
8.1 Station index
- A sub-index is computed per pollutant from the hourly value. The station index is the worst (highest) sub-index (ETC §2).
- All pollutants available at the station are used (NO2, PM10, PM2.5, O3, SO2), not only the minimum set (ETC §2; EAQI-req §3.2).
8.2 Full colour vs semi-transparent (ETC §2)
| Situation for a traffic station | Display |
|---|---|
| NO2 and (PM2.5 or PM10) available | Full-colour circle in the category colour |
| Minimum set incomplete (e.g. only PM, or only NO2), index good / fair / moderate | Semi-transparent grey circle |
| Minimum set incomplete, index poor / very poor / extremely poor | Semi-transparent circle in the category colour |
8.3 Missing hours and gap-filling (EAQI-req §3.3, from the EEA index page)
- Missing hourly values are gap-filled with downscaled CAMS model data: difference method for NO2, PM2.5, PM10; multiplicative for O3; no gap-filling for SO2. Gap-filled values are marked with an asterisk.
- If measured values for the same hour are missing on ≥ 3 of the 4 previous days, that pollutant's sub-index is not determined. For a traffic station, losing NO2 or both PM fractions this way would break the minimum set. That the station then turns semi-transparent is an inference from §8.2, not explicitly confirmed in the sources.
- These rules come from the live EEA index page as compiled in EAQI-req. They are not in ETC 2024/17 and were not re-verified against the page for this document.
- UTD data on the index are not formally verified.
8.4 Index bands for the mandatory pollutants (hourly, µg/m³; ETC Table 5.2, in force since 4 July 2025)
| Pollutant | Good | Fair | Moderate | Poor | Very poor | Extremely poor |
|---|---|---|---|---|---|---|
| NO2 (1 h) | 0–10 | 11–25 | 26–60 | 61–100 | 101–150 | > 150 |
| PM2.5 (1 h) | 0–5 | 6–15 | 16–50 | 51–90 | 91–140 | > 140 |
| PM10 (1 h) | 0–15 | 16–45 | 46–120 | 121–195 | 196–270 | > 270 |
(Optional pollutants, if measured: O3 0–60 / 61–100 / 101–120 / 121–160 / 161–180 / > 180; SO2 0–20 / 21–40 / 41–125 / 126–190 / 191–275 / > 275. Same table.)
- The NO2 "very poor" upper limit (150) equals the NO2 information threshold (ETC §5; Dir. Annex I).
- Health messages are unchanged from the earlier index (ETC Table 6.1; EAQI-req §2.4).
- Do not use the pre-July-2025 bands (24 h running PM means, NO2 0–40 "good", and so on) (EAQI-req §2.2).
- Rounding of non-integer hourly values at band edges (e.g. 10.4 µg/m³ NO2) is not specified in the sources.
9. Checklist
Sensors / instruments
- NO2 analyser installed (EN 14211 chemiluminescence, or a method with demonstrated equivalence)
- At least one PM monitor installed (PM2.5 or PM10; EN 12341 reference or EN 16450 automatic with equivalence)
- Both PM2.5 and PM10 measured (recommended)
- NO and NOx recorded from the NO2 analyser (recommended)
- CO analyser per EN 14626 considered (recommended for traffic; not an index pollutant)
- O3 deliberately not measured at kerbside, or its siting conflict with Annex IV C(g) documented
- Demonstration-of-equivalence report available for every non-reference instrument
- PM correction factor to EN 12341 established by co-location and applied to all output
- Measurement uncertainty meets Annex V fixed DQOs (NO2 hourly 15 %, PM 24 h 25 %), or at least the indicative ones (25 % / 35–50 %)
- Detection limit documented per pollutant
Data format
- Hourly mean per pollutant (sub-hourly raw data averaged to the hour)
- Units µg/m³ (CO mg/m³)
- Gases standardised to 293 K / 101.3 kPa; PM at ambient conditions
- Each value has start and end time with time-zone offset
- Validity flag (1 / 2 / 3 / -99 / -1) on every value
- Verification flag (3 = not verified for live data) on every value
- Maintenance and calibration hours flagged -99, never sent as valid values
- Index computed locally (if displayed) with ETC Table 5.2 bands and the worst-sub-index rule
Siting
- Site on a street with high traffic density and public exposure (Annex IV B(2)(cc), (cb))
- Air sampled represents a street segment ≥ 100 m long
- Inlet ≤ 10 m from the kerbside
- Inlet ≥ 25 m from the edge of the nearest major junction
- Inlet height between 0.5 m and 4 m above ground
- Free airflow arc ≥ 270° (≥ 180° at a building line)
- Inlet ≥ 1.5 m from buildings, balconies, trees, obstacles (≥ 0.5 m from building at a building line)
- No direct local emission source at the inlet; exhaust does not recirculate
- Maps and N/E/S/W compass photographs taken
- Any deviation from micro-scale criteria documented with reason and expected impact
Metadata
- EoI station code assigned by ANPM (
RO####A) - Station name follows IPR-G Table 8 (town + street)
- Coordinates with ≥ 5 decimals, altitude, reference system (ETRS89)
- Station classification = traffic, for each pollutant
- Area classification = urban or suburban
- Inlet height recorded
- Distance of inlet to next building recorded
- Distance of inlet to nearest lane recorded
- Distance to major junction recorded
- Assessed traffic volume recorded
- Heavy-duty fraction, traffic speed, street width, façade height recorded where available
- Local dispersion situation (e.g. street canyon) and main source (Transport) recorded
- Method, equipment and equivalence documentation (web link) recorded per sampling point
- Dataset D record submitted by ANPM before E2a data start
Delivery
- Agreement with ANPM / local APM to integrate the station into RNMCA reporting
- Hourly data feed in the format ANPM ingests, with an agreed latency target
- Sampling point IDs in the feed match Dataset D
- Local buffering and back-fill so outages do not lose hours
- Station arrival verified in the EEA Download Service (UTD/E2a dataset)
- Station visible as a full-colour traffic circle on the EEA index map
QA
- QA/QC system with documented maintenance and technical checks (Annex V E(1)(b))
- Calibrations traceable to accredited (EN ISO/IEC 17025) standards
- Zero/span and flow checks at the frequencies required by EN 14211 / EN 12341 / EN 16450
- Data coverage target ≥ 85 % (NO2) and ≥ 75 % hourly / 85 % annual (PM) for fixed status; ≥ 50 % hourly as an absolute minimum (indicative)
- No same-hour gaps on ≥ 3 of 4 consecutive days (keeps the EEA sub-index determined)
- Maintenance not scheduled during pollution peaks
- Periodic co-location or audit by the national reference laboratory
- Site documentation reviewed at least every 5 years, and the station recoded if it moves