Heating season means pollution season
Bad air quality is one of the most serious threat to public health. Starting in autumn it becomes even more dangerous. Power consumption related to the heating system and road traffic is increasing, which leads to the increase of air pollution as well. What is more, lower temperatures are favorable conditions to keep air quality poor.
This article presents how NO2 pollution changes from September to November in respect of temperature. Two datasets were used in order to achieve the objective:
Sentienel-5P – NO2 Tropospheric Column Number Density product (NO2 TVCD):
- Obtained from CREODIAS
- Processed by HARP (see the document: Processing Sentinel-5P data on air pollution using Jupyter Notebook)
- Monthly and weekly averages
ERA-5 Land hourly – Air temperature at 2m above the ground (T):
- Obtained from Climate Data Store
- Monthly and weekly averages
Firstly, let’s take a look at the variability of NO2 pollution and temperature through the year 2023.
In general, monthly NO2 TVCD is high in winter, at the beginning of spring, and in autumn. It corresponds well to low monthly temperatures in those periods. It is also clearly observed on maps below, which show the spatial distribution of NO2 TVCD over Poland from September to November 2023. In September, hotspots of air pollution were observed mostly over big cities and powerplants. In October, when heating season started, poor air quality spread over entire Poland.
Now, let’s focus on autumn (September, October and November) and try to find the exact moment when NO2 TVCD started to increase rapidly.
NO2 air pollution started to rise from the beginning of September, with 0.50 Pmolec/cm2 per week. In October, the increase of air pollution was higher – 0.65 Pmolec/cm2 per week. What is more, between 9th and 22nd of October, the first huge rise in air pollution was observed (c.a. 1.30 Pmolec/cm2 in one week). It corresponded to the decrease of temperature to below 10°C. A similar increase of NO2 and the decrease of temperature was noticed in November, when air pollution raised more than a 2 Pmolec/cm2 in two weeks, and temperature decreased to almost 5°C. In general, in November, the average increase of NO2 TVCD over Poland was c.a. 1 Pmolec/cm2 per week.
At the end of October, high values of NO2 TVCD were observed over big cities and the area between Warsaw, Katowice, and Rzeszów. However, the number of observations decreased (due to cloudiness), which affected the quality of data. Not even one observation was made over some areas in northern Poland.
It must be pointed out that along with autumn and winter, the number of cloudless and valuable observations significantly decreases, which could lead to some misleading conclusions. In this case, there were still c.a. 10 valuable observations per month, which allowed for the monthly analysis. There was a smaller number of observations per week.
To sum up, a simple case of the relation of air pollution to air temperature was presented in this article, in particular referring to the start of the heating season. It was confirmed that October is the start of poor air quality in Poland.
Senitnel-5P data, L2__NO2___ product, OFFL processing mode were obtained on CREODIAS.
Author: Patryk Grzybowski, Data Scientist at CloudFerro