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Indoor Air Pollution: All the Things You Should Know

A surprising fact, the indoor air can even be more polluted than the air outside as it cannot dilute anywhere.

If you feel more suffocated when staying inside than when out.

You usually struggle with a sore throat or cough, then the air quality inside your house is very poor.

So, what exactly pollutes the air?

This post, we’ll walk you through groups of pollutants that are most common.

Without further ado, let’s get started.

Why is Indoor Air Pollution Important?

We spend about 90% of time staying indoors, so indoor air pollution affects our health quality deeply. 

In addition, breathing is the activity we do the most in our life. We breathe about 20.000 times per day, which makes this the easiest way for harmful  irritants to enter our bodies.

Breathing low air quality is killing your health day by day. Meanwhile, the air you inhale always has bacteria and airborne pollutants, more or less. 

According to the EPA, every year, on average, house pollution affects more than 25 million people, and 7 million are children and infants.

Though recent year results show a decrease in air pollution. Still, air quality needs to be put on top of our consideration.

Outdoor Pollution Affects Indoor Air Quality?

Indoor air pollution is a lot related to our way of living and house hygiene.

But if you are living in a high-polluted city or near the pollution areas, the polluted air surrounding can dilute into your house easily. Combining with already-had pollutants, it worsens your home air quality badly.

Some of the most common outdoor air pollutants and harmful gas the scientist suggest are:

  • Particulate Matter
  • Ozone
  • Wild smoke
  • Asbestos
  • Radon
  • Lead

If you live in or near high population concentration areas, finding effective ways to cure the air is necessary. And our first thing to do is to dig in information about these irritants.

5. Outdoor Pollutants

Modernization opened a new future to humankind, but on the other hand, it also brought up many environmental problems that we have never faced throughout history.

Just air pollution alone affects millions of people on earth. As WHO estimated, air pollution kills approximately seven million people each year.

And these pollutants are to most to be responsible:

PM (Particulate Matter)

Particulate matter (PM) is a mixture of solid particles and liquid in the air. They are dust, dirt, soot, or smoke and exist in various sizes, from visible to microscopic that can’t be seen by naked eyes.

This is one of the most common pollutants that, according to scientists, is the top factor causing respiratory diseases, especially these two kinds:

  • PM10: an inhalable particle that is 10 micrometers or smaller.
  • PM2.5: Also known as fine dust, incredibly tiny at 2.5 microns or smaller. It is 30 times smaller compared to human hair.

Particulate matter is the leading cause of air pollution. It is ubiquitous and comes from many sources. Some typical sources are car exhaust, dust, particles from burning wood, forest, etc.

Fine dust shouldn’t be underestimated. Due to its small size, it can travel to your body by inhaling. Then, it is absorbed into your lungs and bloodstream, causing countless problems and health hazards.

Hence, finding ways to reduce fine dust is every home’s urgency, and it happens that these methods can easily be done.

The Effective Solution You Need

The fastest and easiest way is to use an air purifier. A True HEPA air purifier can capture particles as small as 0.3 microns. Many machines can even catch 0.1 microns particles. So the machine can effectively filter fine dust.

In fact, we suggest that air purifiers are one product that every home must-have, especially city households. This machine is the shortest way to help with the air problems in your home and save you from many preventable illnesses.

If interested, you can find some of the greatest air purifiers for dust here. With our guidance and review, you can find the most suitable product for your house condition.

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Ozone is a colorless gas that affects humans in both ways – good and bad. The beneficial ozone is in the upper atmosphere , which called stratospheric ozone. It protects us from UV light and sun radiation.

Meanwhile, ground-level ozone, also known as tropospheric ozone, causes us many health problems, and this is what we will discuss in this part.

Where Does Ground-level Ozone Come From?

Ground-level ozone is born by chemical reactions between oxides of nitrogen, volatile organic compounds (VOC), and sunlight.

Pollutants in the reaction can originate from cars when exhausting, electric utilities, wildfire smoke, power plants, industrial boilers, oil and gas extraction, etc.

Ozone can worsen respiratory disease and causes many other health problems if inhaled in a long time.

High ozone levels usually happen in the environment around us. In the US, several states even form year-round ozone season, which are California, Florida, New Mexico, Hawai, as the EPA data.

Notably, ozone level is denser on hot sunny days. The city experiences the condition more severely as it has heavier traffic and exhaust from electronics.

Ozone can move a long distance with the help of wind. So the rural areas near the city can also influence high ozone levels.

How to Know When the Ozone Level is High?

Still, there are no handle-measuring ozone tools for households.. Ozone level is estimated by a whole specific system. To get the number, scientists use many instruments, such as ground-based machines, balloons, satellites, aircraft, rockets, etc.

This result will be presented on the government’s website, where you can get the measurements. Air now is one website you can trust.

If the ozone level exceeds the safe limit, the air is not healthy to breathe. Hence it is crucial to find protection methods. When it comes to this issue, can an Air Purifier work?

Can Air Purifiers Reduce Ozone?

Up to this point, it is said to have no practical method to remove ozone completely from indoor air.

HEPA air purifiers, in fact, make no changes in ozone levels. On the other hand, many UV-C light and Ionizer air purifiers even slightly generate unsafe amounts of ozone to your home.

Meanwhile, air purifiers with PECO technology are tested to successfully reduce ozone level. However it can only filter part of the amount that exists in the air.

The best way to deal with the unhealthy ozone in the house is to keep the air clean and well-ventilated. By that, ozone gas won’t stay still in your house following the circulated air to the outside.

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Asbestos refers to a group of six naturally occurring presently in the environment in the form of soft and flexible fibers. This substance is resistant to heat, fire, and corrosion.

Due to the stability, asbestos can make the object stronger. Hence, it is widely used to make various kinds of products.

Up to today, more than 3,000 types of asbestos-containing products have been created and used in many majors, such as industries, marine, construction, and car manufacturing.

Asbestos products can be present in your house as it has in the component made up the products, for example cloth, plastic products, paper, hairdryers, roofing, interior decoration, paints, adhesives, plastics, etc.

Despite these advantages, their hard-to-dissolve feature makes them exceptionally toxic to our health. When it comes inside your body, it stays in there and accumulates through time, and can cause cancer.

When it becomes airborne, this substance is easily inhaled. So, to protect ourselves from this harmful substance, we need to notice some fundamental rule.

Ways to Deal With Asbestos

How can we avoid asbestos harm? How can we know if the asbestos rate in our house is dense or not?

Honestly, it is hard to define if our house is influenced by asbestos without taking a professional test. You can know if a product contains these substances or not on its label. But if it doesn’t have it, the only way to know is to have a test.

Typically, the products will release asbestos when it is too old and being disturbed. So try not to disturb them, or if it is necessary, you should cover the item when fixing so the asbestos dust won’t spread out.

In addition, you should buy products with non-harmful asbestos. And by that, you have got something about one health-harmful contaminant. Next, we will jump to Radon – another alarming harmful gas.

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If you haven’t known, Radon is a colorless, odorless, tasteless radioactive gas from the ground, soil, and rocks. These sources are of natural origin. However, man-made construction can also produce Radon.

According to the EPA, it is the second biggest reason that leads to lung cancer. If you get Radon poison, it won’t show any apparent effect until it causes cellular change, leading to lung cancer.

Radon from outdoors exists in a trace amount, people take bad effects of it mostly when indoors. Why can Radon exist indoors while it originates from nature? Here is why:

How can Radon get into our home?

Radon gas finds its way through the cavities, crack on the wall, floor, gaps around pipes, and the water supply (notably from the well).

When traveling in the air, it can stick to the surfaces of the objects. Those objects can be anything, even air particulates, and water surfaces.

Radon concentration is denser in areas close to the ground, such as the basement. It can concentrate and remain for 4 days in the area, simultaneously affect to our body during that time. Therefore, we need to know the way to detect Radon for the sake of our health.

How can we identify Radon?
Indoor air pollution can be even more serious than outdoor. As we spend about 90 percent of our time inside, this becomes an urgent issue. Let’s name some common irritants on top of the concern.

Radon cannot be detected by human senses, so you need to get Radon estimation through a lab test or purchase one Radon measuring kit, which is inexpensive.

When it comes to Radon estimation, you can take a short-term or long-term test. Short term result is only valid for 2-4 days, which takes a shorter testingtime.

Long-term results can be used for 90 days or up to one year. However, it takes a longer testing time, and this particular kit will cost you more.

Radon is estimated by picocuries per liter or pCi/L. To a particular extent, Radon is considered hazardous when:

  • Over 4 pCi/L: Concerned as high Radon level and highly be a health hazard.
  • From 2 pCi/L – 4 pCi/L: This is under the dangerous rate, but it is still not safe. It can cause some health risks, on a lesser level.
  • Below 1 pCi/L: To protect yourselves as much as possible from Radon, you should keep the Radon low at 1 pCi/L.
Ways to Reduce Radon

Reducing the source of Radon isn’t easy work. It needs professional technique and skill to do so.

This job relates tightly to the house structure. So unless you are skilled and well-trained, you shouldn’t do the job by yourself.

Here are what you can do:

  • Hire a qualified mitigation contractor who is well-trained to install the radon reducing system
  • Sealing cracks on the foundation to prevent the entry of Radon
  • Increase ventilation in the house naturally by opening the door and windows.
  • Installing heat recovery ventilation (HRV) can significantly help to reduce Radon.

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Lead is a type of metal that can be found in all parts of the environment. Due to its benefits, people now apply lead in a wide variety of products.

You can find lead in building materials, lead-based painting, cosmetics, batteries, ceramic, pipes, and even water.

Lead can be released in the air by industrial activity. This is also the reason to explain the high lead concentration near mining and smelting sites.

The Health Effect of Lead

Lead makes its way into our body in these 4 basic ways:

Because of its serious consequences, lead-based products were banned from being manufactured in the US in 1978. Still, there are many products with lead composition (with a small amount), here are some of the most common ones:

  • Toys: Many inexpensive toys are found to have lead contaminants. Children usually put toys in their mouths, so it is crucial for parents to choose safe toys for them.
  • Cosmetics: As lead helps make-up layers to last longer, eyelash, lipstick, and other types of cosmetics commonly contain lead contaminants. This is proved to be one of the leading sources of lead poison. 
  • Ceramic and pottery products: Utensils made from ceramic and pottery that are imported from other countries, like China, are often found to have lead. Lead from these appliances can directly pass on the food and enter our body when we eat.
  • Drinking water: Water from natural sources all contain lead. Drinking water from the well can directly introduce lead to your body. Water from the faucets can also have lead because the corrosion of the pipe with lead base can release lead particles.
  • Food can: Cans with lead components were banned in the US in 1995, but solder lead from other countries can contain lead.

These solder leads can be the side seams and the silver-gray solder. Through time, lead can pass on the food contained inside. Acidic food and open lead will fasten this process.

Ways to Protect Yourselves from Lead

By getting rid of the source of lead, you can reduce tremendously lead contaminants in your house, here are what you can do:

  • Avoid products with lead contaminant
  • Fixing chipped or peeling paint
  • Test water for lead and reduce lead in water by flushing the tap for one or two minutes before using
  • Use lead-free food containers
  • Prevent children from playing on soil

Reducing lead is straightforward and doesn’t need much effort. Meanwhile, the next pollutant will be harder to solve, but we will find a way through it. This time, ozone.

Indoor Air Pollution: What’s in the Indoor Air?

For better engagement, we classify these pollutants into 5 groups. The first group gathers some most common irritants in our house.

1. Biological Contaminants

Biological contaminants can source from living creatures and plants. They can also be living organisms themselves.

They come in various sizes, ranging from visible to invisible to our sight.

Though originates from many sources, in general, biological contaminants needs these factors to thrive:

In our house, these biological contaminants focus the most in:

  • Areas with dampness, wetness such as bathroom, kitchen, basement, pipe system, etc.
  • Damp objects such as draperies, carpet, rug
  • Areas filled with dust such as the arctic, under the bedding, wardrobe, cooling system

Water is the source of life of all creatures on earth, and this contaminant is no exception. Two over three of the ideal environments are related to high humidity.

Indeed, humidity is one key factor contributing to the building up of harmful organisms. Exceeding or too low humidity both cause unhealthy air problems.

By that we just get the picture about biological contaminants in general. 

Now let’s focus in more details on each kind of biological contaminant, which includes:

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Virus & Bacteria 

Viruses and bacteria are always in your house, no matter how well you do the house hygiene. They are known as bioaerosols.

Though many kinds of viruses and bacteria are beneficial, many can directly cause human, animal, and pet illness or disease.

Here is something about their characteristics. Viruses are much smaller than bacteria. They fall between 0.02 μm and 0.5 μm in size while bacteria are between 0.5 μm and 5 μm.

Most of the virus and bacteria are born from the outside environment.

According to NCBI research, the concentration of bioaerosols outdoors is higher than indoors, from 1.6 to 2.6 times.

However, when it comes to our house, these are places where viruses and bacteria are mostly found.

The kitchen – According to The NSF, the “hot pot” of bacteria and viruses lies in the kitchen. Why is that?

In a regular family, research shows the kitchen has some utensils that contain a large percentage of fecal virus and bacteria. On the dish sponge was up to 75%, much higher than the bathroom faucet.

Coming next in the list of top bacteria-host utensils are:

  • The chopping board
  • The sink
  • The faucet hand
  • The countertop

Bathroom – Many people will jump to the conclusion that the toilet has the highest germ concentration. But studies of an organization show different results.

Among these top-bacteria-influencing items, Show curtain surprisingly be the one to have bacteria the most.

  • Shower Curtain
  • Shower Floor
  • Toothbrush handle
  • Toilet Seat
  • Faucet Handle
  • Interior door handle

Human – Surprising that areas exposed to human hands and activity contain a large number of bacteria and viruses. 

Scientists have reported that humans carry at least 3200 bacterias on the surface body and about 150 species just on the hands alone.

As mentioned, viruses and bacteria are born mainly from the outside. However, they can get inside through humans and pets.

If they meet the suitable conditions, they will spread and thrive in our house.

Bacteria and viruses are unavoidable. To protect yourself, doing exercise and taking healthy food to raise the immune system is the most effective way.

Combining this with good house hygiene, which should be done on a regular basis, will protect you well from the potential diseases.

Next, we will figure out another common microorganism that is typically born in high humidity and moisture conditions – mold & spore.

Mold & Spore

Wonder what mold and spore are? You should look to the wall corner near a water source or on objects close to water. Seeing black arrays on them? Those are mold and spores.

Mold, mildew is actually a part of fungi’s kingdom. They are visible when growing on things such as:

Spores are seeds that are sent from mold when they fully build up. 

Spores cannot be seen by eyes. When emitted to the air they will keep traveling until landing on the surface.

Though this microorganism plays an important role in the natural world, when it exists in your house, it mostly does harm.

The Cause of Mold and Spore?

The main factor that is responsible for mold and spores building up is high moisture, or exceeding humidity.

Many data have shown that they grow when the humidity reaches 60%.

They also need ideal temperature and sunlight to grow. Despite this fact, some can still grow in low-temperature conditions. Just look at what happens to a sandwich left in the fridge for days.

If met with the necessary nutrients (moisture, water, food, etc.), it only takes 1 to 2 days for  mold spores to build up. The process time differs at different house areas based on diverse conditions.

Also, after the rain, the soil that absorbs water can remain wet for hours. That’s why the footer part of the house usually has a chunk of thriving mold. 

When mold gets what it needs to develop, it will go through these phases that can easily be recognized:

Developing Phases of Mold and Spore

When meeting ideal conditions, mold forms into visual dark chunks.  

They thrive and when fully grown, spread their spores to the air. Signs of this phase is that you can sense musty odor, which is also when mold impacts our health the most.

When landing on the surface and meeting the environment they need, spores will start the circle life.

The Harm of Mold and Spore?

First of all, mold damages the objects they stick on, making them downgrading or even unable to fix.

If you step into a place with fungi clinging to the wall, you and everyone else must think that “this place is really old and filthy”? And if someone buys a house, absolutely, they won’t choose the one full of musty mold.

Mold in a large degree can damage the house forever

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Second, mold has an unbearable smell. If you are sensitive to smell, you will feel very irritated or even intolerable.

And if you experience bad health issues, you probably inhaled in the spore for a long time. In more detail, exposure to them can exacerbate respiratory syndrome or cause allergy.

According to the EPA, about 4.6 million cases of asthma are attributed to dampness and mold in the house. And this is just asthma alone.

Thus, you will need effective methods to solve the mold, and air purifiers for mold are one straightforward way to escape.

Aside from mold and spores, pollen also causes health hazards to a large number of people, which we will discuss more in the next part.


Flowers and plants play an essential role to both humans and nature, but to those who are allergic to pollen, it becomes a health torturer.

Pollen is a plant production existing in powdery, granular form and serves fertilization purposes. At a particular time of the year, vegetation releases pollen.

Regions filled with a particular type of plants produce pollen at the same period of time in high concentration.

This causes health symptoms to pollen-allergic patients, called seasonal and regional diseases (such as allergy, sneezing, respiratory disease) or hay fever.

Living in the countryside or where it is rich in vegetation, there’s a time in the year, the smell of plants becomes really heavy.

To many pollen-allergic folk, this is their nightmare. Symptoms of hay fever are what they periodically have to suffer.

Biểu đồ người bị hay fever (nếu có)

According to the National Health Interview Survey (NHIS) data in 2018, the number of people diagnosed with hay fever a year is 19,2 million, making up 7.7% of the total country population.

When is the Hay Fever?

Most plant fertilization takes place during warm and sunny months, which is no doubt Spring and Summer. In particular, from March to September is the golden time of the blooming season and is also the peak period of hay fever.

In the USA, there are some common types of plants that are said to be the top plants causing allergy, according to an organization:

Season of plants cause allergy

Hay fever can last for weeks or even months until the blooming season ends.

You can track the hay fever season through this website to prepare for prevention. It is updated daily and will show the pollen count (the pollen density in the air) and inform you of the plants that cause allergies in the region. And then, we will go for a prevention method.

How to Protect Yourself from Pollen

There is no way to keep yourself completely safe from pollen when going outside. What you can do is to limit or reduce the time exposed outdoors. 

When inside, you can actually control the situation. Choosing an air purifier for allergy to eliminate the airborne pollen in your house is the most effective way to solve this issue.

Aside from plants, animals are also a common source causing the allergy. And this is most related to our most close-knit friends – cat and dog.

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Pet Dander

Adorable pets to many people are mental support, joy in life, and a true family member.

However, when it comes to health issues, do you prepare well to protect yourself from the potentially bad effects pets cause?

How Can Pets Cause Allergies?

Any animal with fur can cause pets allergies, but this symptom is most associated with dogs and cats.

We also need to get this clear, pets themselves do not cause allergies, our body reacts to the protein in their urine, salvia and dander (dead skin cells).

Pets’ fur is not an allergen. However, they indirectly cause allergy when carry allergens, like pollen, and urine, dander.

Pet’s allergens are hard to dissolve, they sustain in your house for a really long time and gather most in places like:

What are the Bad Effects a Pet can Cause?

First of all, pets are one of the big reasons for allergies and respiratory diseases, such as asthma.

According to the NCBI, 10% – 20% of people in the world experience pet allergies, and more than 13 million people in the USA have allergic asthma. One of the main sources is pet dander.

Aside from this, we, especially the pet owners, cannot deny that a pet’s fur and smell are real problems for house hygiene.

Despite how much you try to clean the fur today, the other day, it just goes back to the same as before. We got to do something about it. Let’s find some solutions to these issues.


In addition, to help you with the allergens, an air purifier for pets is what you should purchase. You can find more detail in our top-rated product review.

Looks like that it needs a lot of work. Lucky that dealing with the following pollutants won’t take you much effort, be relieved!

Dust Mites, Insects

Dust mite is a very small insect-like pest which is only ⅓ – ¼ millimeters long, and is hard to detect through naked eyes. 

Dust mites live in high moisture, warm environments. They exist largely on bedding, mattresses, carpets, curtains, and upholstered furniture, etc.

Though being a type of insect, don’t worry; they don’t bite, sting, or parasite on us. 

Their food Organic matter including human and animal dead skin shed. The water they need is taken from the humidity in the air.

So if you get an itching rash after a night’s sleep on the mattress and there is nothing like mosquitoes bite, there must be some kind of insects that did this, definitely not dust mites.

How Dust Mites Do Harm to Our Health?

So how can they damage our health while they don’t bite at all?  Our body responds to the allergen they produce, which are their fecal pellets and debris.

These substances are also very small and can become airborne contaminants easily.

Problems with dust mites, in fact, are more popular than we think. According to an organization, four out of five households in America are detected to have dust mites in at least one bed, let alone the other places.

To reduce the possibility that dust mites cause, you can actually do some actions.

Ways to Prevent Dust Mite?

Preventing dust mites allergy doesn’t take a lot of effort. It only needs careful hygiene:

  • Wash the bedding weekly and, if possible, in hot water
  • Vacuum the house regularly
  • Keep the humidity at a healthy rate (from 30-50 degrees)
  • Clean the floor and furniture with a damp cloth

Other than this, you can use some support from the machine to improve the situation. We have some recommended air purifiers for you.

Next, we will come to another notorious air pollutant responsible for the lethal disease, it’s smoke.

2. Smoke

Smoke from Wildfires

Smoke is one of the leading factors that cause severe pollution in both outdoor and indoor.

It is a mixture of particles and chemicals resulting in the burning of a variety of sources, notably carbon-based material.

Smoke contains many substances, and these three are the most notable: carbon monoxide, carbon dioxide, and particulate matter.

On daily life, these sources of smoke is met the most:

Smoke Produced when Cooking

Cooking smoke is exhausted from the burning food and material used to make fire (coal, wood, etc.) As we cook every day, we are exposed to smoke from cooking daily.

In city houses, people use gas or electric cookers, which doesn’t create much smoke. Though there still food smell remains, the range hood will greatly help you deal with it.

Nevertheless, in remote areas or in the countryside, especially in Asia countries, people mainly use charcoal, heating wood, dung, leaves, grass to cook (these are called biomass fuel).

This produces carbon dioxide and can maintain in the house for hours, directly lowering indoor air quality contemporarily.

WHO (World Health Organization) reported that smoke from biomass fuels harms at least 3.8 million people around the globe and affects children’s breathing.

Meanwhile, the next type of smoke harms far more than this number, also which we have heard a lot – secondhand smoke.

Secondhand Smoke – The Top Killer

Secondhand smoke is smoke emitted from burning cigarettes or exhaled by smokers. Compared to other kinds, secondhand smoke ranks first in damaging health.

It contains hundreds of toxic chemicals that affect both smokers and non-smoker.

The danger is it accumulates in the body and only shows signs when it damages the organ badly.

Every year, the number of deaths in America contributed by secondhand smoke reaches 40.000 cases, affecting more than 300.000 children and infants with respiratory disease, according to the American Lung Association.

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Smoke from Burning Plastic

Plastic is sourced from oil. When burning, it generates a pungent odor that is extremely bad for your health.

When burned up, smoke from plastic emits substances that are said to cause forever damage to people who inhaled, including dioxins, furans, mercury, and polychlorinated biphenyls (also known as PCBs).

As we don’t burn plastic in our house for sure, the plastic smell mostly comes from outside. However, the smoke can get into your home if you live near the burning ground.

Plastic products exist everywhere around us, from utensils to big house appliances such as tables, bicycles, etc.

Among them, there is one environmentally polluting plastic product that we overuse: plastic bags.

How Plastic Bags Harm Us?

Plastic bags, if not burned, would take thousands of years to dissolve. Meanwhile, we consume millions of plastic bags every day.

Most of the waste plastic bags will end up burned in the dump yard. 40% of the world’s garbage ends up burning, and 12% of it is plastic.

Plastic bags emit a large amount of toxic contaminants. Among them, Dioxin is the most prominent to discuss.

These substances travel in the air in particles from and landing on ground. If it falls down food-growing vegetation, it will stick to the plant. And finally enter our body when we eat that plant.

Eating plants with dioxin contaminants can cause cancer and lethal disease. As the usage of plastic bags is still maintained, the amount of toxins from plastic is still a worry.

Wildfire Smoke

The last type of smoke on our list and is also the most fierce one is wildfire smoke.

Wildfire smoke originates from burning vegetation, spreads uncontrollably in a vast land, and forms columns of smoke that can travel for thousands of miles.

This horrific disaster can be sparked through lighting, scorching temperatures, or just by a burning cigarette that is thrown away unconsciously.

It can be very severe, substantially impact the whole earth ecosystem, as a witness in some record-breaking fire forest events in 2020.

How Bad Can Wildfire be?

Smoke from wildfires deteriorates tremendously. The smoke caused by wildfire contains PM2.5 dust (also known as fine dust), which causes considerable damage to the nasal system and contributes to cancer.

The research estimated that in 2019, there were more than 4.5 million people in the USA who are highly affected by wildfires, both property, and health.

If you live in an area near a wildfire, the air quality outdoors around your house is not healthy to breathe. This air can access your home through the door, window, or air vent and stay in there.

If this situation happens to you, you can purchase a HEPA air purifier to reduce the problem.

In addition, you should also identify areas that usually get wildfires to see if you are near them or not. Follow this fire and smoke map to track the event of wildfires in the USA daily.

Aside from smoke, odor is also a worth-to-notice air pollutant that you shouldn’t underestimate. We’ll see the reasons below.

3. Odor

Odor is a bad, unhealthy smell that can originate from anything, they can be highly toxic or simply bad-smell. Here we classify them into three group:


VOCs (the full form is Volatile Organic Compounds) consists of a group of toxic odors that come under a gas emitted from solid or liquid.

It has a harsh smell that is most related to a brand new car, painting, or wooden furniture.

VOCs are widely used to produce household devices. Many of the products are appliances you see and use every day, such as:

Among all, paints are best-known to release VOCs the most. It is used to make the paint dry longer.

And by that it also takes quite a time to dry all out when applied to the wall and release gas during that time.

That’s why new houses often have a very harsh smell, and it could last for a month until all the odor runs out.

In the VOCs world, formaldehyde is the most mentioned.


Formaldehyde is the most common part of the VOCs world. It is both a natural and man-made substance. Chemical-based formaldehyde is widely used as a component in products made of wood.

For more particular, it is added in the adhesives, which help the wood to stick tighter. The typical material that has this chemical is particleboard, hardwood plywood, and MDF (medium-density fiberboard).

Products made of these kinds of wood are present in many wood furniture we often use in the house. For example, the working desk, chair, cupboard, wardrobe, the open door, bed, sofa, etc.

Formaldehyde affects the user’s health on the nasal system. However, many manufacturers still use formaldehyde because of the low cost and material-saving.

Instead of chopping the whole tree, they can reuse or use the milled wood to make a new item that is high-quality and long-lasting.

Will VOCs Exist for Long?

When brand new furniture first comes out of the box, they carry a heavy and harsh smell that our nose can obviously detect. As VOCs are unstable, their smell can last for days to years.

It also depends on the boiling point of the object, which means that at a certain temperature (maybe really low or high), the VOCs odor will be heavier.

There is no way to protect yourself completely from VOCs. Instead, we can only reduce its influence to a rate that is still fine when breathing in. Here is something you can do:

  • Ventilate the house well
  • Using HEPA Air Purifier for Odors
  • Avoid buying furniture with harmful VOCs rate
  • Wash, clean the appliances regularly

Besides VOCs, there is another common chemical substance that affects our health as bad as what VOCs does, and the next part will tell more about it.

Pesticide and Cleaning Chemical

Pesticide and some cleaning chemicals, though made with good purposes, the harsh odor emitting from them is something bothersome.

Most of us still think these chemicals only cause bad health issues when our skin or body is exposed regularly and directly to them.

However, for people who are sensitive to smell or are allergic to chemicals, especially children, pesticide and chemical odor can bring up some harmful health effects.

If you are sensitive to smell or even if you are totally normal and well-being, come out of your garden after the pesticide spray, you might get then a little dizzy and have a sore throat.

Meanwhile, there are some places and objects in our home that often emit a bad nasty smell. Let’s name what they are.

Irritating Smell from Places and Things

There are odors that are harmless to our health but still driving us crazy because of being too smelly. Though the smelly thing could be anything but they are most gather in these places in the house:


The kitchen can be the dirtiest and smelly place in our home, especially on these appliances:

  • Dish-washing sink
  • Refrigerator
  • The Stove
  • Garbage Disposal

These are appliances haunted with food smells every day while we don’t clean them.

Especially the dish-washing sink. It is usually exposed to water, developing mold and spores’ host, which carry bad odor and disease.

The refrigerator is often haunted with a heavy food smell. The smell of garlic, jackfruit, raw meat, and cooked food mixed together in the fridge can literally make you faint.

So when storing these foods, wrap them in a plastic food sealer or put them in a closed food box. You can also use some food with scent to keep your fridge smelling good, such as acidic fruit. A few drops of vanilla extract to a sponge, cotton, can also improve the situation.


Bathrooms will be the second range of most smelly places in the home. And the toilet is like one scabby sheep that is enough to spoil the whole flock.

But when it comes to this issue, we now have many options to reject the toilet odor, such as using toilet cleaning chemicals, burning candles with scent, or using a spray with fumes, etc.

Aside from these, you should also need to keep the bathroom and the towel dry. Make sure to ventilate the room well to get rid of the smell stuck inside.


Mudroom is where we often store shoes and outerwear, umbrellas, etc. Sometimes these objects are left wet to dry after exposure to water. This directly builds up the stinking smell right at the open door.

Getting rid of the smell of the mudroom is straightforward. You only need to clean them regularly and try out the wet, damp object under the sun.

4. Inappropriate Humidity

Humidity affects directly how you feel whether hot or cold. Inappropriate humidity will make you feel very uncomfortable.

Aside from this effect, humidity is also the key factor leading to the build up of microbiological contaminants, which can cause us some health issues.

So it is important to keep the humidity at a healthy and comfortable rate. To know it, a humidity measurement is necessary.

You can use these measuring devices to get the result within seconds:

  •  The digital hygrometer
  •  An Analog Hygrometer

Humidity unit is percentage (%). There are limits which presents comfortable or unhealthy moisture level:

  • Under 25%: Poor humidity level. The air is too dry, you might experience skin irritation, dry eyes, and feel extra hot.
  • 25% – 30%: Fairly fine level, but it still does not reach the healthy humidity rate. You should use a humidifier to raise the rate up.
  • 30% – 60%: Healthy indoor humidity, your body will be comfortable at this level
  • 60% – 70%: At this rate, there can be potential for bacteria and mold spores to build up.
  • Over 70%: The rate is too high. The air is heavier to breathe and you will feel extra hot in summer.
The Cause of Humidity Changes

The change of humidity inside your house is caused by two main reasons: the natural environment and your house hygiene.

Natural Environment

If the causing factor is from the natural environment, your house humidity rate will change accordingly to the season or weather.

For example, in summer, the humidity level will normally become especially high as the hot weather promotes water evaporation, making the air filled with water.

If you do not use any air-improving devices, such as an air conditioner, dehumidifier, or humidifier, you will experience uncomfortable air and exceptionally feel very irritating.

House Hygiene

On the other hand, if the cause is from your house hygiene, it might be that your house has bad air ventilation.

If it happens, you can use devices such as a fan, an air conditioner, a humidifier, or a dehumidifier to increase or reduce the humidity rate.

Also, if there is a water leak somewhere or where usually exposed to water, the humidity rate can be higher than in other places.

You might not feel the change since that damp area only influenced areas near it. However, you might be uncomfortable with the odor as this creates an ideal condition for the build up of mold spores.

There’s a lot more to discuss, and we already have a humidity guiding article here which talks about this issue in detail.

Now we will dig into more detail about low and high humidity rates:

Low Humidity

Low humidity starts from below 30%. At this rate, it is extremely dry as it lacks water vapor. This mostly happens in winter, when the air is too cold to hold water.

As a result, your skin will escape water vapor faster than normal. If it is not monitored, you can experience skin dryness and flaking. Also, when the air is too dry, the air you breathe in will lack water.

It needs to moisture the nasal system, so you might experience a sore throat or respiratory disease.

In summer, if your house is badly ventilated, the humidity rate in your room can be very low. It will make you feel extremely hot and dry at the same time.

Also, when there isn’t enough water in the air, the airborne substances can easily travel with a higher density. So you might experience a sore throat and skin problem.

High Humidity

If the humidity in your house is high, which is over 60%, you will also feel very uncomfortable. When the weather gets warm, water evaporates faster in the air, raising the relative humidity rate.

Hence, it could be concluded that summer and spring will have higher humidity than in cold seasons.

High humidity directly affects our comfort. Hot weather paired with high humidity makes you feel even hotter.

The reason is that your skin needs to sweat to cool down the body. When the air has high humidity content, it takes in water vapor really slowly, slowing down the sweating process.

As a result, your skin might feel suffocated, sticky and your body will become hotter.

At the same time, you will feel it is harder to breathe as the air then contains water, making it heavier and less oxygen. This can trigger respiratory disease and asthma.

How to Lower the Humidity?

To lower the humidity rate, you can use the dehumidifier. This machine will suck in water vapor in the air and drop the relative humidity rate in your home promptly. Or else you can use the air conditioner as an alternative.

If the air is too dry in summer and makes your skin uncomfortable, a humidifier would be the best option.

Above are the most common air problems that is borned inside the house. However, we also suffer from those pollutants from outside that dilute our house. And this we will figure out more detail in the next part:

Sum Up

Hopefully, you can get some helpful information about home air pollution in our post and know the problems your home air might or already have met.

Though there are more to discuss in each contaminant, our post has already been too long. So we can only provide simple definitions, the causes, and the effects of the irritants.

For more info, we will have a separate post for each one in the near future, which will dig into the details of the root and provide ultimate helpful tips and guidance.

Together with us, we will build a healthy indoor environment for our healthy life.

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