Effects of Air Pollution on Human Health

What is your initial reaction when you come across a car that emits a lot of smoke fumes?

For many of us, it is to cover our mouths and noses with a handkerchief, or at least our hands. Because if we don’t, we are aware that the coughing fits we can get if we inhale that smoke is only a minor consequence.

You know that this emission coming from vehicles is just one of the contributors to air pollution, but what you may not be aware of are its other sources, with some of them being even more hazardous than vehicle emissions.

And because of these different sources, it can be expected that there will also be various effects human health.

It is important that you be informed with both the sources and its effects, as well as other necessary information about it. Prevention is indeed better than cure, and the best way to prevent the health effects is to understand what causes it in the first place.

blue sky

What is it?

Everyone knows that air pollution exists, but not all of them are aware of what it really is. Most people think that it only involves the dark smoke from vehicles and factories, especially smog, but they are unaware that it goes beyond that. It is one of those concepts that people think they are very much familiar with, only to discover that they still have much to learn about.

Ideally, the air in the atmosphere should contain mostly nitrogen, some oxygen, and a little bit of a mix of other trace gases to be considered completely clean and healthy for us to breathe in. But with air pollution, the essential nitrogen and oxygen are lessened, and harmful pollutants in the air increase at the same time. Because of this, the air quality is compromised.

Since these pollutants present also have toxic chemicals or compounds, air pollution is detrimental not just to humans but also to the environment, including plants and animals alike. And unlike what most people think, it is present both indoors and outdoors and in both urban and rural areas.

And because air easily circulates, it can also easily transfer to and affect other areas.


There is a lot of misconception about air pollution, that is why it is important to know the most important facts about it, including the reasons why this environmental issue should be taken seriously by everyone.

  • It is due to multiple sources and not just the smoke coming from cars. The most dangerous ones are those that are invisible to the naked eye.
  • This type is considered more dangerous than other forms because of the pollutants involved. Being mostly invisible means that we are constantly exposed to them without our notice. Also, they generally contain toxic substances.
  • The amount produced annually is believed to be greater than the total amount of water, ground, and land pollutants.
  • These particles can cover large distances, with scientists finding out that air pollution coming from Asia has been affecting the western region of the US for the past two decades.
  • In a recent report, China and India were discovered to be collectively responsible for more than half of the deaths worldwide due to air pollution.
  • Exposure can have various effects on anyone, from a simple cough or eye irritation to lung cancer.

girl wearing mask

  • It happens both indoors and outdoors.
  • Urban areas generally have the worst air quality due to the amount of traffic present.
  • The US only ranks 10th worldwide in terms of having the best air quality. And among its states, California has consistently topped the list of states with the worst air quality in the entire US.
  • It indirectly affects the global economy, with the loss amounting to billions of dollars on average. Productivity is lessened because of illnesses and death related to this problem, which results in loss of income for companies.
  • Certain types not only worsen air pollution but also exacerbate other global problems, like climate change
  • It has long been considered as responsible for claiming so many lives each year, but it is now considered as the 4th leading cause of death worldwide
  • While occurring both indoors and outdoors, indoor types are generally considered as more dangerous, as it is more concentrated
  • More people die from a stroke caused by air pollution, followed by heart disease and cancer and lung diseases

To sum it up, it has become a worldwide problem affecting not just us humans, and it is not caused by a single factor. And unless we continue to find ways to address this problem, it is bound to get worse.

What Causes It?

You may be aware that there are different causes, but you will be surprised to know that the most common ones you can think of are not the only ones. There are also other sources that you are probably not aware of, especially those that are invisible to the naked eye.

It happens due to the excessive amounts of pollutants present, which are composed of mainly gases, liquid aerosols, and solid particles, that the environment is unable to absorb or break down. They are those that are not always present in the atmosphere and are also mostly invisible.

The sources, in general, can either be man-made, also called anthropogenic, or naturally-occurring. But with air pollution, the main cause is attributed to anthropogenic causes.


Any activity that involves the use or burning of fossil fuels is seen as the biggest culprit. Because industrial processes use up the largest amount of fossil fuels, they are considered as the major cause of the problem. At the forefront of these is facilities and equipment that generate power, such as power plants, especially those that use coal.

Other industrial causes include:

  • Emission coming from production and manufacturing facilities, like factories and other industrial plants
  • Mining activities, like drilling, blasting, and extracting
  • Facilities that produce chemical products and metals
  • Diesel generators
  • Plastic manufacturers and facilities that process them
  • Gas and oil refineries
  • Smelting
  • Industrial heating devices that require fossil fuel
  • Waste incineration and use of landfills

vintage generator


Not a lot of people know that certain household activities also contribute to air pollution, particularly those that also involve the use of fossil fuels, as well as the use of household products.

Did you know that you also release pollutants while you cook, with the amount depending on your heating source? Whether you use electricity, gas, or wood, these sources will contribute in your home because they can produce formaldehyde, carbon monoxide, and other problematic particles. The cooking ingredients themselves may also release problematic particles as they are heated.

When you use the following household products, certain problematic particles are also released:

  • Solvents
  • Cleaning products, especially disinfectants
  • Air fresheners
  • Laundry products
  • Paint
  • Glue and other chemical adhesives
  • Personal care products, such as deodorant sprays and hairsprays
  • Tobacco products, such as cigarettes
  • Pest or insect sprays

Home construction or renovation is also known to contribute because of the materials involved. Old homes are even more dangerous to work with, as they may possibly release lead (can’t recall if there is an article about lead in the check4lead website, but it can be linked here) and asbestos, which are also known pollutants, during construction work.


Another major cause is the transport sector, especially those that emit carbon dioxide. As you know, cars are also one of the major sources because of their exhaust fumes, with diesel-powered cars known to be the biggest culprit of vehicle emissions. While the bigger trains and planes also use fossil fuel, it is the smaller cars that pollute the air the most because these cars greatly outnumber other modes of transport, which means they collectively use up more fossil fuel.


The agriculture industry is also known to contribute to air pollution, and it has been discovered to be the biggest contributor. Most of the particles come from the use of various agricultural products like fertilizers and pesticides, especially those that contain ammonia. Not only that, various farm equipment also use fossil fuels in their operations. Crop dusting and burning is also another farming activity known to release problematic particles.

Natural Causes

While natural causes have less of an impact, they still add to the overall probæem. Some of them may be preventable, while others occur instantaneously and give us no chance to prevent them.

Among the natural causes are:

  • Volcanic eruptions
  • Radioactive decay
  • Decomposition of plants and other organic matter
  • Forest fires
  • Whirlwinds
  • Dust and sand storms
  • Mold
  • Pollen and other natural allergens
  • Animal droppings
  • Wind erosion
  • Sea-salt spray
  • Animal digestion that produces methane, particularly involving cattle
  • Plants that produce volatile organic compounds
  • Hot springs
  • Fog and mist
  • Soot
  • Certain gases, such as ozone and radon
  • Release of gas due to natural processes

While man-made causes are known to produce more air pollutants than natural ones, both of them contribute to the overall problem every day.

What is the Biggest Source?

You may have noticed that we mentioned fossil fuels plenty of times in the previous section, so it should come as no surprise that the biggest source of the problem, in general, is any activity that involves its combustion.

People are not aware that plenty of our daily activities involve the use of these fossil fuels, directly or indirectly, and this has detrimental consequences to the environment, especially when left unchecked.

In particular, the biggest source is our use of automobiles. Transportation not only uses up a lot of fossil fuels, but it also disturbs pollutants on the ground that can easily become airborne, such as road dust. Also, cars are responsible for both primary and secondary sources.

Cars are considered as a primary source of toxic gases and particles. While other means of transport also produce these particles, cars vastly outnumber their volume, which is why they collectively produce the most pollutants. Some of these will react with other particles, or even themselves, resulting in the formation of secondary pollutants like ozone, acid rain, and smog.

Primary air pollutants that are emitted by cars, as well as other modes of transport, are:

Because most of them are coming from cars, due to the burning of fossil fuels, different car manufacturers have been trying to cut back on its use. This is why they are now developing cars that are more eco-friendly, such as hybrid and electric cars, in hopes of lessening their contribution.

Different Types

Most people have no clue that there are different types , namely indoors and outdoors. They believe that air pollution only happens outdoors where all the smog is present, and staying inside a confined space, like their home, protects them from all the particles.

criteria pollutants Outdoor Indoor
Carbon monoxide Cigarette smoke Building materials
Ground-level ozone Ground-level ozone Cooking
Lead Particulate matter Gases
Nitrogen Dioxide Smog Household and personal care products
Particulate matter Toxic gases Tobacco smoke
Sulfur Dioxide   Various allergens

Why air pollution is not limited outdoors has to do with the different types present. And if you recall, these can either be primary or secondary, which means they may be pollutants themselves, and at the same time be responsible for the creation of other air pollutants. W

The EPA has identified the following as the “criteria pollutants” or those that are most common in the United States:

  • Ground-level ozone
  • Lead
  • Particulate matter
  • Nitrogen Dioxide
  • Sulfur Dioxide
  • Carbon monoxide

sign saying no science, no coffee

Aside from these six common variants, the agency has also identified 187 hazardous air pollutants that are being monitored through the Clean Air Act. All these can easily be transferred from one place to another, and their minuscule sizes means they can easily pass through the smallest of gaps.

You already know that activities that involve burning fossil fuels are the major source, with the use of cars being at the forefront. In fact, it is generally responsible for most of the air pollutants. Most of these activities are done outdoors, that is why we get the highest amounts of exposure when outside. And if you recall, most of the causes are also found outdoors.

Aside from most of the natural and man-made causes we mentioned earlier, outdoor air pollution also includes the following:

  • Cigarette smoke
  • Particulate matter produced from activities involving burning
  • Toxic gases, especially those produced by industrial processes and facilities
  • Ground-level ozone
  • Smog

What makes outdoor air pollution the most familiar to most people is the fact that it is associated with smog. This is the most visible sign and is formed by reactions between various pollutants. Because smog appears in the form of a dark haze or cloud, people immediately make the association. This visibility of smog makes people aware of the problem outside.

On the other hand, smog does not form inside any house or building, letting people think that there is no such thing as indoor air issues. After all, the sources seem to be less than that of outdoor air ones, and any visible smoke inside the house, such as due to cooking, is not seen as air pollution but simply a nuisance that will disappear in a few.

Sources of indoor air problems, which are mostly due to indoor activities, include:

  • Building materials
  • Household and personal care products and chemicals
  • Gases
  • Various allergens found indoors and outdoors, such as mold, pollen, pest droppings, and fungal spores
  • Tobacco smoke
  • Cooking

However, this does not mean that you should not take the indoor air quality seriously. While it may be smaller in volume, it is more concentrated than outdoor air pollution, which makes it more dangerous. This happens because air ventilation is poorer indoors than outdoors, preventing the problematic particles from moving around freely, which leads to them to have a higher buildup indoors. And because we spend most of our time indoors, we get more exposure.

Clearly, these two types pose different dangers, with higher amounts for outdoor exposure and higher concentrations for indoor exposure. Exposure to any of these two types is dangerous, and it is even more amplified by the fact that most of them are invisible to the naked eye, which makes it a challenge.

PM2.5 Pollution

People tend to associate smog with air pollution the most, not knowing that there is a much more hazardous enemy in the form of PM2.5. Particulate matter comes in two general categories, PM10 and PM2.5, but the latter is considered more dangerous. In fact, scientists agree that it is the most lethal among air pollutants.

Also called fine particles, PM2.5 is named as such because of its size, measuring only 2.5 microns or less. To put it into perspective, the average strand of human hair has a diameter of 50 to 70 microns, which means you need an electron microscope to see PM2.5. Because of its size and weight, it remains airborne longer and anyone can get exposed to it much easier and at higher amounts.

PM2.5 is produced through combustion of any kind. Since the burning of fossil fuels is known to be the biggest contributor to the problem, it means PM2.5 is also abundant in the atmosphere. And since they can also react to other air pollutants, they can produce even more dangerous compounds.

All these characteristics make every one at risk of PM2.5 pollution. What makes it even worse is that when inhaled, the particles are so small that they immediately penetrate the lungs and settle there, leading to all sorts of illnesses. Not only that, but they can also affect soil and water quality, which can compromise our food supply.

Because of all these, various government agencies are now keeping a closer eye on PM2.5 more than any other air pollutants. The Air Quality Index (AQI) now also measures the amount of PM2.5 present, together with PM10.

What are the Effects on Human Health?

Everyone knows that it has various effects on the human health, but many of them are not aware that these are more just coughing fits. Anyone can get exposed to these harmful particles, but there is no one more vulnerable to it than the children and the elderly.

Children spend the most time outdoors where the exposure is abundant. And because they are still small, their bodies are not yet fully equipped to handle these particles, as they are still in the development stage. They also get exposed to ground-level particles more than adults, especially those that are emitted by cars.

The elderly are also among the most vulnerable, but only next to children. While their bodies can defend themselves better against these particles, age plays a factor; the older the adults are, the less capable they are to handle the exposure and other environmental hazards. And if they already have pre-existing conditions, it can increase the symptoms they experience or aggravate their conditions.

Some of the health effects anyone can possibly experience or acquire due to exposure to air pollution include:

  • Eye, nose, and throat irritation
  • Lethargy, weakness, or constant fatigue
  • Issues with the reproductive organs
  • Damage to the cardiovascular system, including the hardening of arteries, increased risk of stroke and heart attacks, left ventricular hypertrophy (LFV), hypertension
  • Diabetes
  • Allergic reactions
  • Various respiratory diseases, including asthma, pneumonia, emphysema, chronic bronchitis, chronic obstructive pulmonary disease (COPD)
  • Mobility issues
  • Mental health issues, such as anxiety, dementia, schizophrenia, behavioral changes, lower IQ levels, and depression
  • Headaches
  • Liver and spleen damage
  • Blood-related issues, like anemia
  • Premature birth, miscarriage, low birth weight, compromised fetal growth, and the child possibly having autism (when exposure happens while pregnant)
  • Nausea
  • Compromised development of the nervous and respiratory systems in children
  • Different types of cancer
  • Tightness of chest or chest pains
  • Skin issues
  • Weaker immune system
  • Irregular heartbeat
  • Wheezing and coughing
  • Lung issues, like decreased lung function, damage and scarring, loss of lung capacity
  • Osteoporosis

You may have noticed that many of these health issues are not related to the respiratory system, which is contrary to what most people would expect. This just proves how dangerous it is, with death being its worst consequence.

How Does It Affect the Environment?

It not only affects humans but also the environment, and how it does so mainly has to do with the pollutants present. These can either cause different harmful environmental conditions or worsen existing ones, just like how it affects health.

Air pollution is seen as the cause of the following environmental hazards and effects:

  • Acid rain – is due to sulfur dioxide and nitrogen oxides that cause a reaction with various chemicals and compounds in the atmosphere. Acid rain can fall not only as rain but also snow and fog and can damage vegetation, as well as affect water quality by making it acidic and harmful to aquatic life and those who drink from it
  • Damage to crops and forest – it can directly cause damage to vegetation, not just acid rain. Ground-level ozone, in particular, can affect the growth and yield of plants and even reduce their lifespans because it can make them more susceptible to pests and diseases
  • Harm to wildlife – just like humans, wildlife can also acquire all sorts of health problems due to air pollution, such as reproductive issues, birth defects, and various diseases
  • Eutrophication – nitrogen and phosphorus from various sources will promote harmful algal bloom that can kill off marine life
  • Haze – just like smog, haze is a form of fog but is made up of particles that remain suspended in the air and block sunlight, affecting visibility

Aside from causing the above conditions, it is also known to contribute to global warming and ozone layer depletion (add link to ozone layer depletion article). The greenhouse gases are attributed to global warming, and certain particles are also considered as ozone-depleting substances.

When it affects the environment, humans are also affected. The plants and animals we consider as our food supply may be lessened or compromised because of air pollution. And if we consume animals that have ate and drank contaminated plants and water, this contamination may also affect us.

What are the Global Effects?

Because the pollutants can easily travel once airborne, the effects can be felt globally. The issue in one country may be blown away to another country, which means the problem in one country can worsen due to it moving from another country.

Unfortunately, those in developing countries are the most affected because they use more fossil fuels than developed countries, particularly when cooking and heating their homes. These countries also have many of the world’s industrial facilities and engage in agricultural activities the most, which exacerbates their problem.

Most of those on the top 50 list of cities with the world’s worst air pollution, particularly in terms of PM2.5, belong to only these countries: India, Pakistan, Bangladesh, and China. These countries are also known as the hub of the world’s industrial facilities, that is why they are expectedly on the top of the list of countries with the highest annual concentrations of PM2.5. Bangladesh, Pakistan, and India are the top three countries, while China is now in 12th place, which is a vast improvement.

The top 10 countries with the highest PM2.5 concentrations are:

  1. Bangladesh
  2. Pakistan
  3. India
  4. Afghanistan
  5. Bahrain
  6. Mongolia
  7. Kuwait
  8. Nepal
  9. United Arab Emirates
  10. Nigeria

While these countries are known to have poor air quality due to the PM2.5 concentrations present, the majority of all the countries worldwide exceed the global standards set. This is the reason why the whole world seems to experience its effects.

By now, you are aware of the numerous health effects on humans and why it is becoming one of the leading causes of death worldwide. The WHO even reports that more than 7 million people die annually due to both indoor and outdoor air particles, with most of these deaths occurring in developing countries in Asia and Africa. This number does not include those who acquired symptoms and illnesses and survived, which is expected to be higher.

Climate change has become a global issue in recent times, with its effects felt all over the world. Unbeknownst to many, air pollution and climate change are closely linked to each other, as the pollutants can cause various reactions in the atmosphere that directly affect temperatures. Climate change is associated with greenhouse gases. By lessening the sources, climate change is also reduced.

This scenario also applies to the depletion of the ozone layer. The hole in the ozone layer gets bigger with the increase of ozone-depleting substances that get released in the atmosphere. Many of these compounds that cause the depletion are also known problematic particles, such as volatile organic compounds and hydrochlorofluorocarbons. If these are lessened, ozone layer depletion is also lessened.

The environmental effects mentioned earlier is also felt in various parts of the world, especially acid rain that resulted in the deaths of vegetation and marine life. Because the pollutants needed to produce it can travel long distances by wind, acid rain can happen anywhere. One example is the fact that Norway experiences acid rain that is due to pollutants coming from the United Kingdom.

The widespread reach, including its effects, has been a cause of global concern for years now. While there have been signs of improvement in terms of air quality in some countries, the consensus is that there is still much to be done. To solve this, different countries have made their own legislations and they also adapted universal policies to follow, such as through the UN Sustainable Development Goals and the Geneva Convention.

Lessening the global effects is still a work in progress, but we are slowly starting to see improvements that affect everyone.


To better understand the seriousness of the problem, here are other important statistics you need to know:

  • More than 90% of the people worldwide, or 9 out of 10, are now living in places with poor air quality that exceed the standards of the World Health Organization
  • As many as two billion children are believed to be severely exposed to outdoor air pollution. And in 2016, 600,000 children reportedly died due to acute lower respiratory infections.
  • 1 out of 10 children under the age of 5 years old died because of illnesses.
  • In the US, as many as 11 million people are residing in counties where the air quality also fails to meet the national standards
  • In 1952, the problem in London was so bad that almost all modes of transportation had to be stopped and people were unable to see their own feet while walking. This incident, which lasted five days, became known as the Great Smog of London of 1952 and was responsible for thousands of deaths that are said to range from a total of 4,000 to 10,000.
  • Around 800 people per hour or 13 people per minute die because of it. This means 1 out of 8 or a total of 7 million lives are now lost annually, with almost all of these deaths happening in developing countries.
  • Out of the 7 million average premature deaths, 4 million is due to outdoor air pollution and 3 million is due to indoor air issues.
  • People breathe in an average of 20,000 liters a day. Just imagine the exposure you inhale, depending on where you live.
  • Crop production has also been affected by it. As much as 50 million tons worth of yield is lost annually.

All these figures are enough to alarm not just scientists but also world leaders to move quickly and come up with ways to address the problem. With numerous legislations and calls to action over the years, we are now reaping its benefits. The best proof of this is the improving overall condition of air quality throughout the world.

The world has come a long way if we were to compare the figures now to those in the past before any kind of intervention occurred. However, the battle is not yet won and millions of people are still dying because of it every year.

How to Reduce It

Surprisingly, it does not require fancy machinery nor a lot of resources to reduce air the issue. For most people, they are not even aware that the simplest measures really do go a long way when it comes to dealing with this problem.

And if you are wondering how you can be part of the solution, here are some of the best ways for you to do so:

  • Cut back on your use of anything that requires power and switch off electrical appliances and equipment, as well as lights, that are not in use. Conserving energy means fewer fossil fuels are needed to produce the needed energy.
  • Use appliances with an Energy Star label, as they are confirmed to use power more efficiently. Also, consider installing alternative energy sources, such as solar panels
  • Go places using mass transport, biking, or simply walking.
  • Make sure that your car, boat, and any other engine-powered machinery are regularly maintained to prevent fuel spills, ensure fuel efficiency, and prevent tailpipe smoke from coming out. Overweight cars and tires in poor condition will also cause an increase in fuel combustion
  • Refuel during the evening because the temperature is cooler and will lessen the number of pollutants that can be produced. This principle also applies to the use of any gas-powered equipment, such as those for gardening
  • If possible, switch to eco-friendly or hybrid cars and equipment, especially those that are manually-powered
  • Choose paints, cleaners, and other personal and household product that are labeled environment-safe, especially those that have little to no VOC present
  • Avoid idling your car for long periods
  • Ideally, use household appliances and equipment, such as washing machines and dishwashers, only with a full load to conserve electricity
  • Instead of doing backyard burning for biodegradable material, create a compost pit or mulch them
  • Lessen your use of wood, whether in cooking, heating, or any other activities that require it to be burned
  • Ensure that your household products are properly sealed, especially those that contain VOCs, to prevent these compounds from evaporating
  • When driving, stay within speed limits to lessen fuel combustion. The faster your car runs, the more fuel is needed and the more particles are released
  • Have a garden and grow plants that are known to purify the air
  • Stop smoking, whether indoors or outdoors
  • Participate in local initiatives

You may be familiar with many of these tips, but you may not be aware of the impact these small changes can bring to the entire world. If we all do our share, there is a 100% guarantee of good results that everyone will benefit from.

But since having zero air pollution is not going to happen anytime soon, you should also ensure that you minimize your exposure to it at the same time, especially on days when the AQI levels are forecasted to be high.

Here are some of the ways you can keep yourself protected to avoid experiencing its health effects:

  • Keep yourself updated with the AQI to learn when the levels are forecasted to be elevated
  • Avoid staying outdoors and doing intensive physical activities during the times when levels are high, as well as near roads, highways, and any other location with a lot of traffic
  • If exposure is inevitable, wear face masks, particularly those with an N95 or P100 rating
  • Cover your mouth and nose when dealing with smoke, even those coming from cigarettes, if a suitable mask is unavailable.
  • Install air purifiers in your home, especially those that are capable of filtering even the smallest PM2.5 particulates. You can also place purifying plants to help improve indoor air quality.
  • Ensure proper ventilation by installing air vents and exhaust systems in your home, especially in the kitchen and bathrooms, and adding filters that can block air pollution.
  • Air out your home every now and then to prevent pollutants from settling and to lessen the concentration present. it is advisable to do it between 3 to 5 pm when the PM2.5 levels are generally lowest
  • Remove any mold and mildew present

Doing these measures will not just protect you, but it will also help lessen the levels present. That way, the time when we will all constantly breathe in clean air may happen sooner than later.

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