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Thanks to our calculator, you will learn what amount of benzo[a]pyrene goes into your lungs throughout a year of normal breathing. We will convert it into the number of cigarettes you have to smoke to reach such a high dosage. Just choose your city and type in the average time you spend outside daily. In the following text, you will also learn the definition of smog and see where it comes from. You will distinguish between various types of smog and read about its components. You will understand how our smog calculator converts carcinogenic benzo[a]pyrene in the surrounding air into smoked cigarettes. Hopefully, you will get scared by the detailed list of the harmful effects of smog on our bodies and health.

Smog: what is it exactly?

Smog is an atmospheric phenomenon that takes place when air merges and mixes with smoke, fumes, and other contaminants. Also, the word “smog” was created by combining the words “smoke” and “fog”. Doctor Henry Antoine Des Voeux is believed to be the first man who used it. He coined this term to describe the weather phenomena in London in the winter of 1905. Even then, people realized that smoky fog was present more often in huge urban and industrial centers than in rural areas.

Are you a smoker? Or maybe you have recently quit smoking? Try our quit smoking calculator to estimate your potential savings or the smoking calculator to see how much longer you'll live without smoking.

Types of smog

There are two types of smog:

London-type smog, which emerges in winter months in cities of temperate zone areas (e.g., most of Europe and northern parts of the US). It contains mostly toxic substances that are created during the burning of coal or other fuels.

Los Angeles type smog, or photochemical smog, emerges in summer months in subtropical climate zones. The most common sources include vehicle engines and oil refineries. The substances emitted by them to the atmosphere undergo additional photochemical reactions when exposed to sunlight. This way, aldehydes, ozone, peroxyacyl nitrates, and other hydrocarbons are produced.

Do you know what you're breathing with?

A dark winter morning. You put on your shoes and set off to work. Once you open the front doors, an unpleasant, biting, ice-cold air gets into your nostrils. Your bronchi contract, especially if you have recently gone through a respiratory infection. You start to suffocate. Unfortunately, it will not get any better. These sensations will accompany you all the way to the bus stop, work, or school. Tightening your scarf and covering your nose doesn't help at all. A typical, charming morning walk for millions of people suffering from smog around the world. Do we even think about what exactly causes these unpleasant sensations? What toxic substances are hiding under the “smog” label?

With each breath we inhale, we take in:

  • Carbon oxides: CO₂ and CO. The second one is a molecule that binds irreversibly with hemoglobin in our blood, disturbing the transport of oxygen and causing countless deaths of people with leaking installations of stoves that are used to heat houses,
  • Sulfur oxides (SO₂) and nitrogen oxides (NO₂), which cause precipitations of acid rains when mixed with atmospheric water,
  • Soot and dust – including particulate matter (PM).

Particulates PM₂.₅ or maybe PM₁₀? What is it all about?

Particulates present in smog are bonded particles of different substances. The most commonly detected types include polycyclic aromatic hydrocarbons (including carcinogenic benzo[a]pyrene), heavy metals, dioxins, and furans. Scientists measure concentrations of particulates of different sizes in the air. Particulates PM₁₀ are less than 10 micrometers in diameter. For comparison, a typical human hair has a diameter of 60 micrometers. Particulates PM₁₀ accumulate mainly in the throat, larynx, and trachea. Particulates PM₂.₅ with a diameter of under 2.5 micrometers are even more dangerous. Such a small size lets them pass freely through the nose, throat, larynx, trachea, and bronchi and get to the alveoli of the lungs, where they can accumulate and enter the blood. It has been shown in recent studies, that they can even get into our brains!


Particulates present in smog also contain benzo[a]pyrene. It belongs to a group of polycyclic aromatic hydrocarbons. It is heavily carcinogenic. People smoking cigarettes should be aware that in smoke from one cigarette, there are around 14.86 nanograms of benzo[a]pyrene. Unfortunately, people who are free from this terrible addiction cannot feel safe. Apart from spending time among smokers and so-called passive smoking (inhaling cigarette smoke from a person smoking nearby), they can get exposed to benz[a]pyrene while taking a simple winter walk. Benz[a]pyrene is produced during the ineffective burning of coal, rubbish, and plastics in local boilers and house stoves used for heating. It's saddening that a forest of chimneys emitting poisonous smoke is still a typical winter sight in many cities around the world. Thanks to our calculator, you can count how many cigarettes you “smoke” during such a walk.

The latest annual report of the European Environment Agency (EEA) for 2016 shows that benzo[a]pyrene is one of the most prominent air pollution problems present in Europe. Up to 91% of the European Union urban population was exposed to the harmful level of B[a]P concentration above the WHO reference. The European Union target value for air pollution states that the annual mean concentration of B[a]P must not exceed 1 ng/m³. However, the World Health Organization (WHO) guidelines say that this concentration should be less than 0.12 ng/m³ to reduce the risk of additional lifetime lung cancer to approximately 1 in 100 000. In the following picture, you can see that only beige dots fulfill WHO standards for B[a]P concentration (source - EEA air quality statistics). Entire central and central-eastern Europe struggles with this carcinogenic compound!

Annual mean BaP concentrations in Europe in 2017.

Air quality standards in Europe

The problem of polluted air, commonly known as smog, is present in the whole world. Are you aware of the consequences of breathing air that contains harmful chemical compounds? What are the permissible concentrations of such substances?

EEA has gathered data from about 2,900 air quality monitoring stations located in 39 countries and prepared an overview and analysis of air quality in Europe from 2000 to 2016. Results are not very attractive because there are six different air elements whose concentration exceeded air quality standards in the last years. The most dangerous are (concerning the EU standards):

  • O₃ - daily ozone concentration measured as an 8-hour mean can exceed a value of 120 µg/m³, but not more than 25 days per year (365 days), averaged over three consecutive years.

  • PM₁₀ - two air quality standards are used simultaneously. In the first case, the daily concentration of PM₁₀ can exceed 50 µg/m³, but not more than 35 days per year (365 days). The second PM₁₀ standard states that the annual average concentration has a limited value of 40 µg/m³.

  • B[a]P - target value of B[a]P annual concentration is 1 ng/m³. It is worth noting that even if you enter this limit into our calculator, you get the equivalence of about 450 cigarettes per year.

To visualize how many people have been exposed to polluted air in recent years, look at the picture below. It can be found in the EEA article about the high level of air pollution across Europe in 2018.

Exposure to polluted air in recent years.

The main sources of smog

One of the primary sources of particulate matter (PM) and dioxins are non-industrial burnings. We are talking about house stoves used for heating, fueled with coal, wood, and, even worse, rubbish (e.g., plastics). Many households still use primitive and ineffective devices (requiring huge loads of fuel to produce a little heat). Another factor influencing this situation is the fact that many houses are poorly isolated, resulting in significant heat loss. This causes the owners to burn more to sustain the desired temperature.

Motorization, especially vehicles with Diesel engines, is a significant source of nitrogen oxides, particulate matter, and polycyclic aromatic hydrocarbons. In 2017, the International Council on Clean Transport (ICCT) published a report which showed that Diesel engines emit 50% more contaminants than it is described in official studies conducted by car producers. The nitrogen oxides emitted by vehicles with Diesel engines were linked to the premature deaths of around 38,000 people in the year 2015 alone.

Although considerably reduced compared to the previous century, industrial emission remains a notable source of particulate matter (PM), polycyclic aromatic hydrocarbons, nitrogen and sulfur oxides, arsenic, lead, cadmium, and mercury.

The effect of smog on our health

What stands behind the sentence “smog has a harmful effect on our health”? Probably most of us already know and do nothing about it. It is easier to think about a problem using general opinions like “smog is unhealthy” or “smoking cigarettes is unhealthy”. It may mean everything and nothing at the same time. It is more acceptable for our minds and conscience. It is more comforting to think that cigarettes that I smoke are harmful to me than that by smoking them, I have hugely increased the risk of developing lung cancer and dying. This is why, in the list below, you will find all the detailed consequences of breathing with smog.

Smog causes:

  • death – the most spectacular example of increased mortality is the famous smog of 1952, which covered the territory of so-called Great London. In a few days, it became a cause of death for about 4,000 people. However, smog kills in the present times too. According to WHO, an estimated 4.2 million premature deaths globally each year can be linked to ambient air pollution – only in 2016, it contributed to 7.6% of all deaths! You can check how many deaths are caused by smog in your country by visiting this website.
  • development and exacerbation of respiratory diseases: asthma, chronic obstructive pulmonary disease, respiratory infections. Children of women exposed to smog while pregnant suffer more often from inflammations of upper and lower respiratory tracks and have less developed lungs than their peers. Additionally, they have an increased risk of lower birth weight, premature birth, and even in-utero death.

Ambient air pollution accounts for 17% of all deaths and diseases from acute lower respiratory infections and 43% from chronic obstructive pulmonary disease.

  • Carcinogenesis – development of cancers – breathing with benzo[a]pyrene may equal smoking from hundreds to thousands of cigarettes a year. According to WHO, ambient air pollution accounts for 29% of all deaths and diseases from lung cancer. Smog also increases the risk of developing bladder, brain, cervical, and many other cancers.

  • Increased blood pressure, higher risk of an ischemic brain stroke (24% of all deaths from a stroke), heart attack (25% of all deaths and diseases from ischaemic heart disease), and exacerbation of chronic heart failure. Contrary to what you might expect, cardiovascular diseases cause most deaths linked to air pollution!

  • Underdeveloped nervous system in children whose mothers were exposed to air pollution during pregnancy, reduced learning capabilities in children and youths, worsening of depression, and reduction of cognitive functions in adults. It is thought that air pollution may even have an impact on the development of Alzheimer’s disease.

  • Huge costs for society – the number of lost working days (days when workers could not get to work because of illness or premature death) is beyond imagination. This causes enormous costs for the country's budget. And we would also have to add the costs of treatment.

Check out our lung cancer risk calculator to find out how much you increase your risk of getting lung cancer by just breathing polluted air!

Final thoughts

The problem of smog affects us all, the whole human population. Together, we can considerably change the world around us and fight the problems that afflict it. It is necessary to increase people's awareness about the impact of their cars and home heating systems on the air quality. How can you counteract the spread of pollution? It doesn't take that much! You can do this through the following:

  • Replacing solid fuels stoves and boilers (e.g., coal, wood) with other heating sources that are less disruptive for the environment (e.g., natural gas, solar collectors). Moreover, in many countries, the expenses are subsidized by the government. Also, stop burning wood and waste in fireplaces at your home - this is the most significant source of harmful substances in the air!

  • Stopping burning plant waste at gardens and fields. Don't burn cut grass, leaves, weeds, or freshly cut branches. Do not throw them into the dustbin. You can even get a fine for this! Instead, let's compost plant waste or pack it in special bags and hand it over to the waste disposal company.

  • Using bicycles or public transport in cities. You will not only limit dust emissions and improve your health but also reduce the nightmare of every city - traffic jams! This option is more frequently possible because, in many cities, there are bicycle stations for residents that can be found around the whole town. With this car vs. bike calculator, you can now estimate how much additional lifespan, money, and... trees you will gain by switching from a car to a bike for your daily commute!

Krakowski Alarm Smogowy (Smog alert of Cracow)

The authors of this calculator would like to thank the social movement of Krakowski Alert Smogowy (Smog Alert of Cracow) – an organization from the Polish city of Cracow, which is heavily polluted with smog. The information on smog gathered by this group was a huge help for us while we were creating the smog calculator. At the same time, we would like to express our admiration and support for the work of Krakowski Alert Smogowy. Thanks to such organizations, societies change, and the walls of conformist human thinking break. We invite and encourage you to visit their web page (in English!) and broaden your knowledge of smog.

How does the smog calculator work?

The thought process is fairly straightforward:

  • An average adult person inhales 20 m³ of air per day, which is, on average, 0.83 m³ of inhaled air per hour.
  • City air contains a certain concentration of benzo[a]pyrene - select a city to obtain an average concentration of benzo[a]pyrene in this location.
  • The air indoors contains about 10% fewer harmful substances.
  • From the above data, you can calculate how much b[a]p an adult inhales per day:
    0.83 m³ × (time_outdoors + 90% × time_indoors) × B[a]P_concentration = B[a]P_mass_inhaled.
  • If you multiply these results by the number of days in a year, you will obtain B[a]P mass inhaled during one year.
  • We know what is the average amount of B[a]P in one cigarette.
  • If you divide the mass of B[a]P inhaled in one year by the amount of B[a]P contained in one cigarette, you will find the annual equivalence of cigarettes that you breathe with polluted air.
Kacper Pawlik, MD and Dominik Czernia, PhD
Poland - Cracow
B[a]P concentration
Time spent outside
Total B[a]P inhaled
Cigarette equivalence
The concentration of B[a]P should be less than 1 ng/m³ with reference to the EU Ambient Air Quality Directives.
The concentration of B[a]P should be less than 0.12 ng/m³ to reduce the risk of additional lifetime lung cancer to approximately 1 in 100 000 (World Health Organization).
Attention! In recent years, other permissible concentrations have also been exceeded in this area:
👉 annual of NO₂ - 40 μg/m³, annual concentration was 52 μg/m³
👉 35 times daily of PM₁₀ - 50 μg/m³ per year, 36th highest concentration was 87 μg/m³
👉 annual of PM₂.₅ - 25 μg/m³, annual concentration was 34.3 μg/m³
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