Air Quality 101

Why is air quality important?

Most people are unaware of both the quality of the air they breathe and the consequences of breathing polluted air. Actually, as many as 9 out of 10 people live in places with unsafe air – and they are not only in China or in large cities. Poor air quality causes respiratory diseases, heart diseases and stroke, as well as cancer. More than 7 million people die every year because of air pollution. In this short Air quality 101, we will explain air quality and how pollution and pollen impact the health and well-being of you and your family. Most people are also unaware of when they are most exposed and what can be done to improve the quality of the air they breathe. If you would know that the quality of the air you breathe is harmful and what makes it harmful, there are often simple measures available to reduce the risks for you and our family. Did you for instance know that riding a car or a bus in a polluted city is worse than walking outside? For sources and more detail, please see https://airmine.ai/air-pollution-kills-and-costs/.

What do the air quality levels mean?

Good PM2.5: 0-12 μg/m3 Safe and healthy air. Open windows, enjoy outdoor activities.
Moderate PM2.5: 13-35 μg/m3 Moderate pollution.  Can affect sensitive people. Sensitive people should consider reducing hard physical activities outside
Unhealthy for sensitive PM2.5: 36-55 μg/m3 Unhealthy air for sensitive people. Sensitive pople (asthmatic, children, elderly, people with heart diseases and respiratory diseases) should limit physical activities.
Unhealthy PM2.5: 56-150 μg/m3 Unhealthy air!  Sensitive people should avoid physical activities. Everyone else should limit physical activities. 
Very unhealthy PM2.5: 151-250 μg/m3 Very unhealthy air!  Sensitive people should avoid outdoors, everyone else should limit outdoor time.
Hazardous PM2.5: 251- 500 μg/m3 Dangerous air!  Remain indoors.

Seen other numbers in other apps?

There are quite a number of air quality indices (AQIs) in use. We have chosen to display PM2.5 particle levels as these particles are the most harmful. We use μg/m3 (microgram per cubic meter air) as unit. For an overview of air indices, please see Wikipedia – Air Quality Index.

The different pollutants

Particulate matter (PM)

PM stands for particulate matter (also called particle pollution), followed by a number indicating the size of the particles in micrometre (μm). These fine particles come from various sources, both natural and man-made, examples are dust, pollen and soot.


Very small particles. PM2.5 are all particles smaller than 2,5 μm in diameter. For comparison, a human hair has a diameter between 50-70 μm. Typical sources are wood fires, sand storms, power plants and exhaust from cars. PM2.5 particles are dangerous precisely because they are so small. They are light and stay long in the air and can penetrate deep into our lungs and slip into our bloodstream. PM2.5 particles can cause heart and lung diseases. They are known to trigger or worsen respiratory diseases like asthma and bronchitis.


Small particles. PM10 are all particles smaller than 10 μm in diameter. Major sources of PM10 are dust from road traffic and burning of fossil fuels and wood. Agriculture also produces PM10.  Exposure to high concentrations of PM10 can result in a number of health impacts ranging from coughing and wheezing to asthma attacks and bronchitis to high blood pressure, heart attack and stroke.


Ultrafine or nanoparticles. All particles smaller than 0,1 μm in diameter. Major sources for PM0.1 outdoors are diesel exhaust, power production and residential heating. Indoors contributors are typically paint pigments, tobacco smoke, heating and cooking. PM0.1 are harder to measure, they are so small that they are transported deep into our respiratory systems. They can stay in our lungs or in our blood for months, and and cause damage. UFP risk assessment research is still in the very early stages.  


Sulfur dioxide. SO2 is an invisible gas with a nasty smell. Most of the sulfur dioxide in the air comes from the burning of fossil fuels by power plants and other industrial facilities. Sulfur dioxide affects human health when it is breathed in. It irritates the nose, throat, and airways to cause coughing, shortness of breath, or a tight feeling around the chest. The effects of sulfur dioxide are felt very quickly, typically 10-15 minutes after breathing it in. People with asthma or similar conditions are most at risk from developing symptoms from sulfur dioxide.


Nitrogen dioxide. NO2 is part of a group of gases called nitrogen oxides (NOx). Nitrogen dioxide gets in the air from emissions from cars and power plants. Breathing air with a high concentration of NO2 can irritate our respiratory system. Exposure can aggravate respiratory diseases, particularly asthma. NO2 along with other NOx  reacts with other chemicals in the air to form both particulate matter and ozone. 


Carbon monoxide. CO is a colourless and odorless gas. Main sources are motor vehicle (car) exhaust and other burning of fossil fuels. High carbon monoxide levels can be harmful to people as it blocks the amount of oxygen transported in our bloodstream. High concentrations of CO is primarily a problem indoors, but CO levels outdoors can be high in developing countries.


Ozone. We are here concerned with ground-level ozone (ozone in the stratosphere protects the earth from harmful UV-radiation). Ground-level ozone is a secondary pollutant, meaning it is not directly emitted. It is produced when gases like CO and NOx react. Ground-level ozone is a major health risk, linked to asthma and respiratory diseases.


Volatile organic compounds. There are a lot of various VOCs, both man-made and naturally occuring. Some VOCs are dangerous to our health, like benzene from car exhaust. Indoors VOCs can be released from paint and building materials. Breathing VOCs can irritate the eyes, nose and throat and can cause difficulty breathing and nausea. Some VOCs can damage the central nervous system or cause cancer.  

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Pollen is a plant’s male DNA that is transported to the female part of the flower to enable the plant to reproduce. This is obviously useful, but a lot of people get allergic reactions from the small plant parts. The immune system mistakenly identifies harmless pollen as a dangerous intruder and begins to produce chemicals to fight against the pollen. Pollen allergy typically causes one of more of these symptoms:  Runny nose, sneezing itching in eyes/mouth, stuffy nose (nasal congestion) or swelling around the eyes. Pollen allergies can be diagnosed by doctors and there are several good medications available. The pollen season varies from pollen type to pollen type, and hits at different times in different locations. Pollen spread by the wind. Rain will often stop the pollen from flying around. Some common pollen types people are allergic to:

  • Grass (gramineae or poaceae)
  • Ragweed (ambrosia)
  • Mugwort (artemisia)
  • Birch (betula)
  • Alder (alnus glutinosa)
  • Hazel (alnus serrulata)
  • Willow (salix)
  • Olive (olea)
  • Cypress (Cupressus)
  • Oak (quercus)

Read more:

Who should take extra care – sensitive and vulnerable persons

For people with asthma, pollen allergies or other respiratory diseases, air quality matters even more. These diseases are triggered and worsened by poor air quality.  Children, elderly and people with lung or heart disease are also in the sensitive group and should take extra care to avoid exposure to air pollution.

How does the weather play in?

Weather conditions impact the levels of both pollen and air pollution. Topography will often also play a role. Air quality will often be lower in valleys than in the higher area around. Wind will disperse particulate matter and other pollutants and often give better air quality. On the other hand, if the wind blows polluted air in your direction it does not help! Rain or snow will normally help clear the air and give better air quality. The weather can trigger asthma symptoms. Cold, dry air is a common asthma trigger, as well as hot and humid weather. Thunderstorms may give asthma outbreaks and wind affects some asthmatic people. 

Read more:

How about indoor air quality?

Most of us spend most of our time indoors. Respiratory issues (sneezing, coughing) and symptoms like a runny nose and eyes may stem from particles like mite, dust and volatile gases.  Major sources of indoor pollution are 

  • House dust
  • Burning fuels (heating, fireplace, candles)
  • Volatile gases released from paint and building materials
  • Mold and mite
  • Tobacco smoke
  • Pets
  • Radon gas (from the ground)

The best way to prevent indoor pollution is to eliminate or control the source of the pollutants. The next step is proper ventilation to remove any pollutants that do enter.  It can be worth following some simple advice to improve indoor air quality: Keep your house clean (including your furniture and pets). Change your air filters. Turn on your kitchen ventilator when cooking and don’t be afraid to open windows to let fresh air in (given that the outdoor air quality is good). In the developing world, household air pollution is one of the leading causes of disease and premature death. Burning fuels such as dung, wood and coal in inefficient stoves or open fireplaces for cooking is the main source of the poor air quality.

Read more:

What can you do?

Know your air!

Stay informed about air quality where you live. Use a reliable source to get current air quality values and forecasts. Consider investing in an indoor air quality sensor/monitor if you are worried or uncertain about the air quality in your home, as well as an air purifier.

Find out what you react to.

Track your symptoms if you have any, and compare them with what and how much you breathe.

Seek medical advice!

Health professionals should be contacted if in doubt. They can help diagnose and provide appropriate treatment.

If outdoor air quality is poor: Be wise when you plan your day.

Can you stay inside during the worst hours? Avoid hard physical efforts on days with poor air quality. If you have to go out, choose smart routes: Avoid high-traffic areas and leave your car! You are better off outside a car than inside. Walk or ride your bicycle.

To improve indoor air quality:

Keep your house clean, including upholstered furniture and your pets. Change your air filters. Turn on your kitchen ventilator when cooking and don’t be afraid to open windows to let fresh air in (given that the outdoor air quality is good!).

Make your voice heard!

Get involved in local initiatives and help your community improve air quality!


When to expect birch pollen in Norway?

Hazel and alder is flowering in Southern Norway, but the key allergen to many of us is birch. When can we expect the birch pollen season to start?

Spring in Europe – alder, hazel and birch pollen

We are heading into warmer and lighter days in Europe, lockdowns or not. And no surprise, the pollen is faithfully here.

Green in India means red in Norway

We've attempted to compare the different PM2.5 breakpoints in selected air quality indices. It turns out a green level does not mean the same around the world.

EU’s clean air outlook – saving lives and reducing costs

EU has launched its Second Clean Air Outlook report. There are both premature deaths and money to be saved by improving the air quality.

Pilot testing our air quality monitor – where is the pollution coming from?

We are pilot testing our air quality monitors and have started to dig into the first results. We had expected local variations in PM-levels, but it turns out the source is probably found far away from the neighbour's wood burning stove.

Air quality in Europe – it’s going the right way

EEA's recent report gives hope for the air quality in Europe. Most pollutants have been reduced the last decade, but Eastern Europe is still heavily affected.

Winter is coming – with polluted air

As we enter the colder months on the northern hemisphere, air pollution levels rise. Much of Europe is affected, but can hardly match the soaring levels in Northern India.

Smoke from west? No, dust from east

Did the huge forest fires on the US West Coast in September impact air quality in Europe? Not really, the measurements show. What did have an impact, was dust transported by winds from south east.

Better air in Beijing than San Francisco

Last week, you'd rather breathe Delhi air than take a stroll in San Francisco. Smoke and ashes from the huge forest make air quality on the US West Coast the worst in the world.

Air pollution shortens more lives than smoking, drugs and malaria

Although we are in the midst of a global pandemic, air pollution remains the single major contributor to loss in life expectancy across the globe.

Has air quality improved during lockdowns?

Delhi has had much cleaner air during the Covid-19 lockdowns, whereas we do not find the same improvement in PM2.5 levels in Oslo, Norway.

Birch pollen – how did it develop?

The birch season is over for this year - we have dived into our data and created a visualisation of how it developed in Europe.

Grass pollen levels still high in Central Europe

High levels in Denmark, Germany and Poland, France may have seen the peak. Grass pollen in UK and Scandinavia is on the rise as northern Europe really warms up.

Monitoring Air Pollution With Airmine’s Air Quality Index API

Learn how to use our Air Quality API in this short tutorial. The API is designed for web, IoT, and mobile app developers. It is a free API that gives you access to the PM2.5 concentration at any given location, both current concentration and a 8-days forecast.

Grass blooming in Central Europe

The grass season is long - and Central Europe is in the midst of the blooming. Northern Europe is starting to feel the season.