Air Quality Scale in Poland

Posted on September 3rd 2015

Inspekcja Ochrony Środowiska.
(Inspection of Environmental Protection)

The Air Quality data for Poland has been available for a while, but we recently got few questions about the AQI scale used by the Inspekcja Ochrony Środowiska, i.e. the regional inspections of Environmental Protection, and how it differs with the scale used on the World Air Quality Index project. One of them is from Sylwia, who asked:

I am confused with all those numbers, and why there is a difference with the numbers shown on the Warsaw EPA website.

Could you please kindly inform me about the source of the data in Warsaw and the reliability of the data you provide with?
This is actually a very good question, since, when it comes to data, no one should take data as "granted" (refering to the excellent TED talk from Talithia Williams on 'Own your body's data'). This is also the reason why the World Air Quality Index project exists, i.e. to explain every one how to understand the number behind air pollution.


Air Quality Data Sources

To answer the first question about our source of the data, the World Air Quality Index service only uses officially measured and published data. In other words, at the World Air Quality Index project we do not operate any Air Quality monitoring ourselves. Instead we rely on each country's EPA to operate and maintain their own monitoring network [1]

In the case of Warsaw, the data is measured by the Regional Inspectorate for Environmental Protection in Warsaw (Wojewódzki Inspektorat Ochrony Środowiska w Warszawie). They provide the data using both the Polish AQI (called Indeks Jakości Powietrza, aka IJP), as well as the raw concentrations for PM2.5, PM10, Ozone, etc. You can see the data from their map service.

Polish AQI: Indeks Jakości Powietrza

The IJP (Indeks jakości powietrza) is defining its own color coding and scale, which is summurized in the table below. Note that the color standard used by the IJP is not completely equivalent to the US EPA AQI standard, but that's something we will look into details later.

Air quality Recommendations for population
0-1 Very good (Excellent)
Bardzo dobry
The air quality is good. The air pollution pose no threat. The conditions ideal for outdoor activities.
Jakośc powietrza jest dobra. Zanieczyszczenia powietrza nie stanowią zagrożenia. Warunki idealne na aktywności na zewnątrz.
1-3 Good
Air quality is still good. The air pollution pose minimal risk to exposed persons. Conditions very good for outdoor activities.
Jakość powietrza jest wciąż dobra. Zanieczyszczenia powietrza stanowią minimalne zagrożenie dla osób narażonych na ryzyko. Warunki bardzo dobre na aktywności na zewnątrz.
3-5 Moderate
Air quality is acceptable. Air pollution can endanger people at risk. Conditions good for for outdoor activities.
Jakośc powietrza jest akceptowalna. Zanieczyszczenia powietrza mogą stanowić zagrożenie dla osób narażonych na ryzyko. Warunki dobre na na aktywności na zewnątrz.
5-7 Satisfactory
Air quality is average. The air pollution pose a threat for people at risk * which may experience health effects. Other people should limit spending time outdoors, especially when they experience symptoms such as cough or sore throat.
Jakośc powietrza jest średnia. Zanieczyszczenia powietrza stanowią zagrożenie dla osób narażonych na ryzyko* które mogą odczuwać skutki zdrowotne. Pozostałe osoby powinny ograniczyć spędzanie czasu na zewnątrz, zwłaszcza gdy doświadczą takich symptomów jak kaszel lub podrażnione gardło.
7-10 Bad
Air quality is bad. People at risk * should avoid to go outside. The rest should be ograniczyć.Nie are recommended for outdoor activities.
Jakość powietrza jest zła. Osoby narażone na ryzyko* powinny unikać wyjść na zewnątrz. Pozostali powinni je ograniczyć.Nie zalecane są aktywnośći na zewnątrz.
10+ Hazardous
Bardzo zły
The quality of air is dangerously wrong. Those at risk should be avoided to go outside. The others should limit the output to minimum.Wszelkie outdoor activities are discouraged. Jakośc powietrza jest niebezpiecznie zła. Osoby narażone na ryzyko powinny bezwzględnie unikać wyjść na zewnątrz. Pozostali powinni ograniczyć wyjścia do minimum.Wszelkie aktywności na zewnątrz są odradzane.

Indeks Jakości Powietrza (IJP) Calculation

The IJP is calculated using a formula which takes into account the concentration of several pollutants. Almost every single country is haivng into own formula, and in the case of Poland, the "max"-based formula is used:
$$IJP = max( {O_3(1h) \over 120}, {NO_2(1h) \over 120}, {SO_2(1h) \over 120}, {CO(1h) \over 120}, {PM_{10}(1h) \over 100}, {PM_{2.5}(1h) \over 60}, {Benzen(1h) \over 40} ) x 5.$$
That might look slightly barbarian, but actually, this formula is very similar to the one used by the US EPA (and therefore on the World Air Quality Index project), except for major 4 differences:
  • The IJP scale goes from 0 to 10, while for the US EPA, it goes from 0 to 500. Note that other standard like the Hong Kong AQHI standard are also using scale from 0 to 10, this is completely fine.

  • The breakpoints used in the IJP are linear for each pollutant, while for the US EPA they are not. The breakpoints used in the US EPA standard are explained in this article.

  • The IJP is including Benzen in the list of pollutants, while it is not for the US EPA. This is a very positive point for the IJP since Benzen is known to be highly cancerous.

  • The IJP is based on 1 hour readings, while the US EPA standard is theorically based on 24 hours averaging. Again, this is a very good point of the IJP, since we are promoting the universal use of 1 hour readings through our Instant Cast reporintg.

US EPA's AQI and Poland's IJP comparison

Because graphics are better than long sentences, the following interactive graphics is a compariosn of the AQI and IJP scales for PM2.5 and PM10. You can just move your cursor over the graph to see the compared AQI, IJP and raw concentration.

  • PM2.5 is most often the dominent pollutant (compared to PM10), so we will look more carefully at PM2.5 in this article.
  • The European Common Air Quality Index (CAQI) is added for reference purpose, but it will not be used in the analysis.

Understanding the differences

When comparing the IJP and AQI scales for PM2.5, the confusion can come from both ends of the scale:
  • When the Air Quality is Good, a Moderate reading using the US EPA standard is equivalent to a Good (Dobry) with the IJP. And a Moderate (Umiarkowany) using the IJP corresponds to a Unhealthy for Sensitive Groups using the US EPA standard.

  • When the Air is polluted, the IJP standard is setting a very conservatively low threshold, at such level that a Unhealthy reading using the US EPA standard can be equivalent to a Harzardous (Bardzo zły) with the IJP.
The four graphs below summurize the differences between the two standards for the station Komunikacyjna in Warsaw for the last 5 days (PM2.5 on the left, and PM10 on the right).

PM2.5 US EPA AQI (Air Quality Index) - Instant Cast based:
PM2.5 POLAND IJP (Indeks jakości powietrza):
PM10 US EPA AQI (Air Quality Index) - Instant Cast based:
PM10 POLAND IJP (Indeks jakości powietrza):

One can clearly see the equivalence between the IJP green and AQI yellow for the PM2.5 scales (on the left). If one abstract this color swapping difference, then it is obious that both scales report similar level of pollution.

As concerns PM10, while for the US EPA AQI, the index is always lower than the PM2.5 index, for the IJP, the PM10 index is actually similar or higher then the PM2.5 index. Usually, one expects PM2.5 to be more harmfull than PM10 (as explained in this article), so we will have to come back on this difference in a later article (especially looking at the correlation factor between PM10 and PM2.5 based on empiral data for US, Europe and Poland).

About the other pollutants

Among all the other pollutants, Ozone (O3) is the one most likely to be the second dominent pollutant. It is already known that the US EPA 1-hour Ozone standard is not so conservative compared to other existing standards (see this article), and the IJP confirms this rule. The two graphs below show the Ozone Index for both AQI and IJP.

US EPA AQI (Air Quality Index) - Instant Cast based:

POLAND IJP (Indeks jakości powietrza):

Note that the Ozone scale for the US EPA AQI requires concentrations to be expressed in ppb, while for the IJP it is mg/m3.

Note that the IJP Ozone breakpoints defined on shows similar breakpoints for the 1-hour and 8-hours levels; we assume that this is a typo-mistake since one would expect lower breakpoint level for the 1-hour compared to the 8-hour levels. We are contacting the Warsaw EPA and will update this article based on their answer.

The other pollutant worth having a deeper look at is the Benzen, since the IJP is one of the rare scale taking into account Benzen in the Index calculation. Fortunately, the corresponding index for the last 10 days shows that the benzen concentation is always within the [0-1] "very good" range, so not a "daily problem" like PM2.5 can sometime be.


On one side, there are some very good improvements in the Indeks Jakości Powietrza standard defined by the Polish EPA: Using 1-hour readings, including more pollutants like Benzen and lowering the Hazardous level threshold; All those should be promoted worldwide and we will be looking at extending the World Air Quality Index project AQI calculation to also take into account Benzen.

On the other side, trying to compare apple-to-apple the IJP and AQI is not straightforward. When plotting the composite AQI for both IJP and AQI (see graphs below), it looks more like comparing apple and bananas. This is, according to our experience, the most confusing factor when comparing figures provided by different websites.

Last, the key learning is to remember as that each scale has its own specificity, and the most important is to keep the diversity in the scales: We are starting to believe that having only one unique scale might not be the right solution, and we are now working on a global solution which will allow users the select the scale which best fits their needs.

US EPA Composite AQI (Air Quality Index)
Poland Composite IJP (Indeks jakości powietrza)
EU Composite CAQI (Common Air Quality Index)
Note: the composite calculation is based on PM2.5, PM10 and Ozone only.


0 .. 50
Good Air quality is considered satisfactory, and air pollution poses little or no risk 0 .. 1
Bardzo dobry
Very Good
Tidak ada efek
50 .. 100
Moderate Air quality is acceptable; however, for some pollutants there may be a moderate health concern for a very small number of people who are unusually sensitive to air pollution. 1 .. 3
Terjadi penurunan pada jarak pandang
100 .. 150
Unhealthy for Sensitive Groups Members of sensitive groups may experience health effects. The general public is not likely to be affected. 3 .. 5
Jarak pandang turun dan terjadi pengotoran debu di mana-mana
5 .. 7
Meningkatnya sensitivitas pada pasien berpenyakit asthma dan bronhitis
150 .. 200
Unhealthy Everyone may begin to experience health effects; members of sensitive groups may experience more serious health effects
7 .. 10
Tingkat yang berbahaya bagi semua populasi yang terpapar
10 ..
Bardzo zły
Tingkat yang berbahaya bagi semua populasi yang terpapar
200 .. 300
Very Unhealthy Health warnings of emergency conditions. The entire population is more likely to be affected.
300 .. 500
Hazardous Health alert: everyone may experience more serious health effects

Breakpoints used for the IJP:
PM10 - 1h PM10 - 24h NO2 - 1h CO - 8h O3 - 1h O3 - 8h SO2 - 1h SO2 - 24h Indeks jakości powietrza
Bardzo dobry 0-20 0-20 0-40 0-2000 0-24 0-24 0-70 0-25 0-1
Dobry 20-60 20-60 40-120 2000-6000 24-72 24-72 70-210 25-50 1-3
Umiarkowany 60-100 60-100 120-200 6000-1000 72-120 72-120 210-350 50-100 3-5
Dostateczny 100-140 100-140 200-280 1000-14000 120-168 120-168 350-490 100-125 5-7
Zły 140-200 140-200 280-400 >14000 168-240 168-240 490-700 >125 7-10
Bardzo zły >200 >200 >400 >240 >240 >700 >10


Note: This article is part of a series on Worlwide Air Quality scales.

For more information about specific countries or continent, please refer to thoses articles:
Thailand and Malysia
Hong Kong / Canada (Air Quality Health Index)
South America
Quebec and Montreal
For information about the 24 hours averaging used or Ozone and Particulate Matter (PM2.5), please refer to those two articles: Ground Ozone Index - PM2.5 Instant Cast

[1] The monitors are anyways so expensive, estimated 15K€ each, that we could not afford it.

Click here to see all the FAQ entries
  • Nitrogen Dioxyde (NO2) in our atmosphere
  • Ozone AQI Scale update
  • Kriging Interpolation

  • Read or publish comments (they rely on Disqus)


    本网站采用的污染指数和颜色与EPA是完全相同的。 EPA的指数可以从 AirNow上查到

    0 - 50一级(优)空气质量令人满意,基本无空气污染各类人群可正常活动
    51 -100二级(良)空气质量可接受,但某些污染物可能对极少数异常敏感人群健康有较弱影响极少数异常敏感人群应减少户外活动

    如果你想了解更多有关空气质量与污染,详见维基百科或者 AirNow

    有关健康建议详见北京的Richard Saint Cyr MD医生的博客

    注意事项: 所有空气质量数据在发布时均未经验证,并且为了保证数据质量,这些数据可能随时被修改,恕不另行通知。 世界空气质量指数项目在编制此信息的内容时已经运用了所有合理的技能和谨慎,在任何情况下世界空气质量指数项目团队或其代理人将不会为由于提供此数据而直接或间接引起的伤害、合同损失、侵权及其他任何损失负责。



    Temperature unit: