HomeBlogWhich phenomena influence smog’s formation? You may be surprised

Which phenomena influence smog’s formation? You may be surprised

Dust from the Sahara desert, frost and fireworks: many phenomena have a significant impact on the air we breathe. Which situations require us to be particularly careful about smog? Experts from Airly have checked.

Text: Data analysis – Marcin Szwagrzyk, Editors – Marcin Gnat


In Poland, the main source of particulate matter air pollution is domestic heating with coal. 

The amount of carbon needed to heat homes naturally depends on the temperature outside, so air quality usually worsens with colder temperatures. In recent years, Poland has had mild winters, and this was one of the reasons for a small improvement in air quality.

However, a wave of harsh frosts has hit Poland recently. The animation below clearly shows how in Podlasie – a region that usually has good air quality compared to the rest of the country (due to the low population density and good ventilation) – frost resulted in high concentrations of pollution, especially on February 5 and 7.

In other regions of Poland, especially in the south which is well-known for its pollution, you can also see how frost causes the deterioration of air quality.

Heat waves

Frosty weather clearly causes the deterioration of air quality through an increase in the concentration of particulate matter. But what about hot weather? Is it really better when it’s warmer?

In order to answer this question, we analyzed data from our sensors installed in the UK, taking into account the daily course of gas concentration. The chart below shows the average daily runs for all days in 2020; the color of the line indicates air temperature on the day. It clearly shows that the highest ozone concentrations were achieved during the warmest days.

Dust from the Sahara desert

We have also seen quite an unusual phenomenon recently – yellow and orange snow has fallen in many European countries (link). This is due to dust from the Sahara, transported across the Mediterranean Sea by high-altitude winds.

Air quality monitoring stations have captured this phenomenon. An increase in the concentration of suspended dust (PM10) moving towards the north is visible in the animation below from February 5 – initially in the Balearic Islands and on the southern coast of Spain, then in mainland Spain, and then in the following days in southern France.


Fireworks are another interesting phenomenon that our sensors can capture. The animation below shows PM10 readings from New Year’s Eve from our sensors in four different cities, located in four different time zones. Something starts happening as midnight approaches and people begin to greet the new year.


It is common knowledge that air pollution is solely the result of human activity. There is no doubt that it is us – humans – who contribute the most to the quality of the air we breathe. We do this by heating houses with poor-quality coal or rubbish, contributing to heavy car traffic or developing heavy industry that is unfriendly to the environment. However, there are specific phenomena that can make good air suddenly bad, and bad air often becomes very bad. Therefore it is worth monitoring air quality on an ongoing basis to be aware of what you are breathing, and this way you can react to it appropriately. Let’s not forget that air quality has a significant impact on our health and well-being.

View MyAirly map to check live air quality map from your area.

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