What Is Particulate Matter & Why It Matters Tremendously For Health

 What you don't know CAN indeed kill you.

How do I know? Simple: many people don't know much if anything about the effects particulate matter has on their health.

Heck, I often get the question: "what is particulate matter?!"

This blog post series will explain everything you need to know about this topic.

In this first installment of this 4-part series, I'll explain what particulate matter is and how it affects your physiology. You'll also learn about a few basic statistics that show you why you should take this topic very seriously.

The second part of this series digs deep into the health effects of particulate matter. The third part considers how to measure levels and what air purifier to get. And lastly, the 4th part or installment teaches you 8 additional strategies to lower your exposure levels.

You're probably aware of the deep dives I take into several topics. So, you might have read my series on dopamine, chronic stress, noise pollution, zinc, and self-esteem. This series is similar to the previous ones!

This blog is yet another very detailed breakdown of the science, this time on the topic of particulate matter. Fasten your seatbelts and let's go:



1. Introduction: What Is Particulate Matter?

Particulate matter - a form of air pollution - can be devastating for your health over time.

You may be thinking, however:

"Are you fear mongering again?"

"Another long technical article that takes a long time to read but doesn't offer much practical advise?"

"Air pollution? I can't do anything about that anyway, so why worry? We all die someday, so no need to worry about air quality.

All these questions are misguided.

Let me tell you why:


Why People Misunderstand Health

First of all, yes, I'm fear mongering but I've got good reasons to do so - you'll learn why in a second. Secondly, even though I'm fear mongering I will offer you tons of practical advise to improve your exposure to this air pollutant. And thirdly, your air quality can and will affect the quality of the time you spend here on this planet - reducing exposure will improve health.

So let's get to it and break down the topic of "particulate matter". I'll start with an analogy to understand why this topic can be so counter-intuitive for many people...

That analogy starts with light:

When I'm talking about health, people often think it's very weird that the light in their environment matters for their health.

I've often suggested people to use sunlight or red light therapy for dealing with pain, for example, and yet, some people are unwilling to listen to that advice. 

Keep in mind that I'm not saying you are unwilling to listen to that advice, but please accept that just some people are.

The same is true for wearing blue blocker glasses after sunset: many people are unwilling or unable to believe that light exposure after sunset affects their sleep quality, simply because many "reputable" institutions or television programs don't put out that recommendation.

Air pollution is exactly like light...

Many people already believe that air pollution - specifically "particulate matter" which I'm treating in this blog post - just cannot have enormous health effects. 


Well, if particulate matter exposure did have enormous health effects you'd hear experts talking about the subject all the time, right?

And yet, the opposite is true - particulate matter exposure does have enormous health effects. Simple statistics confirm the often held invalid conclusion that it does not:[2; 4; 206; 216



Particulate Matter (PM) 2.5 

Just one type of particulate matter, called "PM2.5", leads to 800,000 deaths on a worldwide basis every year

In total, 6,4 million years are taken from people's maximum lifespans due to exposure to that "PM2,5". 

Most of that damage actually occur in Asia. 

On a worldwide scale, air pollution--not restricted to particulate matter--caused 4.2 million deaths in 2016.

The problem gets worse:

Billions of people have their lives negatively impacted by air pollution and particulate matter every year. All-in-all, particulate matter is the 13th leading cause of death in the world.


Particulate Matter Analogy

The assumption that air pollution does not affect your health is plain wrong. Particulate matter acts like a slow poison drip that's plugged into your body.

Just imagine that someone adds a tiny bit of poison to your food over time. You won't even be able to perceive that your food tastes differently, because the change is so subtle.

And yet, even though you don't directly perceive more and more poison being added to your body, the damage is still being done. 

Again: am I preaching doom and gloom?

Not at all...

The good news is that air quality is getting better in some regions of the world, such as the US and Europe. The bad news is that pollutants levels are still so high that health problems are still caused by them - and will be caused by them decades down the road.

Phrased differently, the air around you is not improving quickly enough so that you can reasonably expect that we'll have clean air in 10 or 20 years time. You thus have to take matters into your own hands.

a rural area in scandinavia that's free of air pollution
Northern Scandinavia: one of the few places
on the planet without much air pollution...


Do Safe Particulate Matter Exposure Levels Exist?

There's another problem:

The human safety levels of many environmental toxins have gone down over time. An example is that the "safe" levels for lead exposure - a heavy metal - has been going down for decades.

Particulate matter is the same.

Different institutions such as the World Health Organization and the European Union (EU) have different safety standards.

Even though safe exposure levels recommended by these institutions have been coming down, you can't assume that they are currently strict enough. It can thus reasonably be expected that the maximum exposure levels of particulate matter may go down further over time.

Claims actually exist that there are no safe levels of particulate matter exposure. In other words, the more particulate matter enters your body, the worse the health effects will be.

Of course, there's still the elephant in the room: the topic of air pollution is really abstract for many people. 


What Is Particulate Matter: A Definition

Let's, therefore, consider what particulate matter really is - making the topic more concrete to you...

Particle matter air pollution is often called "particle pollution" as well.

Particulate matter consists of small particles that are dangling in the air. Those particles can both be liquid and solid. There are many examples of particulate matter:

  • Smoke from cigarettes or tobacco
  • Dust that can, for example, be emitted as a byproduct of the cement industry
  • "Fly ash", which can be a byproduct of coal energy production
  • "Soot", a black powder that's a byproduct of petroleum or benzene combustion, or "oil smoke".
  • Smog, which you're probably acquainted with.

You get the point...

Just imagine that a tremendous amount of invisible tiny particles are suspended in the air that you breathe every second. 

That pollutant is mostly emitted into the air as a result of our modern lifestyles. 


Different Particulate Matter Sizes

Different types of particulate matter exist, and these types are mainly categorized by size:

The key to understanding particulate matter health effects is to realize these particles are very small.

Yes, really small...

How small?

Particulate matter often has the size of 2.5 millionth of a meter or 10 millionth of a meter. To give you a point of reference, 1 millionth of a meter is a thousand times as small as a millimeter.

Some types of particulate matter, such as smog, may even be of the size of a tenth of a micrometer - 10,000 times as small as a millimeter.

From now on I'll use the term "micrometer" to refer to a millionth of a meter - another commonly used term for "micrometers" is "microns". 

It's not just cars or industry that produce air pollution. Some airborne substances, such as allergens, which trigger people who are allergic to dogs or cats, have roughly have the same size.[7; 8; 9; 10]

Viruses and bacteria are also very small, ranging from a 1/100th of a micrometer to 10 micrometers (which is a huge range, I know...)


Analogy To Understand Particulate matter Size

To give you a frame of reference, let's consider how small particulate matter generally is...

The diameter of 2.5-micrometer particulate matter is 30 times as small as the diameter of a human hair. 2.5 micrometers are unobservable to the human eye.

And keep in mind that 2.5-micrometer particles are still relatively large compared to much even smaller substances such as tobacco smoke and dust, which can both be smaller than 1 micrometer.


Regulation Of Particulate Matter

Because these tiny particles affect your health so thoroughly, institutions try to regulate their expulsion into the air

It's not just particulate matter emissions that are regulated though. Government agencies, such as the Environmental Protection Agency (EPA) in the US, regulate six different airborne chemicals. 

Particulate matter is just one of these chemicals.[16; 17]


(Advanced explanation: the EPA also regulates carbon monoxide (CO), lead (Pb), nitrogen dioxide (NO2), ozone (O3), and sulfur dioxide (SO2).


Oh yeah, you must be thinking about how you are doing regarding these chemicals.

In that case I've got a surprise...

Let's take a quick de-tour:


Guesstimating Your PM Exposure

Before I'll help you understand particulate matter on a much deeper level, please get a general impression of the pollution levels at your location by checking this map.

That map gives you an "air quality index", which is used by many governments to inform their inhabitants about the air quality in their living environment. 

Knowing the air quality status of your environment can bring the problem of air pollution much more alive if you have trouble imagining such tiny particles.

So let's take Paris...

Paris is relatively close to where I'm living and has a huge air quality problem because of the many cars passing through the city.

Just look at the image below:

Visiting Paris will be "romantic", they said...


And the map I mentioned before, that displays worldwide air quality levels, actually reflects what you're seeing on that picture.

As of October 16th, 2018, the moment I'm writing this blog post, the air quality index in Paris is around 24-70.

My place? 

The Eastern part of the Netherlands consistently hits the low 20s and is thus (relatively) safe.

(This blog was originally published a few years ago. Right now I live in Mexico!)

As a point of reference, some areas with an extremely low population density have an air quality index of between 2 and 10 - desolate locations in Sweden or Finland come to mind...

So what's the solution if your location is polluted?


Indoor Versus Outdoor Air Pollutant Levels: Shocking Differences!

If you're thinking "I'll just stay inside to avoid all the pollution" then you're misguided.

Indoor quantities of air pollutants can be ten as high as outdoor.[11] One reason for that distribution is that outdoor air often enters buildings, but many people don't let their indoor air ventilate. 

In other words, air pollutants thus enter many buildings but never exit them. Many modern objects such as furniture also lower the indoor air quality even further.

Indoor air pollution gets more problematic because the average person spends up to 90% of their day inside.[12] Another reason you cannot stay inside all the time is that you'd miss out on sunlight - I consider sunlight essential for health.

Staying inside 24-7 to avoid air pollution is thus not a good health strategy...


The Danger Of PM 2.5 And PM 0.1

But let's go back to the topic of particulate matter. The smaller the size of particles, in general, the more damaging they will be.

Particulate matter with the size of 2.5 micrometers is thus more damaging than particulate matter with the size of 10 micrometers.


Bigger particles are easier to filter larger through the airways - more on that topic later.

So why spend an entire massive blog post on particulate matter alone?

Why don't I talk about air pollution in general?

The main reason for focusing primarily on particulate matter first is that particulate matter is most strongly associated with different diseases of all types of air pollution.

Particulate matter was not always the primary air pollutant though...


History Of Air Pollution

The "Valley Fog" in Meuse, Belgium, in 1930, and "the great smog of London" of 1952 and are notorious air pollution incidents.[13; 14An air pollutant called "sulfur dioxide" was the culprit in these cases...

The Belgian instance led to 60 deaths and thousands of people who became sick--in the English instance, more than 6,000 people died due to the direct and indirect consequences of that air pollution.

The great smog of London was a wake-up call and led to a wave of legislation to reduce air pollution in Western societies.

Air pollution scandals are not restricted to European and North American countries though: the 2013 Harbin smog in China is a more recent notorious air pollution event. In that case, particulate matter was the main culprit.[15] 

Of course, air pollution problems are much older than the 20th century.

Before the 20th century, if you were working in a coal mine you were exposed to horrendous amounts of (particulate matter) pollution. 

Even in pre-history, your ancestors would be temporarily exposed to lots of particulate matter. Camp or forest fires, or the occasional volcano eruptions are examples thereof.


Why Air Pollutants Are A Big Problem!

The problem with particulate matter exposure is not that it is new for humans--the problem is that air pollution has become omnipresent and (almost) inescapable.

So what's the solution?

Simple: read this full blog post series!

I'll tell you everything you need to know to reduce your risks and reclaim your health - it's going to be a somewhat long ride, but in the end, you'll learn how you can cut your expose levels by 50-90%.

In the next section, I'll lay the groundwork and tell you explain what different types of particulate matter exist...


Advanced explanation: if you've been reading my blog you know that I'm very keen on giving definitions at the beginning of articles, so that I'm sure you and I are talking about the same thing when you're reading my articles. In the case of air pollution, it's more difficult to give strict definitions because hundreds of chemicals are subsumed in the air.

A few of these chemicals, such as particulate matter, tropospheric ozone, and sulfur dioxide, act as a benchmark for air pollutants in general. It's impossible to measure all air pollutants in existence because there are thousands if not tens of thousands of possible categories. Air pollutant levels also fluctuate throughout the year and are specific to locations, and there's no one size fits all measurement that can be generalized, either spatially or temporally.




2. Different Types Of Particulate Matter PM2.5, PM10.0, And PM0.1

Understanding the different types of particulate matter is important because not all types have the same health consequences.

Remember that particulate matter can consist of both solid and liquid particles that are suspended into the air. Particulate matter can actually consist of hundreds of diverging chemical elements.

For that reason there's no "one size fits all" approach to understanding how particular matter is chemically made up.

The size of these particles is another story - size is easier to standardize. It's important to understand how the particulate matter scale works.


How The PM Scale Works

The particulate matter scale exclusively considers the size of particles and not their chemical constituents. Sizes of particles are expressed as PM10, PM2.5, and PM0.1.

Let me explain...

  • PM10 contains particles with sizes smaller than 10 micrometers. In other words, PM10 contains particles between 0 and 10 micrometers in size (nerds: diameter)
  • PM2.5 contains all particles with sizes smaller than 2.5 micrometers, and thus, all particles with the size of 0 to 2.5 micrometers.
  • PM0.1, lastly, are the really small particles that, you guessed it, have a diameter of up to 0.1 micrometers. 


PM10 also includes the particles that are contained within the PM2.5 and PM0.1 categories because of the way the scale is built up.

In the EU, for example, 70% of all PM10 particles are actually PM2.5 particles,.[28] Phrased different, only 30% of PM10 particles have a diameter of 2.5 to 10 micrometers.

As a logical consequence of how the scale is built up, PM2.5 also contains all PM0.1 particles because PM2.5 contains all particles smaller than 2.5 micrometers, and thus also PM0.1 sized particles as well.

You get the drill...


Different Particulate Matter Names

Different types of particulate matter go by the following names:

  • PM10 is called "coarse"
  • PM2.5 is called "fine"
  • PM0.1 is called "ultrafine"

That was simple: all you need to know about size. 

Let's now consider why most inhabited places of this planet are engulfed with clouds of particulate matter. 

Particulate matter can be formed in several ways. Let's explore these ways:


How Particulate Matter Is Created

The first way is when particulate matter is formed as a direct byproduct from fuel usage, industry, or other environmental sources - this type is called "primary particulate matter".

Examples of primary particulate matter are combustion by several types of engines (including petrol and diesel), or using coal or biomass for energy creation.

"Primary particulate matter" can also form as a result of slow damage that occurs to infrastructure over time, such as roads, and as a byproduct several industries.

If you're a metalworker, for example, certain chemical compounds such as nickel, lead, and arsenic can be emitted into the air and can eventually end up in your body. The creation of cement or mining are examples industrial processes creating particulate matter pollution.

Even indoor cooking and heating can create particulate matter - which frequently occurs in developing countries. 

Wood combustion in residential areas is also a frequent source of primary particulate matter pollution.

Interesting fact: cars don't just put off particulate matter through their emissions - using your brakes, for example, can also emit chemicals into the air from your tires and brake mechanism.

Yes, that toxic stuff is everywhere...

traffic as a main cause of air pollution
Campfires: avoid standing in the smoke to reduce
the negative health effects...

Natural Sources Of Particulate Matter

Nevertheless, deserts and volcanoes are also natural sources of particulate matter. Not all particulate matter is thus created by human beings. Deserts, for example, can supply lots of dust that's carried through the air for very long distances.

For that reason, desert areas such as Saharan Africa, locations around Saudi Arabia and regions in central Asia end up with very high particulate matter concentrations.

But there's yet another particulate matter source:


Secondary Particulate Matter

The second way particulate matter is formed is due to chemical reactions in the atmosphere - called "secondary particulate matter".

Examples are gasses that are emitted as a by-process of energy creation which can result in the formation of particulate matter in the air. Gases emitted by traffic are another example.

Humans are the main reason why secondary particulate matter exists.

Because the air is nowadays being filled with gases and particles, chemical reactions in the air create additional chemical configurations that results in new particulate matter.

But let's go back to the different sizes of particles: PM10, PM2.5, and PM0.1

What happens with these particles once they're emitted?


How Far Different Types Of Particulate Matter Travel

The smaller the particle, the longer particles stay suspended in the air. Smaller particles can thus travel longer distances.

Particles close to 10 micrometers (PM10), for example, can travel up to 20-30 miles and (generally) stay in the air for a few hours.

Smaller particles below the 2.5 micrometers size (PM2.5), on the contrary, can stay in the air for weeks and travel for hundreds of miles. PM2.5 can even cross continents and oceans...

Bigger is thus not better (in this regard)...


(Advanced Explanation: I know the Aristotelian thesis that heavier objects react differently to gravity than lighter ones has been solidly debunked since Galileo. The issue with the travel distance of particles, however, does not have to do with gravity but with air resistance. To give an analogy: a feather, due to its low weight, is easily affected by air resistance, while cannonballs are not. PM10 is, therefore, less easily affected by air resistance than PM2.5 or PM0.1.)


Particulate Matter Bigger Than PM10

Now, you might be thinking: "what about particles that are larger than 10 micrometers?"

Great question.

Such particles are not regulated because in that case, governments would have to start regulating the sand that's emitted into the air. Larger particles also have fewer health effects, and regulation is therefore not that necessary.

But let's move to another topic:

In addition to the size of the particles, institutions also measure how many particles are subsumed in the air and their weight:


Deeper Explanation Of Measurement

Let's thus consider in what metric the air's particulate matter levels are measured.

The levels of particulate matter are measured in micrograms per cubic meter. A cubic meter is a three-dimensional area with a length, width, height of one meter.

You can have a particulate matter concentration of 2 micrograms per cubic meter (m3), for example, or a level of 35 micrograms per m3

More micrograms per mgenerally entail that you're breathing in more particles. And more particulate matter subsumed in the air means you'll experience worse health consequences.

To minimize the negative health effects, institutions all over the world have developed guidelines on how much particulate matter are allowed to be contained in the air.


How Institutions Understand PM2.5 and PM10

Let's explore maximum PM2.5 and PM10 levels set by different institutions.[18; 19; 20; 21; 22; 23]

In the US, the Environmental Protection Agency (EPA) has set following maximal exposure levels:

  • Sourced from primary PM2.5, you're allowed to have an annualized average of 12 micrograms per m3 exposure level.
  • From secondary PM2.5 sources (chemical reactions in the air), the maximum level is located at 15 micrograms per m- averaged over the year.
  • The combined level of primary and secondary exposure is located at 35 micrograms per m3.
  • PM10 levels may not exceed 150 micrograms per m3 on a 24-hour basis for more than once per year. In other words, if you're exposed to a 160 and 180 micrograms level of PM10 per m3 on two different days in a single year, you've exceeded the EPA's safety levels.

How about the EU? As always, the EU has somewhat stricter qua environmental policies compared to the US:

  • The combined primary and secondary exposure to PM2.5 is located at 25 micrograms per m(as opposed to 35 in the US). That number is averaged over a year.
  • On a 24-hour basis, maximum PM10 levels may not exceed 50 micrograms per m(merely a third of the maximum US threshold). The annualized average of PM10 exposure may not exceed 40 micrograms per m3.

 Then there's the WHO. The WHO is even more strict:

  • Maximal PM2.5 exposure levels are just 10 micrograms per m3, on an annual average, while the 24-hour maximum is located at 25 micrograms per m3.
  • For PM10, the annualized maximum average exposure level is 20 micrograms per m3, while the 24-hour maximum exposure level is 50 micrograms per m3.

Please observe that the WHO's averaged PM2.5 exposure standard is three times as strict as US policy.

There's a problem though...

Even if you're living in a Western European country - these countries are often considered "clean" on a worldwide basis - you won't get close to these WHO-mandated maximum exposure standards.[28] 

the WHO guidelines on air pollution
Paris: clean but not so clean...


Your health is thus almost certainly affected by particulate matter no matter where you live unless you're living on the North pole or Amazonian rain forest... 


Why You Cannot Rely On Governments To Keep You Safe From Air Pollution

Don't be fooled by the thresholds of governments and health institutions: even your location matches these standards, you're still not safe.

Let me explain:

Even if you're exposed to an average of 5 micrograms per m3 on annual basis your health is still being damaged, even though you're only exposed to half the particulate matter the WHO recommends as a maximum.

How about a 2.5 micrograms per mexposure level?

In that case, the damage will be less than when you get exposed to 5 micrograms per m3, but your health is still damaged.[28]

Simply put: less particulate matter exposure is always better. There's no known safe exposure level.

Less is more...

The next step in my argument is to understand how particulate matter works in your body. By understanding how particulate matter ends up there, you can easier imagine why it was such widespread health effects...



Finishing Thoughts: You Better Start Caring About Your Particulate Matter Exposure!


You get it now!

Particulate matter is usually a large influence on your overall health. If you're living in a polluted environment, it becomes much harder to simply stay healthy.

That's why, in the second installment that's published soon we'll dig deeper into the topic of proven scientific health effects of particulate matter. If the statistics I showed you today, such as 800,000 direct deaths due to particulate matter, scared you today, next installment will be even scarier!

Don't worry though, the night is darkest before the dawn. 

The third and fourth installments give you options on how to reduce your exposure by 90-99%. Everyone can control their exposure, believe it or not. 

You can too.

Stay with me and keep reading... 


This is a post by Bart Wolbers. Bart finished degrees in Physical Therapy (B), Philosophy (BA and MA), Philosophy of Science and Technology (MS - with distinction), and Clinical Health Science (MS), and is currently a health consultant at Alexfergus.com. 


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