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Stay Healthy in Your Home: Tips from an Environmental Engineer on Indoor Air Quality

Our homes harbor an astonishing amount of indoor allergens and pollutants, from known culprits like dirt and dust, to pet dander, cigarette smoke, and more. But some of the most common are things you may not have thought of, like volatiles and combustion-related pollutants from cooking, toxic chemicals off-gassing from personal care and cleaning products, and molds.  

Shelly L. Miller, Ph.D

AHAM recently sat down with Dr. Shelly L. Miller, Ph.D., an indoor air pollution expert and professor at the University of Colorado Boulder, to discuss all things indoor air quality (and portable air cleaners). During our conversation, she shared: 

  • The importance of ventilation for a healthy home 
  • Best practices for improving indoor air quality 
  • Things to look for when choosing a portable air cleaner 
  • How to get the most from your air cleaner 

According to Dr. Miller, most homes are poorly ventilated. While being sealed up tight might be great for energy efficiency, it’s NOT great for indoor air quality. “Ventilation is critical for a healthy indoor environment. By bringing outdoor air inside, concentrations of indoor air contaminants get diluted,” she said.  

Ventilation technology exists with things like heat recovery ventilators (HRV) or energy recovery ventilators (ERVs) that constantly condition and refresh the air inside the home, helping to remove pollutants, allergens, and other types of particles from the air. But, while modern ‘passive’ homes use these technologies, most homes — especially older homes — don’t have the technology, and it can be incredibly expensive to add.  

Other than increasing ventilation, which, again, is a costly fix, Dr. Miller says, “Simple solutions do exist for improving indoor air in homes, businesses, and schools — with the best practices being source control and air cleaning.” Source control means removing the pollution at the source  (such as using a range hood while cooking). Air cleaning, on the other hand, means capturing harmful pollutants after they have been released into the indoor air. This is where portable room air cleaners come into play. Portable room air cleaners represent a quick, accessible option for improving indoor air quality.  

Once you decide to purchase an air cleaner, there are hundreds of models to choose from. Between learning about all the technical features, plus an abundance of acronyms like CADR, ACH, and HEPA that are associated with air cleaners, shopping for the right model can be confusing.  

To determine whether an air cleaner will do the job, Dr. Miller advises to look for third-party certifications, and buy devices tested by the California Air Resources Board (CARB) and/or the Association of Home Appliance Manufacturers (AHAM) (That’s us! More on AHAM’s Verifide® program below).  

Air cleaners are not one-size-fits-all solutions, and there are a few important things to consider when choosing a room air cleaner: 

  • Room size. It’s vital that the air cleaner is capable of effectively covering the size of the room in question. Always check the manufacturer’s specifications for the recommended room size.  
  • Focus on the Clean Air Delivery Rate (CADR). The CADR, which is AHAM’s standard for measuring an air cleaner’s efficacy, helps provide a way to choose an air cleaner based on your specific air cleaning needs. That’s because CADR is a measurement of how fast an air cleaner filters three commonly sized particulate matter: dust, pollen and tobacco smoke. Match your air purifier’s CADR to room size. To do that, follow AHAM’s recommended 2/3 rule, and choose an air cleaner with a dust, pollen, or smoke rating that is two-thirds the size of the square feet of the room. That means a room that is 200 square feet would require an air cleaner with a CADR of at least 132. If you live in an area with a high pollen count, consider air cleaners with higher ratings for filtering pollen. If dust is an issue, pay closer attention to the unit’s rating for dust. And if you have smokers in the home, look for higher ratings for smoke. The higher the CADR number for each pollutant, the faster the unit filters the pollutant from the air.  
  • If wildfire smoke is your concern, the room sizing recommendation changes. Wildfires drive smoke and ash to very high levels, often requiring masking outdoors. Portable room air cleaners that will be used to mitigate wildfire smoke should have a smoke CADR equal to the room size.   

Knowing your unit’s CADR can help you determine how many air changes per hour (ACH) it is capable of, or how many times all the air in a space is cleaned. The bigger the room, the more airflow you need to clean all the air in it.   

The U.S. Environmental Protection Agency recommends looking for air purifier models that provide at least 4.8 ACH for the recommended room size to help improve your indoor air quality. A device labeled to provide 4.8 ACH in a 10’x 12’ x 8’ room can treat the air in a room of that size 4.8 times each hour. In general, according to EPA, a device with much higher ACH for a room is not recommended, as it provides minimal air quality improvements for higher energy use.   

It is important to note that claims regarding ACH and CADR have not been substantiated unless the product has been tested to the ANSI/AHAM AC-1 test method through a program that third-party verifies products such as the ENERGY STAR program or AHAM Verifide. 

When it comes to using air cleaners properly, a good rule of thumb is to place an air cleaner in each room. “It’s best to place the air cleaner close to the source of pollutants,” Dr. Miller says. “For instance, in a kitchen without an exhaust hood, put the air cleaner close to the stove.” Otherwise, air cleaners should be positioned as close as possible to the center of the room to maximize airflow. It’s also important to change the air cleaner filter regularly, according to the model’s use and care instructions. 

ABOUT AHAM VERIFIDE 

When you’re ready to purchase an air cleaner, always look for the AHAM Verifide® mark. Room air cleaners certified through the AHAM Verifide program have been rigorously tested by an independent laboratory to ensure the product will perform to the manufacturer’s product claims for the suggested room size. The AHAM Verifide mark can be found on product packaging.  

To find AHAM Verifide® room air cleaners, use AHAM’s online searchable directory to locate the model that’s right for you. 

Find a Certified Room Air Cleaner Here 

ABOUT DR. MILLER 

Dr. Shelly L. Miller is a Professor of Mechanical Engineering and faculty in the Environmental Engineering Program at the University of Colorado Boulder, holding an M.S. and Ph.D. in Civil and Environmental Engineering from University of California, Berkeley, and a B.S. in Applied Mathematics from Harvey Mudd College. Dr. Miller studies urban air quality and works diligently to understand the impact of air pollution on public health and the environment. She is an expert on indoor air quality, airborne infectious disease transmission, air pollution and air cleaning technologies, and assessing and mitigating urban air pollution exposures in underserved communities. Dr. Miller is a member of the Academy of Fellows of the International Society for Indoor Air and Climate (ISIAQ) and is also an Associate Editor for Environmental Science and Technology. Dr. Miller has published over 100 peer-reviewed articles on air quality including timely papers on COVID-19 transmission and control, and is the principal investigator on the National Science Foundation’s Social Justice and Environmental Equity Project in Denver (SJEQDenver.com). 

Make 2025 the Year for Cleaner Air

As we usher in 2025, many of us reflect on ways to improve our lives. While common resolutions include eating healthier or exercising more, let’s focus on something that is often overlooked, but important to health and well-being: indoor air quality (IAQ).

During winter, when we spend more time indoors with windows sealed tight against the cold, it is easy for pollutants to accumulate, affecting our health and comfort. According to the U.S. Environmental Protection Agency (EPA), levels of indoor pollutants can be two to five times—and occasionally more than 100 times—higher than outdoor levels. Indoor pollutants include allergens, smoke, pet dander, mold, bacteria, respiratory viruses, and more. 

Why not make a resolution to improve your indoor air quality? Here’s how to start.

Why Indoor Air Quality Matters

According to the Asthma and Allergy Foundation of America (AAFA), poor indoor air quality can lead to allergies, respiratory issues, and even long-term health problems. Dust, mold, pet dander, and other pollutants all contribute to indoor air pollution. And during the winter, when we spend 90% of our time indoors, the impact is even greater. The good news is that even small changes can improve indoor air quality.

Tips for Improving Indoor Air Quality

  1. Invest in a portable air cleaner. An air cleaner can remove dust, allergens, and other particles from the air. Choose one sized appropriately for your space and place it in high-traffic or sleeping areas for maximum benefit. When you are ready to purchase an air cleaner, always look for the AHAM Verifide® (learn more about AHAM Verifide below).
  2. Ventilate while cooking. Cooking can release smoke, grease, and other pollutants into the air. An externally vented range hood can capture these emissions and expel them outdoors. If you already have one, ensure it is functioning well and clean the filters regularly. And if you don’t have an externally vented range hood, you have other options to improve ventilation while cooking.
  3. Ventilate your home. Letting in fresh air for even 10 minutes a day can help dilute indoor pollutants. Use exhaust fans in the kitchen and bathrooms to reduce moisture and odors.
  4. Reduce dust and allergens. Vacuum regularly using a vacuum with a HEPA filter. Wash bedding weekly in hot water and use dust-mite-proof covers on pillows and mattresses.
  5. Control humidity levels. High humidity encourages mold and mildew growth, while low humidity can irritate your skin and respiratory system. Aim for a humidity level between 30-50%. A humidifier or dehumidifier can help keep it in check.

Benefits of Cleaner Indoor Air

By improving your indoor air quality, you may notice:

  • Fewer respiratory issues and allergies.
  • Better sleep quality.
  • A fresher, more inviting home environment.
  • Peace of mind knowing you are creating a safer space for your family.

Start 2025 Off Right

Commit to cleaner indoor air as your New Year’s resolution and enjoy the benefits of a healthier home environment all year long.

About AHAM Verifide

When you’re ready to purchase an air cleaner, always look for the AHAM Verifide® mark. Room air cleaners certified through the AHAM Verifide program have been rigorously tested by an independent laboratory to ensure the product will perform to the manufacturer’s product claims for the suggested room size. AHAM’s standard for measuring an air cleaner’s efficacy is called the Clean Air Delivery Rate (CADR). CADR indicates the volume of filtered air an air cleaner delivers, with separate scores for tobacco smoke, pollen and dust. The higher the CADR number for each pollutant, the faster the unit filters the air.

To find AHAM Verifide® room air cleaners, use AHAM’s online searchable directory to locate the model that’s right for you.

Find a Certified Room Air Cleaner Here

Beat the dry winter air with a humidifier

If you need another reason to dislike winter, dry winter air is a good one. It can dry out your nasal passages, which can make it tougher to bounce back from a stuffy nose. The dry air can aggravate asthma symptoms and cause dry skin. Over time, it can also damage your wooden floors and furniture and hurt the health of your houseplants.

Clearly, if you can offset the dry air, you should. And a humidifier is your go-to appliance for balancing out the air in your home as you count the days until spring. If you are shopping for a humidifier, there are a few things to consider while you’re making your choice.

Size of the room

If you have an idea of where you’re going to primarily use your humidifier, it’s important to know the size of your room. If you buy a humidifier that’s too large for the space, you’ll not only make the room uncomfortably humid, but also create an environment favorable to mold and mildew. Too small, and your humidifier won’t be able to adequately humidify the space. Humidifiers designed for larger spaces will have larger water tanks.

Check the labeling of the humidifier, which should have information about how big a space the model is made for. Know the square footage of your room and choose the model that’s appropriate for the space.

Warm vs. cool

Appliance manufacturers produce humidifiers that can put out either warm or cool humidity. Your choice is largely a matter of personal preference. Both warm and cool-mist humidifiers will increase the humidity in your home.

Filter or no filter?

Both filtered and filter-free humidifiers will humidify the air. A filtered model will remove minerals from water before the water is put into the air. However, the filter will need to be changed regularly, possibly every 1-2 months.

Filter-free models don’t require changing filters. But, you may notice an accumulation of minerals, possibly as a fine white dust, on the outside of a filter-free humidifier. However, some models come with demineralization cartridges, which need to be replaced periodically.

You may notice a difference in the way filtered and filter-free humidifiers put moisture into the air. Filtered models are evaporative and use a fan to put humidified air into the room. Filter-free models put a visible mist directly into the air.

Maintenance and care

All humidifiers, whether warm or cool, filtered or filter-free, require regular cleaning and maintenance. Before you buy, take a look at the models you’re considering and think about how easy they might be to clean. Do they have detachable parts that can be placed in a dishwasher? Are there narrow openings that might be difficult to clean? You’ll need to wipe down the inside of the tank regularly, so make sure the humidifier you choose has an opening large enough to reach inside.

The cleaning process will vary depending on the model, but in general, it’s a two-step process that involves descaling and disinfecting. Descaling breaks down any minerals that may have accumulated on the humidifier. Disinfecting will kill any germs that have built up. You’ll need bleach for disinfecting, vinegar for descaling, plus a cloth or brush. Follow the cleaning instructions in your humidifier’s use and care manual.

Keeping the humidifier clean is even more important if you’re using it to ease a cold, allergies or asthma, as a dirty dehumidifier can put contaminants back into the air.

Humidifiers are not diffusers

Humidifiers are sometimes confused with essential oil diffusers, but the two are not interchangeable. Diffusers tend to be much smaller than humidifiers and are designed to accommodate oils. Humidifiers can only be filled with water. Oils or other substances can damage the humidifier’s tank and mechanical parts.

Tips for Choosing the Ideal Portable Room Air Cleaner


Portable room air cleaners represent the quickest, most accessible option for improving indoor air quality in homes, classrooms, and offices. They work by filtering out harmful particles from the air like dust, pollen, tobacco smoke, mold spores, bacteria, viruses, and more. By removing these pollutants, air cleaners can significantly improve indoor air quality. 

But with so many models to choose from, it can be challenging to decide what you need from an air cleaner. That’s why we’re breaking down the buying process.  

When selecting an air cleaner, consider the following factors: 

  • Room size: Ensuring the air cleaner is capable of effectively covering the size of the room is the most important feature to look for. Check the manufacturer’s specifications for the recommended room size. EPA recommends looking for air purifier models that provide at least 4.8 ACH for the recommended room size to help improve your indoor air quality
  • Type of Filter: Learn what type of filter the air cleaner uses, including its capabilities and required maintenance.  
  • Clean Air Delivery Rate (CADR): CADR, which is AHAM’s rating system for an air cleaner’s efficacy, provides a way to choose an air cleaner based on your specific air cleaning needs. CADR is a measurement of how fast an air cleaner filters three commonly sized particulates: dust, pollen and tobacco smoke. Follow the “two-thirds” rule and choose an air cleaner with a smoke CADR rating that is two-thirds the size of the room’s area. That means a room that is 200 square feet would require an air cleaner with a smoke CADR of at least 132. If you live in an area with a high pollen count, consider air cleaners with higher ratings for filtering pollen. If dust is an issue, pay closer attention to the unit’s rating for dust. And if you have smokers in the home, look for higher ratings for smoke. If you are using an air cleaner to address wildfire smoke, AHAM recommends a model with a smoke CADR equal to the size of the room in square feet. The higher the CADR number for each pollutant, the faster the unit filters the air. AHAM considers CADR the most important metric for comparing air cleaner performance. 
  • Noise level: This is related to room size. Choosing an air cleaner properly sized for the space is the best way to ensure that the noise level is appropriate.  
  • Look for the AHAM Verifide seal: The mark can typically be found on product packaging and means the manufacturer’s claims have been independently verified through rigorous testing. (learn more about AHAM Verifide below). 

ABOUT AHAM VERIFIDE 

Not all portable room air cleaners are the same. When you’re ready to purchase an air cleaner, always look for the AHAM Verifide® mark. Room air cleaners certified through the AHAM Verifide program have been rigorously tested by an independent laboratory to ensure the product will perform to the manufacturer’s product claims for the suggested room size. The AHAM Verifide mark can be found on product packaging.  

To find AHAM Verifide® room air cleaners, use AHAM’s online searchable directory to locate the model that’s right for you. 

Find a Certified Room Air Cleaner Here 

The ABCs of IAQ: A Guide to Understanding Indoor Air Quality Terms

Given that most people spend 90 percent of their time indoors, indoor air quality (IAQ) is an important aspect of our comfort and well-being at home and at work. Yet understanding IAQ can be a bit overwhelming — especially given all the science, measurements, and acronyms associated with it. Let’s take a deeper look at the ABCs of indoor air quality and the terms and acronyms you might run across when looking for solutions to improve your indoor air.

IAQ: INDOOR AIR QUALITY

Indoor air quality (IAQ) refers to the quality of air in homes or other buildings, especially as it relates to the health and comfort of the occupants. It encompasses a variety of factors including pollutant levels, humidity and ventilation. Good indoor air quality is essential for maintaining a healthy indoor environment, especially in places where people spend a large portion of their time, like homes, offices, and schools.

According to the Environmental Protection Agency (EPA), levels of indoor pollutants can be two to five times—and occasionally more than 100 times — higher than outdoor levels due to dust, allergens, smoke, pet dander, mold, bacteria, respiratory viruses, and more.  Key factors influencing indoor air quality include:

  1. Pollutants: These can come from a variety of sources:
    • Biological contaminants such as mold, dust mites, pollen, and pet dander.
    • Chemical pollutants from household cleaning products, paints, building materials or combustion byproducts.
    • Particulate matter (PM), which are small particles from dust, smoke or vehicle emissions can also accumulate indoors (learn more below).
  2. Ventilation: Poor ventilation can lead to a build-up of indoor pollutants. Proper ventilation, either through mechanical systems or open windows, is crucial for maintaining good air quality.
  3. Humidity: Excess humidity can encourage mold growth, while very low humidity can lead to dry skin and respiratory issues.

Improving IAQ involves proper ventilation, minimizing sources of pollutants, using air cleaners, and maintaining appropriate humidity levels.

CADR: CLEAN AIR DELIVERY RATE

AHAM’s standard for measuring an air cleaner’s efficacy is called the Clean Air Delivery Rate (CADR). Similar to ACH, CADR indicates the volume of filtered air an air cleaner delivers, with separate scores for tobacco smoke, pollen and dust. The higher the CADR number for each pollutant, the faster the unit filters the air.

As a rule of thumb, the CADR of an air cleaner should be equal to at least two-thirds of the room’s area. For example, a 10-foot by 12-foot room has an area of 120 square feet. It would be best to have an air cleaner with a smoke CADR of at least 80. If you are using an air cleaner to manage wildfire smoke, AHAM recommends a smoke CADR equal to the size of the room in square feet.

Using an air cleaner with a higher CADR in that room will simply clean the air more often and faster. If your ceilings are higher than 8 feet, an air cleaner rated for a larger room will be necessary.

ACH: AIR CHANGES PER HOUR

Air changes per hour (ACH) is a key metric for air cleaners that refers to the number of times the entire volume of air in a room is filtered or replaced by the air cleaner within one hour.

ACH is calculated by dividing the volume of air the room air cleaner can process in an hour by the volume of the room. For example, if an air cleaner can process 400 cubic feet of air per minute (CFM), it would process 24,000 cubic feet of air per hour (400 CFM x 60 minutes). If the room has 6,000 cubic feet of air, the ACH would be 4, meaning the purifier can filter all the air in the room four times per hour.

The ACH value depends on the room size and the air cleaner’s capacity. An air cleaner that delivers 5 ACH in a small room might only provide 2 ACH in a larger room, so it’s important to choose an air purifier that matches the room size for optimal air cleaning efficiency. Per the AHAM AC-1 Standard, the suggested room size on the AHAM Verifide label is based on 4.8 ACH.  The U.S. Environmental Protection Agency (EPA) Office of Indoor Air Quality recommends 4.8 ACH.  IAQ researchers have found that the minimum ventilation recommendation is 3 ACH, and that more ventilation or air changes enhance indoor air quality.

PM: PARTICULATE MATTER

Particulate matter (PM), is a complex mixture of tiny particles and liquid droplets in the air. I tis measured in sizes, such as PM10 and PM2.5. PM10 includes things like dust, pollen, and mold, while PM2.5 includes combustion particles and organic compounds like smoke.

To put the physical size of PM into context, a human hair is about 50-70 micrometers in diameter, and a grain of fine beach sand is about 90 micrometers. PM10 is less than 10 micrometers, while PM2.5 is less than 2.5 micrometers.

HEPA: HIGH EFFICIENCY PARTICULATE AIR

High-efficiency particulate air (HEPA) filters are a type of air filter designed to trap very small particles from the air. To be classified as a HEPA filter, it must meet strict standards set by the U.S. Department of Energy, which require it to capture at least 99.97% of airborne particles as small as 0.3 microns in diameter. These particles include dust, pollen, mold spores, bacteria, and some viruses.

HEPA filters are made of a dense mat of fibers, usually composed of fiberglass, which create a maze-like structure that captures those harmful particles. They are included in a variety of household products, including some models of air cleaners and vacuums.

ABOUT AHAM VERIFIDE

Portable room air cleaners represent the quickest, most accessible option for improving indoor air quality. Air cleaners can filter out harmful particulates like tobacco smoke, dust, and pollen, making the air your family breathes cleaner and healthier.

But not all air cleaners are the same. When you’re ready to purchase an air cleaner, always look for the AHAM Verifide® mark. Room air cleaners certified through the AHAM Verifide program have been rigorously tested by an independent laboratory to ensure the product will perform to the manufacturer’s product claims for the suggested room size. The AHAM Verifide mark can be found on product packaging.

To find AHAM Verifide® room air cleaners, use AHAM’s online searchable directory to locate the model that’s right for you.

Button: Find a Certified Room Air Cleaner Here

HEPA Filters: What They Mean for Indoor Air Quality

Between indoor air pollutants and allergens like dust and pollen, PM 2.5, smoke from wildfires and illnesses like flu, COVID, RSV, and the common cold, there are plenty of reasons to pay more attention to indoor air quality. 

According to the U.S. Environmental Protection Agency (EPA), most people spend about 90 percent of their time indoors, where levels of pollutants can be two to five times higher than outdoors. Those levels of indoor air pollutants are of particular concern in the fall as it gets cooler, and people begin to spend even more time indoors. 

If you are looking for a room air cleaner or vacuum, you likely have come across the term ”HEPA.” HEPA stands for “high efficiency particulate air” and refers to a type of air filter designed to trap very small particles. To be classified as HEPA, the filter must meet strict U.S. Department of Energy standards, which require the filter to capture at least 99.97% of airborne particles as small as 0.3 microns in diameter. These particles include dust, pollen, mold spores, bacteria, and some viruses. 

HEPA filters are made of a dense mat of fibers, usually composed of fiberglass, which create a maze-like structure that captures particles through a combination of three mechanisms: 

  1. Interception: Particles following the airstream come into contact with the filter fibers and stick to them. 
  2. Impaction: Larger particles can’t follow the airstream around fibers and instead collide with them. 
  3. Diffusion: Smaller particles move erratically, increasing the chance they will hit a fiber and become trapped. 

HEPA filters can improve indoor air quality because they: 

  • Remove allergens and pollutants: HEPA filters can capture common indoor allergens like dust mites, pollen, pet dander, and mold spores, improving air quality for people with allergies or respiratory conditions. 
  • Capture harmful microorganisms: HEPA filters are capable of trapping illness-causing bacteria, viruses and mold.  
  • Reduce smoke and odors: HEPA filters can capture smoke particles, improving air quality in environments where tobacco smoke, wildfire smoke, or pollution is a concern. 

HEPA filters are included in a variety of household products designed to improve air quality and cleanliness. Some common types of products that utilize HEPA filters include: 

Air cleaners: Standalone portable room air cleaners are designed specifically to clean indoor air. They may use HEPA filters to trap dust, pollen, mold spores, pet dander, smoke, and other particles. If you live in an area affected by wildfires, or have tobacco smokers in the home, an air cleaner with a HEPA filter and activated carbon filter can also help reduce the smell of smoke in your home.  (Learn more about AHAM Verifide below.) 

Vacuums: HEPA-filtered vacuums prevent dust, allergens, and fine particles from being released back into the air while cleaning carpets, rugs, and floors. 

Home dehumidifiers with air filtration: Some dehumidifiers are equipped with HEPA filters, meaning they both reduce moisture and capture fine particles in the air. 

HEPA filters are particularly valuable in settings where maintaining clean, allergen-free air is important, such as homes with allergy sufferers or environments prone to airborne particles like smoke or dust. It is important to change HEPA filters according to the manufacturer’s recommendations.  

About AHAM Verifide 

Portable room air cleaners, also called air purifiers, represent the quickest, most accessible option for improving indoor air quality in the home. When you are ready to purchase an air cleaner, always look for the AHAM Verifide® mark. Room air cleaners certified through the AHAM Verifide program have been rigorously tested by an independent laboratory to ensure the product will perform to the manufacturer’s product claims for the suggested room size. AHAM’s standard for measuring an air cleaner’s efficacy is called the Clean Air Delivery Rate (CADR). CADR indicates the volume of filtered air an air cleaner delivers, with separate scores for tobacco smoke, pollen and dust. The higher the CADR number for each pollutant, the faster the unit filters the air. The AHAM Verifide mark can be found on product packaging.  

To find AHAM Verifide® room air cleaners, use AHAM’s online searchable directory to locate the model that is right for you. 

Find a Certified Room Air Cleaner Here

What is PM 2.5 and What Does it Mean for Indoor Air Quality?

Events like the COVID-19 pandemic and widespread wildfires in the U.S. and Canada have brought much-needed attention to the importance of indoor air quality (IAQ) and the critical need to improve the air we breathe. The good news is that there are several simple methods for reducing PM 2.5 and improving indoor air quality.

As more research on air quality is conducted, scientists are taking a deeper look at the impact of particulate matter (PM) on both indoor and outdoor air quality and its effect on human health. The science of particulate matter can be a bit daunting, so let’s put things in perspective. 

PM is a complex mixture of tiny particles and liquid droplets in the air. It is measured in sizes, such as PM10 and PM2.5. PM10 includes things like dust, pollen, and mold, while PM2.5 includes combustion particles and organic compounds like smoke. 

To put the physical size of PM into context, a human hair is about 50-70 micrometers in diameter, while fine beach sand is a little larger, at about 90 micrometers. PM10 is less than 10 micrometers, while PM2.5 is less than 2.5 micrometers. These are very tiny particles that are invisible to the naked eye.  

According to the National Institutes of Health (NIH), when it comes to the human respiratory system, PM10 particles can reach the upper airways and trachea, and can typically be eliminated by sneezing or simple nose blowing. But PM 2.5, also known as fine particles, has the potential to penetrate deep into the lungs and contribute to health problems.

PM 2.5 can enter indoor environments from outdoor sources such as vehicle emissions, industrial pollutants, and natural phenomena like wildfires. However, indoor activities contribute significantly to PM 2.5 levels as well. Common sources include: 

  • Cooking: Frying, baking, and grilling release fine particles into the air. 
  • Heating systems: Fireplaces and wood stoves can emit PM 2.5. 
  • Cigarette smoke: One of the most potent indoor sources of PM 2.5, affecting not just smokers but also those exposed to secondhand smoke. 
  • Candles and incense: Burning candles or incense can release fine particles into the air. 
  • Cleaning products: Certain aerosols and chemical cleaners release particulate matter when used indoors. 

The concentration of PM 2.5 indoors, where people spend about 90 percent of their time, can sometimes surpass outdoor levels, especially in poorly ventilated spaces. Cooking without proper ventilation or smoking indoors can rapidly increase PM 2.5 concentrations, negatively impacting the indoor air quality.   

So, what can you do to reduce PM 2.5 indoors? Monitoring PM 2.5 levels in indoor environments has become easier with the availability of affordable air quality monitors, which can provide real-time feedback on the concentration of fine particles, helping families or businesses take corrective measures. 

In addition, there are several ways to minimize exposure to PM 2.5, including: 

  1. Improve ventilation while cooking: An externally vented range hood is the best way to reduce cooking-related pollutants. Downdraft ranges and cooktops, over-the-range microwaves with built-in fans, ceiling fans and air cleaners can also reduce cooking-related pollution.  
  2. Use an air cleaner: Portable room air cleaners, also called air purifiers, represent the quickest, most accessible option for improving indoor air quality in the home. When you are ready to purchase an air cleaner, always look for the AHAM Verifide® mark (learn more about AHAM Verifide® below). 
  3. Avoid smoking indoors: Smoking indoors dramatically increases PM 2.5 levels. Ensuring homes and workplaces remain smoke-free is one of the most effective ways to reduce exposure. 
  4. Clean regularly: Dusting with damp cloths and vacuuming with HEPA filter-equipped vacuum cleaners can help reduce particulate matter buildup.
  5. Check real-time outdoor air quality levels: With a simple zip code search, you can get up-to-date air quality data for where you live (including levels of PM2.5 and 10) at www.airnow.gov.  

By understanding its sources, health risks, and methods of control, you can take practical steps to reduce PM 2.5 and improve the indoor air quality in your home.  

About AHAM Verifide® 

When you are ready to purchase an air cleaner, always look for the AHAM Verifide® mark. Room air cleaners certified through the AHAM Verifide® program have been rigorously tested by an independent laboratory to ensure the product will perform to the manufacturer’s product claims for the suggested room size. AHAM’s standard for measuring an air cleaner’s efficacy is called the Clean Air Delivery Rate (CADR). CADR indicates the volume of filtered air an air cleaner delivers, with separate scores for tobacco smoke, pollen and dust. The higher the CADR number for each pollutant, the faster the unit filters the air. The AHAM Verifide mark can be found on product packaging.  

To find AHAM Verifide® room air cleaners, use AHAM’s online searchable directory to locate the model that is right for you. 

Find a Certified Room Air Cleaner Here 

Respiratory Illnesses, Fall Allergies Put Indoor Air Quality in Focus

If indoor air quality had a season, fall might be it. With millions of children across the U.S. and Canada now back in school, multiple indoor air quality concerns are on the minds of parents, educators and others. Those include new COVID variants, fall allergies, and the spread of illnesses like colds and the flu.

While there’s no way to completely avoid illness-causing viruses and bacteria, there are ways to reduce the risk of indoor transmission. Portable room air cleaners represent the quickest, most accessible option for consumers who want to improve the indoor air quality in their home or classroom. Testing has shown that room air cleaners with HEPA filters have the ability to reduce the level of viruses, bacteria and mold in indoor air. The U.S. Environmental Protection Agency has said that, when used properly, air cleaners can help reduce airborne pollutants, including viruses.

Indoor air quality gained prominence as a public health issue during the  the COVID-19 pandemic, and many have made room air cleaners an important part of their plan to reduce the chance of transmission. Almost half (46%) who responded to an AHAM survey conducted in late 2020 said they had taken steps to improve their home’s indoor air quality during the pandemic. Another 16% reported having purchased an air cleaner during the pandemic. Among those who owned a portable air cleaner, 42% reported using it more than they had prior to the pandemic.

In addition to viruses and illness, many consumers also reported being concerned about pollutants like dust, mold and pollen.

There will soon be an easy way to compare the ability of different air cleaner models to remove viruses, bacteria and mold. AHAM has developed a room air cleaner standard that measures removal of microbiological pollutants like viruses, bacteria and mold. The standard, AHAM-AC-5-2022, is accredited by the American National Standards Institute (ANSI) and will ultimately be added to AHAM’s Clean Air Delivery Rate (CADR), which assigns numerical ratings based on an air cleaner’s tested performance in a given room size.

AHAM AC-5 was developed over 18 months by a team of public health professionals, engineers and academic researchers.

Room air cleaner use tips

  • Air cleaners should be positioned as close as possible to the center of the room to maximize airflow.
  • Change the air cleaner filter regularly, according to the model’s use and care manual.
  • Use a vacuum with a HEPA filter regularly to remove pollutants that could potentially be put back into the air.

Back to School: Why Air Cleaners are an Essential Tool for a Healthy Classroom

Pencils are sharpened and backpacks are filled. School is back in session, and teachers, students, and parents are hopeful for the best year yet! In addition to those long lists of school supplies, there’s one often-overlooked tool that should be on every classroom’s checklist: a portable air cleaner. 

While most people are aware that outdoor air pollution can impact their health, poor indoor air quality (IAQ) can also have significant and harmful health effects. IAQ is a real concern as students head back to the classroom—especially considering fall allergies, illnesses like the common cold and the flu, and new COVID variants.  

According to the Environmental Protection Agency (EPA), most people spend about 90 percent of their time indoors where levels of pollutants can be two to five times—and occasionally more than 100 times—higher than outdoor levels due to dust, allergens, bacteria, viruses, and more.  These levels of indoor air pollutants are of particular concern in classrooms, where students and teachers are in close quarters for several hours each day.  

The Importance of Clean Air in Schools 

The quality of the air we breathe significantly impacts our health, concentration, and overall well-being. For students, who spend a considerable amount of their day in the classroom, breathing clean air is crucial. Poor indoor air quality can lead to:   

  • Increased absenteeism: Exposure to allergens and pollutants can cause respiratory issues, leading to more sick days. 
  • Reduced concentration and learning: Stuffy, polluted air can make students feel lethargic, impacting their ability to focus and learn. 
  • Aggravated asthma and allergies: For students with asthma or allergies, poor air quality can trigger symptoms, affecting their comfort and safety.

How Air Cleaners Make a Difference 

While there’s no way to completely avoid illness-causing viruses and bacteria, there are ways to reduce the risk of indoor transmission. Portable room air cleaners are the quickest, most accessible option for improving indoor air quality in the classroom.  

Air cleaners, also known as air purifiers, work by filtering out harmful particles including dust, pollen, mold spores, bacteria, and viruses from the air. By removing these pollutants, air cleaners can significantly improve the air quality in classrooms, creating a healthier and more conducive learning environment. 

Choosing the Right Air Cleaner for Your Classroom 

When selecting an air cleaner for a classroom, consider the following factors: 

  • Size of the room: Ensure the air cleaner is capable of effectively covering the size of the classroom. Check the manufacturer’s specifications for the recommended room size.
  • Noise level: Since classrooms need to be quiet for effective learning, choose a model that operates quietly to avoid distractions. 
  • Maintenance: Opt for air cleaners that are easy to maintain, with filters that are simple to replace. 

Tips for Getting the Most out of Your Air Cleaner 

  • Air cleaners should be positioned as close as possible to the center of the room to maximize airflow. 
  • Change the air cleaner filter regularly, according to the model’s use and care instructions. 

Other Ways to Maximize Indoor Air Quality in the Classroom 

In addition to using air cleaners, here are a few other ways to improve indoor air quality: 

  1. Open windows: Whenever possible, open windows to allow fresh air to circulate and reduce indoor pollutants. 
  2. Regular cleaning: Dust and clean surfaces regularly to prevent the buildup of allergens. 
  3. Avoid harsh chemicals: Use non-toxic cleaning products to minimize the release of harmful fumes. 
  4. Limit the use of carpets and rugs: Carpets can trap dust and allergens. If possible, opt for hard flooring that’s easier to clean. 
  5. Vacuum frequently: Use a vacuum with a HEPA filter regularly to remove pollutants that could potentially end up back in the inside air. 

Let’s prioritize the health and well-being of students and teachers in the new school year. By adding air cleaners to the classroom, we can provide a cleaner, healthier environment that supports learning and growth.  

AHAM Verifide ® 

When you’re ready to purchase an air cleaner for the classroom, always look for the AHAM Verifide® mark. Room air cleaners certified through the AHAM Verifide program have been rigorously tested by an independent laboratory to ensure the product will perform to the manufacturer’s claims for the suggested room size. AHAM’s standard for measuring an air cleaner’s efficacy is called the Clean Air Delivery Rate (CADR). CADR indicates the volume of filtered air an air cleaner delivers, with separate scores for tobacco smoke, pollen and dust. The higher the CADR number for each pollutant, the faster the unit filters the air. The AHAM Verifide mark can be found on product packaging.  

To find AHAM Verifide® room air cleaners, use AHAM’s online searchable directory to locate the model that’s right for you. 

Find a Certified Room Air Cleaner Here 

Bring New Culture to Your Kitchen on July 4: Advice from a Professional Chef


What is on your Independence Day menu this year? Of course, you can go with the traditional hot dogs and hamburgers, cooked on an outdoor grill. Holidays have a way of triggering cravings for those familiar favorites. But maybe this is the year you try something different, a new dish, or a twist on the traditional. 

So where should a home cook look for inspiration? Stepping outside of the July 4th barbecue box and exploring new culinary landscapes can be intimidating, and it helps to have a little guidance. We caught up with Chef TJ Delle Donne, assistant dean and associate instructor for the Johnson & Wales College of Food Innovation & Technology, for some advice. Delle Donne has cooked on some big stages, including serving as chef de cuisine at the 90th birthday celebrations of both former President George H.W. Bush and former First Lady Barbara Bush. He shared his thoughts on how you can prepare and try some new cultural flavors this Independence Day.   

Get inspired 

New culinary adventures aren’t just for professional chefs. If you are looking to explore new and unfamiliar cuisines, solid research and development is the key, Delle Donne says. That’s available to everyone. “Take out a cookbook you haven’t seen in a while. Blow the dust off, look inside and see if you get inspired,” he says. Is it time to recreate the incredible meal you had on vacation? “A lot of times, it’s putting something you had—maybe Korean street tacos you had on a trip out West. Go down the rabbit hole on a Google search and see what inspires you.” 

Sometimes you can find inspiration in your own family. And food may be the best way to connect with a new culture “That’s the beauty of this country—we’re a cultural mosaic,” Delle Donne says. “Sometimes, you can find it in your circle. You have to be inquisitive and open your mind a little. If it is not your family, it might be your colleagues, your friends. Say ‘Tell me about how your family ate in Ghana, or Turks and Caicos. Tell me about your Mexican heritage, your Canadian heritage.’” Or the cultural inspiration may be closer to home. “If they’re from Kentucky, they must have a macaroni-and-cheese recipe in their repertoire. Everyone wants to introduce you to their culture through food. It’s an international language.” 

While the flavors may be new, you likely will recognize the cooking techniques – and the appliances – that you’ll use to bring the dishes to life.  

“Grilling in Japan is the same as grilling in Kentucky,” Delle Donne says. “Roasting in France is the same as roasting in Virginia. Don’t be intimidated by braising, roasting, sauteing, grilling, broiling. It’s the same technique. It’s just the pantry that changes.” 

And you might be surprised by the similarities to your regular menu, even on the Fourth of July. “If you go to England or Ireland, those ingredients look a lot like our ingredients—potatoes, sausage. The hot dog is obviously from the migration of the Polish and German population.” 

If you are looking for quick inspiration, Delle Donne had a few suggestions on some that might be a good fit for an Independence Day feast:

Elote salad: Instead of eating traditional corn on the cob, take it off the cob for a twist on grilled Mexican street corn.

Shawarma station: This involves marinating, grilling and slicing. Line up the flatbreads and toppings and have people build their own.

Ramen bar: Put the hot broth in a coffee percolator, then make a station with noodles, hardboiled eggs, mushroom, seaweed and other ingredients.

Hot dog variations: “Every culture does ground meat in a casing,” Delle Donne says. “Maybe do kielbasa, or bratwurst, or knackwurst.” 

Build-your-own pizza: This might work best with an indoor pizza oven. “This is always fun for the kids. Neapolitan-style pizzas is a cool way to get some Italian flair into the Fourth of July,” Delle Donne says.

Others that might hit the spot on the Fourth are birria (Mexican beef stew), tandoori chicken or braised beef tacos.

Once you have chosen your menu, it’s time to collect the ingredients. “Highlight or pull out any ingredients that you might not be able to get at your local grocery store and see where you can find them. “Is it a Latin or Korean grocery store? See where you can find them and have fun with the whole process. Cooking is an art form that should alleviate stress.” 

Appliances for the “cook-in” 

While the Fourth of July is synonymous with outdoor cooking, the kitchen offers plenty of advantages. Home cooks sometimes don’t use tools like a broiler, Delle Donne says. “They use it to store pots and pans and don’t realize it can give you flame-broiled food. It’s a fantastic resource for cooking indoors.” If you are trying new dishes, it is important to use the right tools. “If you’re making tandoori chicken and it calls for a clay pot, get a clay pot. That’s how you get the most authentic flavor profiles,” Delle Donne says. Don’t be afraid of deep frying, either. “Deep fryers are safe and they’re fun. A lot of people who want a frite, or a French fry, or a tot, they try to bake them, and it doesn’t come out the way they expect. Deep frying is a technique, and it’s the best for crispy food.” 

Make ventilation a priority


You don’t have to worry about ventilation when cooking outside. If you are cooking inside and you have a ventilation hood, turn it on. Ventilation is an important and sometimes overlooked aspect of the cooking process. It is the solution to manage cooking byproducts like smoke, steam and grease.  

“Ventilation is probably one of the most important parts of cooking,” Delle Donne says. “If I were building a kitchen in my home, in a school, in a restaurant, it’s one of the first things I would think about. Any food is full of water or fat, and that creates steam or smoke. It’s going to happen.” 

Ventilation is also the best way to manage cooking-related odors and improve indoor air quality. “You don’t want to breathe in any smoke or grease particles. Getting it out of your house is paramount. Turn the hood on.” Don’t worry, you still have many good options for improving ventilation while cooking, even if you don’t have a ventilation hood. 

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