Best Air Purifier for Open Floor Plan In The Market 2021
by Liz Gonzales
As you are have come here, I assume that you are looking to buy the best air purifier for open floor plan. Well, that's really a wise decision. Air Purifiers not only protect your health but also do their part in saving the environment.
If you decide to look around a few of these products and do some research, then I assure you that it's not going to be an easy task unless you spend some quality time reading about air purifiers. I don't intend to scare you, but the reality is that there are a lot of technical terms and massive scientific jargon associated with these products.
Editor's Recommendation: Top Air Purifiers for Open Floor Plan
Today's market is literally swarmed with thousands of air cleaners and almost all of them promise to deliver the best quality air. But how much belief do you have in their claims? To start with, you have different types of home air purifiers to consider and compare, such as HEPA versus Ionic air purifiers. Then there are different brands, including Honeywell and BlueAir.
Worse, many online and offline vendors only provide product specifications which, in our opinion, is totally meaningless because unless you understand the significance of each feature, you cannot make a great purchase.
Therefore, it is not surprising that many people end up buying the wrong ones. Considering the high cost of a home air cleaner and the potential health hazard you can be exposed to with the wrong products, this is the mistake you do not want to make.
But, in today's busy world, who would have the time to do extensive research on home air purifiers? After all, visiting one website after another in an effort to do the research takes a lot of time.
Here at Pure Air Hub, I write informational articles and reviews on air cleaners in a concise and easy to understand manner. I wish to make this place a knowledge hub where you can find all there is to know about air purification technologies and top-performing product reviews. I really hope my website helps you in finding the best air purifier wirecutter that meets your expectations and satisfies all your requirements without breaking your bank!
10 Best Air Purifier for Open Floor Plan Reviews
1. Germ Guardian True HEPA Filter Air Purifier: The Best Budget Sanitizer
The UV-C Light
One of the most significant issues that many air filters share is that it is practically impossible to control what the UV-C light does. Most UV-C lights just stay on with most air filters, requiring you to constantly replace them.
As insignificant as this may seem, the Germ Guardian By Guardian Technologies contains a function that toggles the UV-C light. This is incredibly useful if you do not need the light on all the time. It means you do not need to replace the UV-C light all the time.
Another nice quality about the Germ Guardian is the signature sleep mode function. Most air filters can be unnecessarily loud, and it can be difficult to concentrate in a room that has a loud air filter running. The sleep mode function solves this problem.
Aside from trapping allergens like most other air purifiers, the Germ Guardian also reduces odours. This is a nice feature of it no matter how insignificant it may appear to be.
If you are looking for the best air purifier for open floor plan, you do not need to look elsewhere. The Germ Guardian is most effective in an area that measures 167 square feet. While the Germ Guardian is very effective in and of itself, it will struggle in a large area.
2. LEVOIT Air Purifier: The Best Filtration System For Home
Fortunately, Levoit's air purifier solves this problem in that it indeed clears odours, no matter where the odours come from. Whether the odours come from polluted air or just from cooking a lot, they will be removed when you turn Levoit's air purifier on. Most air purifiers do a really good job of clearing any kind of polluted air from an area. However, something that many of them can improve upon is clearing odours, especially odours that are created by smoke.
A lot of air purifiers can be extremely loud to the point where they can possibly be troublesome. Fortunately, you can adjust the volume levels in Levoit's air purifier very easily and you can adjust it to three distinct levels. You can also adjust light levels of Levoit's purifier which is often underlooked but appreciated nonetheless.
Levoit's air purifier is extremely small and it is only designed to clear air in very narrow and small spaces. If you attempt to purify the air in a large space with it, you will be disappointed and you will definitely want to look for something else.
3. Hamilton Beach TrueAir Air Purifier: The Best HEPA Filter For Home
Because they filter out so much polluted air, a good amount of air purifiers are very difficult to clean. Cleaning the common air purifier can be an extremely frustrating task and it can take a very long time or you will need to spend money on expensive replacement filters.
Easy To Purifi
Fortunately, it is very easy to clean with the TrueAir. To clean it, all you need to do is vacuum it. Simply running a hand vacuum over the filter is often all you need to do to clean the TrueAir. This means you will not need to buy additional filters unless you absolutely need to.
A lot of air purifiers do not compliment the look of the rooms they are placed in. most of the time, they will stand out, and not in a good way. Fortunately, the stylish design of the TrueAir makes it stand out in a good way. While this may be negligible to some, it is important in its own right.
The UV-C Light
The TrueAir does not perform as well as other air purifiers. While a decent amount of air purifiers contain UV-C lights that filter out even more polluted air, TrueAir does not contain this feature.
Odour control is something else that TrueAir does not contain. And additionally, the only real filtering functions it contains are the basic ones. It seems like TrueAir favours aesthetics over function.
4. Pure Enrichment Room Air Purifier: The Best Filtration System
HEPA filter And The UV-C light
Nothing will clear the air of undesirable particles more than the PureZone. It contains a HEPA filter that eliminates nearly all unwanted dust, pollen, smoke, and any and all odours. The UV-C light that it contains is stronger than most other UV-C lights in air purifiers and will eliminate any given micro-organism.
An air purifier as strong as this is usually extremely loud, but this is not the case with the PureZone. Operating at a maximum of 30 decibels, it is much quieter than other air purifiers of its kind. You will not need to worry about the PureZone ominously humming to where you can hear it outside.
Smart Energy Saver
It can be easy to leave air purifiers on, especially quiet ones such as the PureZone. However, the PureZone contains an automatic timer that can turn it off after 2, 4, or 8 hours of being used. This will help you save energy that you might have wasted by forgetting to turn it off.
Set Up The PureZone
It is claimed that it is easy to set up the PureZone, but when you compare it to other air purifiers this is not true. Most other air purifiers follow a "plug and play" set up, but there is some construction necessary for the PureZone. You will also find yourself replacing the filter a lot.
5. Honeywell HPA300 HEPA: The Best Breathe Cleaner
It is rare to find an air purifier that can clear the air in an area that is larger than 160 or so square feet that are actually efficient in what it does.
Most air purifiers that are capable of purifying the air in large areas typically do not do their job too well: They are limited in what kinds of particles they can eliminate or micromanage.
The HPA300 by Honeywell changes all that, as it is able to purify an area up to a staggering 465 square feet. This is an air purifier that you should pay attention to if you want one for a large office or living room.
Probably the best part about the HPA300 is that it does what all of its smaller counterparts can do. It can capture common unwanted air particles as well as airborne particles. You will get the same effectiveness as the purifiers that purify only 160 or so square feet of area with the HPA300.
You have a choice of how intense you want the HPA300 to act, as well. Unlike with most air purifiers of its size, you are not tied down to one intensity level.
The only real issue with the HPA300 is that it contains two filters. These two filters absorb so much toxic air that you will likely need to replace both filters frequently. If you plan to use the HPA300 on a regular basis, prepare to replace the filters more than you might want.
6. Winix 5500-2 Air Purifier: The Best Reducing Washable
Air purifiers that are rated for rooms over 160 square feet suffer from two common issues. First, they do not contain a lot of options. Most of the time you are locked into one power setting, one sound setting, and even worse, the ability to remove only one grouping of harmful particles.
Another issue that these air purifiers have are the way that their filters are handled. Most large purifiers force you to buy replacement filters and this can be very inconvenient, bordering on frustrating.
The Winix 5500-2 solves both of these problems soundly. It solves the first problem by containing a HEPA filter that can eliminate both allergens as well as airborne pollutants. This filter is also washable as well as replaceable. If you do not want to replace your filter, you do not need to. This is probably the best thing about the Winix 5500-2.
You would think that an air purifier such as the Winix 5500-2 would be very loud, but you would be mistaken. At its loudest, it is only 27.8 decibels loud. This means you will not need to deal with the embarrassing humming that you often get from other air purifiers like it.
The only thing that stands out in a bad way with the Winix 5500-2 is that it is physically massive. It will stand out in any room, and not in a good way. It will get in the way of most things around it as well.
7. KOIOS Air Purifier for Home: The Best Air Filter
The vast majority of air purifiers will only produce an air intake and discharge in one direction. While this is standard and in many ways negligible, there is a significant difference between air purifiers that do this and air purifiers that produce air intake and discharge in all directions.
Smart Way Of Intake And Discharge Air
Koios' air purifier is one of those air purifiers that can purify the air in all directions. You notice a world of difference in the quality of air because of this, and it is one of the best things about Koios' air purifier.
A lot of air purifiers utilize UV light to purify the air. This is slightly harmful to the environment as well as potentially harmful to you because of the ozone that is produced. Fortunately, Koios' air purifier not only contains a HEPA filter, but it is a HEPA filter that does not utilize UV light.
There are a couple of things that set Koios' air purifier back. The first thing is the filter that it uses. Because Koios' air purifier utilizes an ozone-free filter, it will need to be replaced. And replacing this filter will be very difficult because they are not easy to find.
Because its fan moves in all directions, Koios' air purifier is extremely loud. While you can switch between fan speeds, you are still stuck with a purifier that is much louder than the average air purifier.
A good amount of air purifiers that utilize both HEPA and odour removing filters are not as effective as those that use one or the other. This is often because the air purifier is doing too much work in eliminating pollutants and other unwanted particles.
However, air purifiers that use either a HEPA or an odour-removing filter often do not provide the versatility that you might need. Fortunately, Coway's "Mighty" air filter allows you to switch between both filters, which makes things very convenient.
Smart Energy Saver
Most air filters allow you to control the speed of the fan, but not many allow the air purifier itself to go into eco mode. Another very nice thing about the Mighty air purifier is that it actually does contain a feature that will allow you to put it in eco mode to save energy. The Mighty will enter this mode automatically if it does not detect any pollution for thirty minutes. This is another very nice feature of it.
Air Filtration detector
One of the best features about the Mighty is that it contains an LED light that will tell you how clean or dirty your indoor air is. This is an indicator that very few air purifiers share.
Although the Mighty can accommodate room sizes of up to 361 square feet, this capacity is compromised when it comes to certain pollutants. When it comes to eliminating pollen, smoke, or dust, the Mighty can only reach about 250 square feet.
9. PARTU HEPA Air Purifier: The Best Fragrance Sponge
Something that is lacking with a lot of air purifiers is fragrances. While most air purifiers do a good job of clearing the air, you can often smell the filters underneath the purifier. As negligible as this might be, it can be unsavoury.
Partu's air purifier solves this problem by containing a fragrance sponge. You can add a drop of essential oil of your choice along with some water into the sponge below the outlet of the purifier and you will be able to create a fragrance when you turn the air purifier on.
It can be easy to knock over Partu's air purifier because of its upright design. Fortunately, it is possible to lock all of the buttons on the purifier this way nothing happens if it does get knocked over. This is another very nice thing about Partu's air purifier.
You will need to look elsewhere if you were intending on Partu's air purifier to cover an entire room. It is extremely small and is really only designed to purify a cubicle or a large workstation. 107 square feet of coverage is all you will get with Partu's air purifier, and this is certainly not enough for an entire room.
10. LEVOIT Air Purifier for Home: The Best Filtration System Cleaner
Something that is often missing from a good majority of air purifiers is the ability to change filters to meet different needs. Most air purifiers use just one filter for one need: The need to clear the air around you of general pollutants.
Different Filters For Different Pollutants
The Core 300 by Levoit stands out from all the rest in a good way by containing different filters that combat different pollutants. You can put in a filter that combats most common pollutants, a filter that cleans the air of pet allergies, a filter that cleans the air of toxic air such as smoke, or a filter that specializes in environments with a lot of moisture.
Pure Air For 360 Degrees
Resembling a cylinder, the Core 300 is able to circulate pure air for 360 degrees. This is another thing that makes the Core 300 stand out for the better compared to other air purifiers that usually dispense air straightforward.
You will never need to worry about excess noise with the Core 300 either. Operating at 24 decibels, it is one of the quietest air purifiers in existence.
Although the specialized filters are a good idea, The Core 300 lacks in performance compared to other air purifiers. Most air purifiers that use a HEPA filter will be able to filter out any and all pollutants that you need specialized filters for when it comes to the Core 300.
How to Choose Air Purifier for Open Floor Plan: Buying Guide
I'm the kind of person who likes to do a bit of research and learn about the products before making a purchase decision. I assume there would be many others like me who would love to have a dose of information. So if you are one among them then go ahead and read along with this article.
Before making any decision, I suggest you read my purchase guide for air cleaners which will tell you precisely about all the necessary functionalities and important features that you should be looking at an air purifier. The ultimate aim of this guide is to help you make an informed decision.
I've also written quite a few feature specific articles and other informational stuff to make things easier. So I urge you not to be in a hurry and read through the information before selecting the right product that fits in with your requirements.
Also, I have compiled a list of tips for first-time buyers that would definitely come in handy for an inexperienced buyer.
What does CADR mean
The term 'Clean Air Delivery Rate' was actually coined by American Home Appliance Manufacturers (AHAM). In simple terms, CADR is the measure of how effectively an air filter can remove the contaminants and pollutants present in the room and deliver crispy clean air. CADR ratings for Smoke, Dust and Pollen are individually represented.
This is one term that you will be reading a lot about because it is an industry-standard. You can read more on this topic here.
Now that you have a basic understanding of CADR, let's look at some other important details like Air Flow Rate, Purifier sizing and positioning.
Rate of Air Change and Performance
Air Purifiers use a fan to pull in the air which is then forced to pass through the filters. After filtration, the pure air is then pumped out back into the room. The speed of these fans is adjustable. So airflow is directly dependent on the speed of the fan and the number of filters.
'Air Change Rate' in short is the number of times the purifier can clean the air present within the room. So this has a lot to do with the size of the room and also the capacity of the purifier itself.
If the air change rate is too low then you should probably rethink your choice of an air purifier because the indoor air gets stagnant and thus it may negatively affect your health.
Having a proper idea about the size of the room in which the air purifier is going to be placed will definitely help you in choosing the right product. Many people end up buying a purifier that this just too small and have a much lower capacity to purify the contaminated air in their house. Check out my article on choosing the perfect one that fits well for your room size.
This is one of the top priorities that you need to answer after you purchase the air cleaner. For the purifier to work perfectly it has to be placed in such a location where it is not obstructed and will be able to pull in the air much easier. There are several other things that you need to keep in mind before you decide on the placement.
Types of Filters Used
Filters are probably the heart and brain of an air purifier. These filters do all the grunt work of cleaning up the air and arresting all the impurities and contaminants that you don't want to breathe in. Right from the beginning, there have been many innovations and developments in this field, with each one intended to improve the quality of air that is being delivered. Below I have mentioned a few of these filters along with links for each one.
A majority of the air purifiers which you'll be seeing would have these HEPA filters on them. These filters are highly effective and are able to purify the air up to 99.9%. These, when used in combination with other prefilters (like Charcoal filters) will significantly increase the filtering capacity.
Activated Carbon (Charcoal) Filters
These filters help them capture large-sized contaminants like pet hair, dust and other particles of such proportions. When used individually these filters are less effective in cleaning the air. So it is probably best to choose an air purifier that uses these for pre-filtering purposes.
Ionizers, Ultra Violet, and Electrostatic Filters
These filters use a different filtration technology to purify the air and are nowadays used along with HEPA filters. I have made a separate article for each of these. Here you will be able to understand the functioning of air cleaners that use these filtration technologies.
What Is An Acceptable Indoor Air Quality?
How do you know that the indoor air quality of your home is acceptable and up to standard?
This article will help you to answer these questions without having to pay for pricey home air quality inspections.
What is an Acceptable Indoor Air Quality for Your Home?
There are all sorts of indoor air quality standards which an expert individual can measure. However, if you don't want to invest in air quality inspections, then use the checklist below to gauge how clean the air within your home is.
Basically, the air inside your house is acceptable if:
1. Your house has good air changes per hour.
In order for a home to have acceptable indoor air quality, it should have a good ventilation system to ensure air changes. Decent air changes will dilute indoor pollutants considerably and increase air quality. In order to achieve this, not only should a house be aired frequently by opening the doors and windows. But also, it should have a good forced air system for air conditioning and heating as well as a good exhaust fan for windowless areas, such as the bathroom.
How good is good though?
Acceptable indoor air quality standards, including air changes, differ from building to building and room to room. For instance, at the extreme, commercial kitchens should have 20-30 air changes per hour, whereas warehouses only need 1-2 air changes per hour. Air changes required for a house might be closer to that of a classroom, which is 3-4 air changes per hour, provided the members of the family are healthy. The requirement for air changes increases if you have a family member who has medical problems and is sensitive to the quality of indoor air.
But how do you measure the air changes?
In a typical airtight house in the US, where houses are continuously cooled down in summer months and heated up in winter and with minimal air leakage, air change depends a lot on the HVAC system. An HVAC contractor can be called to judge the quality of your HVAC system and to see whether it provides good air changes.
But, if you only want to have a rough idea of how clean your home indoor air is, look at the warning signs below which indicate that your home has a poor air change system :
stalled or smelly indoor air.
condensation along with the window.
dirty central heating or cooling equipment
2. No one has illnesses that can be attributed to poor air quality.
When the air quality of a home deteriorates, the most sensitive member of its inhabitant is usually the first who takes the brunt. These are adults or children who can't stand living in polluted homes and usually have allergies, asthma, other types of lung diseases or multiple chemical sensitivities which make them react to poor air.
If one member of the family starts sneezing, coughing, having headaches, and so forth, after moving to a new home, or after having a new home refurbished, it might be a sign that the air quality is off.
3. The absence of a lifestyle can make the home air quality worse.
Your lifestyle and the lifestyle of other people living with you can also be used as a gauge of your home's air quality. A house full of smokers or pets is very likely to have a poorer air quality in general. Similarly, frequent use of strong cleaning agents and pesticides in a particular house means that the house may have, to some degree, accumulation of toxic fume.
In addition, if your house has just been refurbished, or if you just move into a new home altogether, you should be aware that the off-gassing from paint, new carpet, and so forth, will be present for a period of time.
If you are worried that you don't have an acceptable indoor air quality in your home because of your lifestyle, then it is a good idea to invest in a good quality air purifier.
4. Home is not built in the middle of a polluted environment.
Homes built in the industrial area surrounded by chemical plants have a higher chance of having indoor air quality problems than the ones built in a place where the outdoor air is considerably cleaner.
5. Indoor air pollutant measurement doesn't show an alarming presence of pollutants.
Another way to gauge whether the air inside your home meets the optimal air quality standards is by doing an indoor air quality assessment. EPA recommends that you measure at least the level of radon, a dangerous colourless, odourless, radioactive gas in your home by using a test kit. A more comprehensive test on other indoor air pollutants or even an indoor air quality inspection may be performed if you suspect that the quality of your house air affects the health of the inhabitants.
Additionally, if you're moving to a new home, you may want to couple the general house inspection with an air quality inspection to prevent the problems down the road, especially if one of the members of the family has a medical issue that requires clean air.
You may want to read more about how this affects your health adversely by following this link.
Finally, if the air quality measurement shows no alarming presence of pollutants, you can rest assured that your home has an acceptable indoor air quality.
Safety Concerns On Air Purifier Usage
Are air purifiers safe?
This is a good question to ask prior to buying any purifiers. After all, everybody wants air purifiers to improve their lives, not making them worse.
The short answer to the question of whether air cleaners are safe is: yes. Most air cleaners are safe for general use. However, some of them are not that safe.
So which air cleaners are safe then?
In order to answer these questions, we have to first look at the air purification systems used by home air purifiers because the safety of an air cleaner is closely linked to the air purification system it uses to purify the air.
Among the air purifiers, there are two types that are questionable in terms of safety. They are ozone air purifiers and ionic air purifiers.
Let us explain one by one.
Why Aren't Ozone Air Purifiers Safe?
One of the technologies which can be employed by air purifiers to clean air is ozone, a highly reactive oxidant. Ozone air purifiers are designed to emit a high quantity of ozone so that the ozone can react chemically with airborne particles, hence converting those particles into supposedly harmless chemicals.
Since ozone can irritate soft tissues, including the eyes and the respiratory tracts, the use of such a high concentration of ozone is not safe. In fact, such ozone generators are originally only used for industrial purposes and in places where nobody is going to be present for a while, for instance, for cleaning up empty areas or houses struck by natural disasters.
Unfortunately, some of the ozone air purifiers have made it to the home air purifier market. The manufacturers of course claim that they are safe since most of them are within EPA (Environmental Protection Agency) ozone limit, which is 0.05 ppm. However, EPA found that when used within EPA's ozone limit, this type of air purifier is not effective enough.
On top of that, even when used within EPA's ozone limit, that level of ozone still causes irritation for people who are particularly sensitive to chemicals as well as people with respiratory diseases. Moreover, EPA also found that often, customers put the air purifier in a room smaller than the recommended size, hence the ozone level in that room ends up being higher than what is deemed safe by the EPA.
Therefore, if you want a safe air purifier, it is better to avoid ozone air purifiers. Not only you should avoid them because of the safety issue, but also on the effectiveness grounds.
Are Ionic Air Purifiers Safe?
Another type of air purifier uses an ionizer to clean air up. These air purifiers are called ionic air purifiers. Ionic air purifiers clean air by emitting charged ions (usually negatively charged ions). These ions are expected to bind to airborne particles, hence dragging them down to the floor. This way, the airborne particles are no longer airborne and can be vacuumed away. Some ionic air purifiers, called electrostatic air purifiers, suck ionized airborne particles to the machine and stick them to a pair of electrostatic plates, hence removing them from the room.
The problem with this air purification technology is that it can emit ozone as a by-product. This is because, during the process of ionization, a high voltage has to be applied within the machine, and this process releases an ozone by-product. The amount of ozone emitted is small and most are within the EPA threshold. However, people who have lung diseases including asthma patients should avoid such purifiers since their lungs are already sensitive and easily irritated. In addition, people who are immunity levels are low and have chemical sensitivity should also choose other non-ozone emitting air purifiers. Healthy people generally can tolerate ozone, but if you have a choice, we suggest you avoid these altogether because there are many other good quality air purifiers that are completely safe.
Having said that, it is important to mention that there are some ionic air purifiers that are safe. These air purifiers do not emit ozone or emit negligible (below background) amount of ozone, for instance: the high-quality Blueair ionic air purifiers are completely safe and effective.
Are HEPA air purifiers safe?
HEPA air purifiers are air purifiers that use high efficiency (HEPA) filters to filter out airborne particles. Filtration is basically the oldest way you can clean something up. It works purely by mechanical means.
HEPA air purifiers are safe. Effectiveness varies, depending on the brand. The only drawback is that usually these air purifiers are noisier and you need to replace the filters from time to time. This is in contrast to electronic air purifiers such as ionic and ozone air purifiers. They, in general, are quieter and don't have anything to replace. In the case of electrostatic air purifiers, the only thing you have to be aware of is that you should wash the electrostatic plates regularly to maintain the effectiveness of the machine.
Nevertheless, we recommend HEPA air purifiers highly because of the safety issue.
More Note on Air Purifier Safety For People With Chemical Sensitivity and Asthma.
For most people, as long as an air purifier does not emit ozone, it's safe to buy. People with multiple chemical sensitivity (MCS), and lung-disease sufferers are however a different bunch. If you had such a condition, then it's better to buy a safe air purifier that does not emit any kind of gas. Ozone-emitting air purifiers should definitely be avoided. It is also better to avoid air purifiers that emit gases from materials used for air purifier housing or casing. These gases are usually well-tolerated by normal people but can irritate people with multiple chemical sensitivity or gas sensitivity.
So where do you find such safe air purifiers?
Here are some rules of thumb:
Prefer air purifiers with metal instead of the plastic casing.
Buy premium air purifiers. Not only are they highly effective to alleviate symptoms for people with multiple chemical sensitivity and sensitive respiratory tract, but they are also safe. They do not emit ozone, have a metal casing and use non-toxic paint. In addition, they often have labels or little booklets saying: 'no ozone' and 'no off-gassing' to help customers to identify those safe air purifiers. In addition, if you want to shop for them online, many online allergy stores which carry safe air purifiers put the no-ozone and no off-gassing features in their product description. So it should not be too difficult to identify them.
I have done my best to present this website and make it as informative as possible. In the past, I myself was a victim of various ailments and was prone to allergy attacks. So, in my quest to fight these diseases I came across the best air purifier for open floor plan. Much sooner I realized that not all these purifiers are as good as they say. There is a lot of misinformation floating around on the Internet.
I have spent many hours trying to figure out which purifiers work best for me and during this process, I have gained a lot of knowledge which helped me make a good buy. So I thought that there might be many other people just like me who are equally if not more confused. And as a result, I have decided to combine my reviews. I have provided not only good but also honest reviews.
Liz lives in a suburb in New York city. Both of her parents are the art professors at Sate University of New York. As such, Liz grew up with all kinds of art objects, portraits, and books laying around the home. Liz met up with Linea through another friend in some kind of online art forum. There great minds sparkled to take their passions onto the next level @ linea.io.