The 11 Best Air Conditioners of 2023

The LG 6,000 BTU Window Air Conditioner is our top pick

We independently research, test, review, and recommend the best products—learn more about our process. If you buy something through our links, we may earn a commission.

Frigidaire FFRA0511R1 Air Conditioner

The Spruce

A reliable air conditioner is a must-have if you live in a hot climate or need to keep your home cool during the summer months. We researched and tested dozens of air conditioners to find the best options on the market, evaluating them on efficiency, ease of installation, noise level, value, and range of settings. 

Our best overall pick is the LG 6,000 BTU Window Air Conditioner with Remote Control, which is energy efficient, easy to use, and quieter than other models.

 Here are the best air conditioner units.

Our Top Picks

Best Overall

LG LW6019ER 6,000 BTU Window Air Conditioner with Remote Control

LG 6,000 BTU Window Air Conditioner


What We Like
  • Available in multiple sizes

  • Digital controls with remote

  • Energy Star certified

  • Quiet during operation

What We Don't Like
  • Poor installation instructions

  • Larger models require 230-volt outlets

The LG LW6019ER 6,000 BTU Window Air Conditioner is an unbeatable choice for most homes, as it has a sleek, energy efficient design that’s well-priced. While this particular model is rated at 6,000 BTU, the LW6019ER comes in seven sizes up to 24,500 BTU, which can cool down a space over 1,500 square feet, allowing you to find the perfect fit for your home. The unit offers three cooling speeds and three fan speeds, as well as a 24-hour on-off timer and an energy-saving function. This versatility makes it a great fit for almost anyone looking to cool down their space.

On humid summer days, you’ll be glad that this window air conditioner can remove 1.8 pints of liquid from the air per hour, and you can also direct the cool air exactly where you want it with the four-way louvers. Plus, the air conditioner comes with a full-function remote, allowing you to adjust the settings from anywhere in the room. It operates at around 48 decibels on its lowest speed, which is roughly the noise level of a quiet office, and if the power ever goes out during operation, the AC will start back up when it’s restored thanks to its Auto Restart function. 

The LG LW6019ER Window Air Conditioner is a great all-around value, but it isn’t without its flaws. Many find that its installation instructions are vague, so it can be tricky to set up if you’re not familiar with window ACs. Additionally, the larger sizes (18,000 BTU and up) require a 230-volt outlet, which isn’t available in all homes.

Price at time of publish: $310

Cooling Area: 260 square feet | BTU: 6,000 | Filter Type: Washable | Noise Level: 48–52 decibels | Window Size: 22–36 inches | Energy Star Certified: Yes

Best Budget

GE 5,000-BTU Mechanical Window Air Conditioner

ge white window air conditioner


What We Like
  • EZ mount kit included

  • Lightweight

  • 10 temperature settings

What We Don't Like
  • No energy-saving features

  • No remote control

If value is your top priority, it’s hard to beat the GE Mechanical Air Conditioner, which strikes a perfect balance between affordability and performance. While it lacks the bells and whistles of more expensive window air conditioners, this unit is a powerhouse packed into a compact form, weighing just 36 pounds. It kicks out 5,000 BTU that can cool a space up to 150 square feet—roughly a 10-by-15-foot room—and it has 10 different temperature settings, allowing you to find your perfect level of cool. 

This window air conditioner is controlled by two mechanical dials, and it offers two cooling speeds and two fan speeds. It comes with everything needed for installation, including an EZ mount kit, and its washable filter is easy to slide out, making maintenance a breeze. However, this GE window unit is a budget-friendly pick, so it doesn’t have an energy-saving mode, nor is it Energy Star-certified. It doesn’t have a remote control, either, so you have to make adjustments on the unit’s control panel. If you're looking to keep your bedroom cool in the summer and can forego any smart features, this is an excellent pick.

Price at time of publish: $189

Cooling Area: 150 square feet | BTU: 5,000 | Filter Type: Washable | Noise Level: 50 decibels | Window Size: 27.8–36 inches | Energy Star Certified: No

Best Smart

Windmill 8,300 BTU Window Air Conditioner

8,300 BTU 115-Volt Quiet/ECO/Smart Window Air Conditioner

Home Depot

What We `Like
  • Sleek, modern design

  • Smart features

  • Dual filters

  • Easy to install

  • Cosmetic side panels

What We Don't Like
  • Pricey for its size

  • Not Energy Star certified

If you’re willing to spend a little extra for high-tech features and a sleek appearance, the Windmill Air Conditioner, which offers 8,300 BTU of cooling power, is the way to go. While it’s slightly more expensive than other similarly sized window units, this model stands out in many ways. First, it has a modern design, complete with cosmetic side panels, so it's less of an eyesore in your home. Additionally, it offers smart functionality, allowing you to adjust its settings right from your smartphone or connect it to Google Assistant or Amazon Alexa for voice control. 

This window air conditioner is a breeze to set up, as it comes with everything needed for installation, right down to insulation foam. It has three fan speeds and three cooling speeds, and its auto–dimming LED display makes it perfect for use in the bedroom. Plus, the Windmill AC features an activated carbon filter alongside its standard washable filter, helping to remove odors from your space as it cools. The unit isn’t Energy Star certified, unfortunately, but it does use an eco-friendly refrigerant and the brand works to reduce its environmental impact through a partnership with Pachama to reduce deforestation.

Price at time of publish: $395

Cooling Area: 350 square feet | BTU: 8,300 | Filter Type: Washable mesh and activated carbon | Noise Level: 50 decibels | Window Size: 23–37 inches | Energy Star Certified: No

What Editors Say

"I love my Windmill AC! It cools down my apartment quickly and is super quiet, plus just looks nice and unobtrusive. Controlling it from the app is a game changer, especially on hot days when I want to return to a cool apartment without leaving the AC on while I'm out."—Nicole Lund, Senior Commerce Editor

Best for Large Rooms

LG LW2217IVSM 22,000 BTU Dual Inverter Window Air Conditioner

LG LW2217IVSM 22,000 BTU 230/208-Volt Dual Inverter Window Air Conditioner


What We Like
  • Sleek appearance

  • Smart features

  • Quiet operation on low settings

  • Energy Star certified

What We Don't Like
  • Requires 230-volt outlet

  • Heavy

The LG LW2217IVSM Dual Inverter Window Air Conditioner is powerful enough to cool a space up to 1,300 square feet, yet it’s still Energy Star certified and uses 40 percent less electricity than similarly sized models. This window unit has a sleek design, complete with a digital control panel and remote, and it’s also equipped with smart features, allowing you to adjust its settings from the LG ThinQ app. You can even control it with voice commands through Amazon Alexa or Google Assistant. 

This large air conditioner offers four cooling and fan speeds, as well as an auto cool setting, and its louvers can be adjusted in four different directions. The 3-in-1 design has fan and dry settings, in addition to traditional cooling, and you can program it with a 24-hour on/off timer. The control panel will remind you when the filter needs to be cleaned, and despite its size, this air conditioner can operate as low as 44 decibels on certain settings. 

However, keep in mind that this is a large unit—not only does it require a fairly large window for installation, but it also weighs more than 110 pounds. You’ll likely need assistance installing it, and it needs to be plugged into a 230-volt outlet, which aren’t standard in most homes.

Price at time of publish: $669

Cooling Area: 1,300 square feet | BTU: 22,000 | Filter Type: Washable | Noise Level: 44 decibels | Window Size: 29–41 inches | Energy Star Certified: Yes

Best for Small Rooms

Frigidaire FFRE053WAE Window Air Conditioner

Frigidaire FFRE053WAE Window Air Conditioner


What We Like
  • Affordable

  • Energy Star certified

  • Lightweight

  • Extra-long power cord

What We Don't Like
  • Noisy

For smaller rooms, the Frigidaire FFRE053WAE Window Air Conditioner is an affordable choice that’s compact, lightweight, and Energy Star certified. It’s rated at 5,000 BTU, which is ideal for small spaces, and despite its low price, it comes equipped with a variety of useful features, such as a programmable 24-hour timer and remote control. The unit has a digital control panel, and there are auto, dry, fan, and eco settings to choose from, as well as traditional cooling. 

This air conditioner weighs under 40 pounds, making it easier to install than heavier models, and it has optional side panels that adjust to fit your window. It has an extra-long power cord that saves you from having to use an extension cord, and the unit’s filter can simply be removed and washed to keep the AC functioning at peak efficiency. The only real downside of this air conditioner is that it’s louder than many other, operating at 56 decibels, which is fairly noisy when you’re in a small room.

Price at time of publish: $219

Cooling Area: 150 square feet | BTU: 5,000 | Filter Type: Washable | Noise Level: 56 decibels | Window Size: 23–36 inches | Energy Star Certified: Yes

Best Design

July Window Air Conditioner

July Window Air Conditioner


What We Like
  • Variety of finishes and front panels

  • Easy to install

  • User-friendly app

  • White-glove installation in select locations

What We Don't Like
  • Waiting list for purchase

  • Expensive for its size

The July Window Air Conditioner is one of the most stylish options you can buy, boasting a modern silhouette and nine different front panel options. The July AC comes in two sizes—6,000 or 8,000 BTU—and it’s also easy to install thanks to its unique frame. First, you secure the frame into your window, then you simply slide the air conditioner into the frame, where it clicks into place. Plus, if you live in certain areas, July offers white-glove installation and will take away your old AC unit.

In addition to its attractive design, the July AC offers a variety of high-tech features. It’s equipped with smart functionality, allowing you to control its settings via the user-friendly app, and it can be connected with Amazon Alexa and Google Assistant. Additionally, it can be outfitted with air-purifying filters to help remove fine particulates like pollen, pet dander, and dust mites from your home. 

The biggest downside of this stylish air conditioner is that you’ll have to wait to get it—you have to reserve a unit with a $50 deposit to guarantee a delivery in a few months, as the ACs sell out extremely quickly. Additionally, you’ll be paying a premium price for these high-end units, which are quite a bit more expensive than standard units with the same BTU ratings.

Price at time of publish: Starts at $399

Cooling Area: 350 square feet | BTU: 8,000 | Filter Type: Washable or air-purifying | Noise Level: 50–54 decibels | Window Size: 20.4–39 inches | Energy Star Certified: No

What Our Editors Say

"When someone walks into my apartment for the first time, they always compliment my July air conditioner. It really is a beautiful AC. I opted for the sunset-colored front panel to match my bedroom decor, but I love that I can switch it out to a more neutral or bold tone in the future."—Erin Johnson, Commerce Editor

Best Quiet

Midea MAW08V1QWT 8,000 BTU U-Shaped Inverter Window Air Conditioner

Window Air Conditioner


What We Like
  • Available in multiple sizes

  • Energy Star Most Efficient certified

  • Extremely quiet

  • Wi-Fi enabled

  • Still able to open window

What We Don't Like
  • Tricky to install

  • Display light can’t be turned off

If you’re looking for an air conditioner for your bedroom or child’s nursery, the Midea U-Shaped Inverter Window Air Conditioner is one of the quietest models you’ll find, operating at just 42 decibels. It makes significantly less noise than other models thanks to its unique U-shaped design, which uses your window to block noise from the compressor. Additionally, this window AC is extremely energy efficient—it’s actually certified as Energy Star Most Efficient, meaning it saves 35% more energy than other traditional units.

The Midea Air Conditioner is available in several sizes, ranging from 8,000 to 12,000 BTU, and it comes with smart features that allow you to control its settings from your smartphone or via a smart assistant like Amazon Alexa. The U-shaped design allows you to open your window freely, bringing in fresh air on nice days, and the unit has an anti-theft mechanism that locks the window when it’s closed. 

Because the design is unconventional, it can be a bit tricky to install this air conditioner—you’ll likely want to watch the brand’s installation video to get a better idea of how it works. Additionally, the display doesn’t dim or turn off, which can be a bit bothersome in dark rooms.

Price at time of publish: $399

Cooling Area: 350 square feet | BTU: 8,000 | Filter Type: Washable | Noise Level: 42 decibels | Window Size: 22–36 inches | Energy Star Certified: Yes

Best Wall

Keystone 12,000 BTU Through-The-Wall AC

Keystone 12,000 BTU 115V Through-The-Wall AC


What We Like
  • Trim kit included

  • Easy-access washable filter

  • Temperature-sensing remote control

  • Energy Star certified

What We Don't Like
  • Noisy

Through-the-wall air conditioners are a more permanent option than window units, and the Keystone Wall AC is a top choice for rooms up to 550 square feet. This unit will fit into existing 24.5-to-27-inch wall sleeves, and it comes with foam seals and the trim kit needed to retrofit the AC into an existing sleeve. The 12,000-BTU model is Energy Star certified and can dehumidify up to 2.5 pints of moisture per hour. It also offers three cooling modes and three fan speeds to suit you and anyone in your family's needs.

One of the coolest features about this wall air conditioner is its temperature-sensing remote, which has a built-in thermostat. You can place the remote on the other side of the room, and the air conditioner will monitor the temperature across the whole space, not just in its immediate vicinity. Other useful features include a front-access washable filter and four-way air flow direction, as well as a programmable 24-hour timer. The unit has an energy-saver mode, as well, but keep in mind that it’s quite loud as far modern ACs go, operating at around 60 decibels.

Price at time of publish: $700

Cooling Area: 550 square feet | BTU: 12,000 | Filter Type: Washable | Noise Level: 60 decibels | Window Size: N/A | Energy Star Certified: Yes

Best Portable

LG Electronics LP1419IVSM 14,000 BTU Portable Air Conditioner

LG Electronics LP1419IVSM 14,000 BTU Portable Air Conditioner


What We Like
  • Quiet operation

  • Powerful dehumidifying

  • Easy to install

  • Smart features

What We Don't Like
  • Fairly short vent hose

  • Not Energy Star certified

The LG LP1419IVSM is a top choice among portable air conditioners thanks to its low noise level and powerful cooling abilities. The 14,000-BTU model can be used in rooms up to 500 square feet and will remove up to 6.7 pints of moisture from the air per hour, and its dual inverter technology uses up to 40 percent less electricity than other portable ACs. However, it’s not Energy Star certified. This AC operates as quietly as 44 decibels on its lowest setting, and it even offers Wi-Fi connectivity, allowing you to adjust its settings from the LG ThinQ app or via Amazon Alexa or Google Assistant. 

This portable air conditioner has rolling casters, and it’s much easier to set up than a window unit—all you have to do is install the window vent kit. Keep in mind that the hose is only 35.5 inches long so it will need to be fairly close to your window. It offers three cooling and fan speeds, as well as an auto-swing air vent, and you can set it to turn on and off automatically with its built-in timer. The AC even comes with a built-in accessories tray that allows you to keep the vent hose and window kit neatly stored when it’s not in use.

Price at time of publish: $689

Cooling Area: 500 square feet | BTU: 14,000 | Filter Type: Washable | Noise Level: 44-53 decibels | Window Size: N/A | Energy Star Certified: No

Best Over-the-Sill

Soleus Air 8,000 BTU Hybrid Window Air Conditioner

Soleus Air 8,000 BTU 115-Volt Hybrid Window Air Conditioner


What We Like
  • Extremely quiet operation

  • Easy to install

  • Temperature-sensing remote control

  • Doesn’t block window

  • Available with or without Wi-Fi

What We Don't Like
  • May not fit all windows

  • May need to manually drain

It couldn’t be easier to install the Soleus Window Air Conditioner. Its unique over-the-sill design simply slips into place over your windowsill—no awkward balancing or hole-drilling required—and you’ll still have an unobstructed view out the window. Its 8,000 BTU cooling power can be used in rooms up to 375 square feet, and the unit is available both with or without Wi-Fi connectivity, so you can choose whether you want to control it from your phone or not.

Another major perk of this air conditioner’s saddle-shaped design is that the condenser is located outside your window, making it extremely quiet during operation. In fact, you’ll barely be able to hear it on sleep mode. Additionally, the AC has a temperature-sensing remote control that helps ensure your room doesn’t have any hot spots. The unit has a 24-hour timer, as well as energy-saver and auto modes, but make sure to measure your window before you buy, as it only offers 11 inches of clearance over the sill. It's not listed that you need to drain the AC, but some customers in high-humidity climates reported that they had to manually drain it.

Price at time of publish: $570

Cooling Area: 375 square feet | BTU: 8,000 | Filter Type: Washable | Noise Level: 41 decibels | Window Size: 24–48 inches | Energy Star Certified: Yes

Best Ventless

Hessaire MC37M Portable Evaporative Cooler

Hessaire MC37M Portable Evaporative Cooler`


What We Like
  • Manual or continuous fill

  • Large coverage area

  • Lightweight

  • Easy to operate

What We Don't Like
  • Not effective in high humidity

  • Unattractive design

If you live in a climate with low humidity, you can often use an evaporative cooler (also called a swamp cooler) instead of a traditional air conditioner. The Hessair MC37M Evaporative Cooler can cool down an area up to 950 square feet, and it’s significantly more affordable than an air conditioner offering similar coverage. Plus, this lightweight unit is extremely straightforward to operate, and it can be hooked up to a garden hose for continuous filling and uninterrupted operation. 

This evaporative cooler has three fan speeds and an oscillation option. It works by pulling hot air through a water-soaked filter using a fan to decrease the ambient temperature. It offers air flow up to 3,100 cubic feet per minute (CFM), and its 10.3-gallon water tank offers up to four hours of operation if you choose to manually fill it. While the Hessair Cooler is certainly a great value, it won’t work well if you live somewhere with high humidity levels, and it’s also somewhat of an eyesore with a large, clunky design.

Price at time of publish: $371

Cooling Area: 950 square feet | BTU: N/A | Filter Type: Not listed | Noise Level: 59 decibels | Window Size: N/A | Energy Star Certified: No

Final Verdict

One of the best air conditioners you can buy today is the LG Energy Star Rated 6,000 BTU Window Air Conditioner. This unit cools efficiently, has an included remote control and adjustable louvers that make operation a breeze, and it also comes in larger sizes if you need to cool a substantial space. If you’re willing to spend more on a high-end air conditioning unit, the Windmill Window Air Conditioner has a sleek modern design with smart features so you can control its settings right from your phone.

What to Look for in an Air Conditioner


When shopping for an air conditioner, one of the first things you’ll want to consider is the style that works best for you. There are several options available, and they vary widely in terms of cost, capability, and installation requirements.

Two of the most common options for occasional users are portable and window air conditioners. Both of these options are fairly inexpensive and can be easily installed without professional help. However, the downside of these options is that they’re typically only powerful enough to cool one room at a time, which means you’ll need multiple units if you want air conditioning throughout your home.

"Window ACs can be temporarily installed," explains Chris Roth, CEO and owner of National Technical Institute and a licensed HVAC technician. "If you are renting, this may be a good choice as you can take the unit with you when you move. You will, however, need a frame to secure the unit in a window which could require hiring some outside help."

"A portable unit can be on wheels and rolled from room to room and includes a tube to exhaust heat out of a window or through an opening in a wall," he says. "It is usually easy to store and is very versatile. It will, however, take up floor space and the exhaust tube must be re-positioned every time it is moved."

Another option is a through-the-wall or built-in air conditioner, which is a permanent style. These styles are installed into a “sleeve” in an exterior wall of your home. This is ideal if your room doesn’t have an acceptable window. However, as you may have guessed, this style of air conditioner requires a more complex initial installation, since you’ll need professional help to cut an appropriate-sized hole in the wall.

For more comprehensive air conditioning, you may want to consider a ductless mini-split system. This style of air conditioner has gained popularity lately, as it’s a good permanent alternative for homes without central HVAC. As its name implies, there are no ducts required, and these units are typically more powerful than window units. However, mini-split systems are also fairly expensive and complex to install.

Finally, there are central air systems, which require ductwork throughout your home. These are the most expensive and complicated to install and, as such, are typically most common in newly constructed homes.

Unit Size

If you’re going with a window or wall unit, measure the height and width of the opening to ensure you pick a compatible unit. It’s also beneficial to consider the weight of the unit, as this will determine whether you’ll need help moving and installing it. Don't assume the most powerful unit is the right one for your space, as installing an oversized unit can negatively affect your room's humidity, and you'll have to constantly turn it on and off.

Room Size and Location

Next, you’ll want to consider where you plan to put the air conditioner and how much square footage it needs to cool. "The size of the room or house dictates the size of the air conditioner," explains Roth. "The right-sized air conditioner is important for the efficiency and lifespan of your AC."

The amount of heat an air conditioner can remove from a room is measured in BTUs, or British Thermal Units—larger rooms require a unit with a higher BTU. Here’s a general breakdown of the recommended room size and BTU:

  • 100-300 square feet: 5,000-7,000 BTU per hour
  • 300-450 square feet: 8,000-10,000 BTU
  • 450-550 square feet: 10,000-12,000 BTU
  • 550-700 square feet: 13,000-14,000 BTU
  • 700-1,000 square feet: 18,000 BTU
  • 1,000+ square feet: 20,000 BTU and up

You’ll also want to consider the location of the room as you decide what BTU is best. For instance, a room that has several large windows and gets direct sunlight for several hours a day will likely be hotter and therefore need a more powerful air conditioner. In this situation, experts recommend increasing the BTU by at least 10 percent. Similarly, if your air conditioner will be in the kitchen—and, as a result, will have to combat the heat from the stove—you’ll want to bump up the capacity by about 4,000 BTU.

Noise Level

If you plan to use your air conditioner in your bedroom or living room, you may be concerned with how much noise it produces. The noise level of appliances is typically measured in decibels, but since we don’t use this measurement in our daily lives, most people don’t know what “40 decibels” sound like. This can make it tricky to pick the best option for your needs.

In general, a standard air conditioner operates between 40 and 60 decibels. For reference, TVs usually operate at around 70 decibels, and normal talking falls between 40 and 60 decibels. So if you buy an air conditioner that operates at 60 decibels, it may interfere with your conversations or TV show. The quietest air conditioners out there operate at around 35 to 40 decibels, and their noise level is compared to that of a desk fan.

  • How do air conditioners work?

    All types of air conditioners work in pretty much the same way. First, they extract air and filter out any dust or impurities. That air is then passed over the cooling or evaporating coil, and the coil absorbs the heat. At the same time, during this step, moisture from the air is reduced to dew on the surface of the coil, effectively decreasing the humidity level in the room. Finally, the air is pushed back out of the device, lowering the room's overall temperature.

  • What types of air conditioners are there?

    There are several different types of air conditioners. Window units tend to be the most popular because they're affordable and easy to install, though some homes and apartments with unusually shaped windows may not accommodate them. Portable units are a great pick because they can be moved from room to room, but they also require more maintenance and aren't as efficient. Built-in or split systems offer a more permanent solution but require professional installation and can be costly.

  • How do you clean a window air conditioner?

    To clean your window air conditioner, check the filter each month, and clean it as needed. Also, take a look at the water pan inside the unit, and wipe it with a rag or sponge—this will help ensure proper drainage of the condensate created by the unit. It also helps prevent mold growth.

  • How do you install a window air conditioner?

    If you have basic DIY skills and some tools you most likely can install a window air conditioner yourself—although, because some units are very heavy and cumbersome, you might want to enlist a friend to help you. For those who aren't confident about installing an air conditioner themselves, you can ask the retailer for installer recommendations when you're purchasing a new one, or try a service like HomeAdvisor.

  • How much does an air conditioner cost?

    The cost of an air conditioner varies by type and functionality—you can spend anywhere from $100 to several thousand dollars. Window models start at around $100 but can cost upward of $1,000 if you need one with advanced features and a high BTU capacity. Portable air conditioners tend to be slightly more expensive, typically costing between $200 and $500. Wall air conditioners generally cost $400 or more, and mini-split options start at around $800—plus the cost of installation. Central air systems are often desirable because they can be used for heating, as well, but you’ll likely pay several thousand dollars for the system and installation.

  • What are BTUs and why do they matter?

    The amount of heat an air conditioner can remove from a room is measured in BTUs, or British Thermal Units—larger rooms require a unit with a higher BTU. Energy Star recommends units around 6,000 BTU for rooms up to 250 square feet; 8,000 BTU units up to 350 square feet; 10,000 BTU units up to 450 square feet; and 12,000 BTU units up to 550 square feet.

Why Trust The Spruce?

This article was written by Camryn Rabideau, a freelance writer and product tester for The Spruce. While researching air conditioners, she spoke with Chris Roth, CEO and owner of National Technical Institute and a licensed HVAC technician, for insights on selecting the best model for your home.

Based on his recommendations, she vetted each air conditioner for its cooling power, noise level, settings, and energy efficiency, and she scoured dozens of user reviews for insights on the installation and operation of different units. She personally owns and loves the Windmill AC, which she uses in her bedroom during the summer thanks to its quiet operation. 

Article Sources
The Spruce uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Room Air Conditioners. United States Department of Energy and United States Environmental Protection Agency.

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