I can smell dog fur when I vacuum the carpet. This means my vacuum cleaner is sucking in dog fur, and then shooting some of it back into the air! I am a senior citizen. Vacuuming is too much work to put up with this mess. Should I get a certified vacuum cleaner and a certified air cleaner?
More important than certification is whether a vacuum or air cleaner uses a real HEPA filter. Certification will help you distinguish real from fake HEPA. Certification will help you find cleaners that properly test the air. But certification won’t guarantee you’ll get a good vacuum cleaner. I found that the certified air cleaners tend to be good machines. The certified vacuum cleaners did not tend to be good machines.
This is my personal opinion as a senior with allergies, living independently in my home. I want great features, but I also insist on reliability and good customer service.
This is Allergies Part II. Click here for Allergies, Part I.
All certified air purifiers and vacuum cleaners use HEPA filters. I want a HEPA device from a company I trust. I like the companies making the certified HEPA air cleaners. I’m not as fond of the companies making certified HEPA vacuum cleaners.
All Certified Cleaners Use HEPA
The asthma & allergy friendly® certification says that a device such as an air cleaner or vacuum cleaner has met minimum effectiveness standards. These include the use of true HEPA technology.
HEPA filters hold onto particles as small as 0.3 microns 99.97% of the time. Using HEPA, I should not be able to smell dog fur when I vacuum.
I was not aware of the certification availability when I researched air cleaners for What is the Best Allergy Device for Seniors? Part I: Air Cleaners (click here to read it on SeniorHomeGuide). So in this article, I’ll show you how certification works for both air cleaners and vacuum cleaners.
The Elderly’s Allergies are More Annoying
About 50 million Americans have allergies, according to Allergy Standards. Symptoms can be worse for independent seniors who stay indoors. Some indoor pollutants are up to 5 times more concentrated indoors than outside.
Because our organs change and weaken as we grow older, the allergy symptoms hit us harder. The “weaking of septal cartilage and a loss of nasal tip support may decrease nasal airflow leading to exacerbation of nasal obstruction, complaints commonly seen in geriatric rhinitis patients” (source).
In plain terms? Airborne allergens irritate senior noses more than younger ones. We need to combat the allergens in the air, carpets and furniture.
Removing allergens can make a huge difference to senior allergen symptoms.
Where the Allergies Are
McAllen, TX is the Allergy Capital of America. It ranks with Jackson, Mississippi; Providence, Rhode Island; Memphis, Tennessee; and Springfield, Massachusetts in the top five Allergy Capitals, according to the Asthma and Allergy Foundation of America (AAFA) (source).
People age 65 or older in these cities ranges from 9.6% to 12.4%.
About 10% of these polluted cities are seniors. I look at it this way. If you’re a senior living in an area with lots of allergens, then this affects 100% of your home’s senior population.
The high pollen and pollution in these cities affects the older populations more. Typical allergy symptoms include runny nose, sneezing and itching.
The AAFA suggests people with allergies use medicines to relieve their symptoms. These include antihistamines, decongestants, and nasal corticosteroids, according to the Mayo Clinic.
I have been on multiple allergy medicines, and I’m personally not fond of them. You know what works great though? A warm washcloth! Wiping the allergens off the eyes, nose and mouth really helps keep my symptoms down.
That’s because a washcloth cleans away the allergies on the face. It’s the cleaning that prevents the allergy symptoms in the first place. Likewise, the vacuum and air cleaning helps prevent allergy attacks.
HEPA is the Particulate Cleaning Gold Standard
HEPA is High Efficiency Particulate Air. The “A” also stands for Absorbing and Arrestance, depending on which organization you ask. HEPA is a filtration standard. A HEPA filter “can remove the majority of harmful particles, including mold spores, dust, dust mites, pet dander, and other irritating agents,” according to the U.S. National Library of Medicine (read more here).
The purpose of a HEPA filter in an air cleaner and a vacuum cleaner is to prevent dirty air from shooting out back into the room. The more the filter holds onto, the cleaner your house will be.
Allergy Device Standards
Because manufactures were selling HEPA “like” and HEPA “type” filters, the Asthma and Allergy Foundation of America created a new standard for air cleaners and vacuum performance.
Manufacturers volunteer their products for certification. They pay a fee for the tests, and get marketing support in return. So the test ratings are not 100% altruistic. Short of Consumer Reports and the National Highway Safety Administration, we have to settle for a bias, which is small in this case.
Along with Allergy Standards Limited (ASL), the AAFA created scientific standards for the allergy industry.
“Any company can label their products as ‘hypoallergenic’ or ‘allergy-friendly’ with no proof to back up those claims.” The “asthma & allergy friendly®” certification program “tests and certifies products and services to improve the air quality and health of homes,” says the Asthma and Allergy Friendly website.
Whole Home Allergy Proofing
The Mayo Clinic advises treating the whole home for allergens. They advise avoiding wood-burning fireplaces. Put the dog and cat outside “weather permitting,” according to their advice. If you love your dogs and cats as much as I do, you know this is a silly idea. I am allergic to my cat. He is right next to me as I write this. I wouldn’t dream of putting him outside unless he wanted to go outside.
But the list is helpful (you can read it here) to remember to think about bedding options, which household objects foster mold growth. They recommend using a HEPA filtered vacuum cleaner.
Household Chemical Pollutants
If you’ve had allergy tests then you probably know what is causing your allergy symptoms. It is possible that you have new allergies, or need allergy tests. If you are feeling allergic and don’t know why, here are some common household allergens.
Chemical allergens include:
- paint gives of volatile organic compounds (VOCs)
- flooring traps dust and sometimes contains phthalates and other irritating compounds
- cleaning products contain irritants such as bleach, surfactants and preservatives
- tobacco smoke, not technically an allergen, but can cause huge respiratory problems
- asbestos is in products built before 1970 and is often still found in homes
Then there are biological allergens, stuff like mold. These allergens are alive. Get rid of them to create an allergy-friendly home.
Biological allergens include:
- animal dander
- house dust mite
asthma & allergy friendly® Certified Air Cleaners
I wanted to see what features we would find in asthma & allergy friendly® certified air cleaners. The certified air cleaners have certain filters in common. The purifiers all clean these allergens using HEPA to capture the tiniest particles:
- Tobacco Smoke
To pass certification tests, the air cleaner has to do the following (read the certification standards here):
- They remove bio hazards
- They don’t just push those bio hazards back out into the air
- Air cleaners that monitor ozone in the air do so accurately
Important Air Cleaner Features
What do you need to look for when shopping for an air cleaner?
Air Cleaner Size
All air cleaners treat a certain amount of square feet of air. You need to know the square footage of the area you are cleaning to buy a cleaner appropriately sized for the situation. Air cleaners cannot work through walls, and have a hard time with doors. The machine will clean the air within a walled space.
The right size is important. If you get a machine that is too weak, it will not clean the air of allergens. If you get one that is too strong, it will waste electricity.
Air Cleaner Wall Mount
Some air filters come with wall mount kits. A good carpenter can construct a wall-mount solution for you as well. Always be careful to ensure that the air cleaner has space around the air inlet and outlet.
Air Cleaner Filters
All certified air cleaners have at least one filter that meets the HEPA standard.
Air filters can capture cold and flu germs. Germs can grow on filters. Prevent this mess with antimicrobial-coated filters. Look for filters with antimicrobial coatings.
You can wash and re-use washable filters. Otherwise, you must throw away a filter and replace with a fresh one.
Air Cleaner Negative Ion Generators
Many certified air purifiers come standard with “negative ion generators.”
The use of negative ion generators is controversial. The purpose is good but the result can be bad, especially for people with asthma.
A negative ion generator changes the electric charge in the air. The charged molecules can attract pollution molecules, making them heavy enough to fall to the ground.
The problem with negative ion generators is not with the ions. The generators can output ozone, which is harmful to the lungs.
Negative ions are not harmful. At worst, negative ions have no effect on lung function, according to the Journal of Negative Results in Biomedicine. At best, negative ions are useful as therapy for depression and anger, according to Oregon State University.
There is no controversy about breathing ozone. It is a bad idea and you should avoid it.
Whether ozone harms your health depends on the quantity you breathe. “There is no debate about the negative effect of ozone,” says the American Academy of Allergy Asthma & Immunology. “Ozone has clearly detrimental health effects if levels exceed 0.1 ppm as a daily average.”
Air Cleaner Sleep Mode
Sleep mode dims the unit’s lights when it’s dark. Some sense darkness and dim automatically. Others have a button that allows you to dim the lights. There are air cleaners that do not have a sleep mode. If you use these in a bedroom, be prepared to put thick, black tape over the unit’s lights.
Air Cleaner Noise Level
Noise level becomes important when the air cleaner’s noise interrupts conversation, television, or sleep.
Certified air cleaners studied for this article range between 20 and 60 dB. You can always keep an air cleaner quieter by using lower settings. If you want to use high power, how much noise will the unit put out? Will it interrupt sleep or conversation?
Based on personal experience and using Industrial Control dB examples, acceptable sound tops out around 60 dB. This is the level of “Conversation in restaurant, office, background music, or an air conditioning unit at 100 feet.”
Fifty dB is about the noise level of “a quiet suburb, conversation at home, or large electrical transformers at 100 feet.”
Forty dB is a bird song, or the level of a quiet library.
Thirty dB is a quiet, rural area.
Twenty dB is rustling leaves.
Air Cleaner Air Sensor
The air sensor feature tests the air quality for dust and particulates. Some test for cold and flu germs. When the test returns positive, the machine ramps up its speed. It continues to sample the air until the tests come back clean. The machine then slows its fan speed back down.
Air Cleaner Wireless App
Some air purifiers include wireless apps that run on a phone or tablet. Anything you can do at the machine’s interface, you can do remotely from the comfort of your phone.
Air Cleaner Warranty
The certified air cleaner units examined in this article have warranties ranging from one to 5 years.
Comparing Some Certified Air Cleaners
The table below contains data on some certified air cleaners. We go into more depth on the RabbitAir, AeraMax™ and Dyson air cleaners below that.
|RabbitAir MinusA2 SPA-780A Air Cleaner|
|6 stages of purification|
|Pre-filter is washable|
|20.8 to 45.6 DB (quiet)|
|AeraMax® 300 Air Cleaner|
|4 stage of purification and deodorization|
|Pre-filter is washable|
|39 to 64 db.|
|negative ion generator|
|Dyson Pure Cool Tower Air Cleaner|
|Pre-filter is washable|
|LG PuriCare Air Cleaner|
|Pre-filter is washable|
|23 to 51 db.|
The RabbitAir MinusA2 Certified Air Cleaner
Which brings us to our first asthma & allergy friendly® certified air cleaner, the RabbitAir MinusA2 780A.
RabbitAir MinusA2 780A Size
The RabbitAir MinusA2 780A cleans up to 815 square feet of space. So long as that space is contiguous (not blocked with walls or doors).
RabbitAir MinusA2 780A Filters
With five filters, the 780A seriously filters the air.
The pre-filter catches dust mites, pet hair and pollen.
The medium filter captures bacteria, dander, mold & fungi.
The proprietary BioGS filter “reduces the growth of bacteria and viruses on the filter.” I think that’s an important point. What do other air filters do about the bacteria and viruses caught in their filters? The BioGS also captures cooking odors, exhaust fumes, and virus-carrying particles.
You choose the fourth filter when purchasing the MinusA2. The choices are Germ Defense, Toxin Absorber, Pet Allergy, or Odor Remover. The machine already handles these contaminants. The extra filter adds that much more protection.
RabbitAir recommends the Germ Defense filter for elderly people.
“The Germ Defense filter is specially engineered to trap and reduce bacteria, mold and particles that carry viruses. This filter is perfect for children, elderly people, and those with compromised immune systems who are most sensitive to particles in the air.”
The activated carbon charcoal filter traps household odors, tobacco smoke, and VOCs (volatile organic compounds).
RabbitAir MinusA2 780A Wall Mount
The RabbitAir MinusA2 780A also comes with a wall mount kit (sometimes extra, sometimes included, depending on the store). I love the idea of getting anything and everything off counters and the floor. You can optionally mount the RabbitAir on the wall.
RabbitAir MinusA2 780A Negative Ions
I reached out to RabbitAir, maker of the asthma & allergy friendly® certified MinusA2 air purifier.
“Isn’t ozone harmful?” I asked. “Doesn’t the negative ion generator produce ozone?”
The RabbitAir customer service representative replied.
She said that RabbitAir air cleaners have no (zero) ozone emission when off. They have tiny ozone emission when on low speed. And none on higher speeds.
On low speed, the ion generator produces 0.002-ppm maximum ozone concentration, RabbitAir said.
“That is 25 times less than the 0.05 ppm maximum ozone concentration safety standard set for by the California Air Resource Board.”
It is also 50 times less than the 0.1-ppm harmful level cited in the American Academy of Allergy Asthma & Immunology article.
The RabbitAir rep said they had no data proving the ion generator cleaned the room better.
Therefore, if you get a MinusA2 from RabbitAir, you can leave the negative ion generator off; or run it at anything but low speed to produce zero ozone.
The 780A has an automatic dark mode, which lowers the machine lights when it is in a dark room.
RabbitAir MinusA2 780A Noise Level
The stated noise is 20.8 to 45.6 dB. Forty-five dB is between a birdcall and home conversation, according to Industrial Noise Control’s website.
RabbitAir MinusA2 780A Air Sensor
In automatic mode, the 780A’s particle sensor modifies the fan speed. It tests every 15 minutes until the air is clean. Then it slows the fan down again.
RabbitAir MinusA2 780A Wireless App
You can control the 780A through a wireless app on your phone or tablet.
RabbitAir MinusA2 780A Warranty
The unit has a five-year warranty.
View the RabbitAir MinusA2 780A on Amazon
Eleven AeraMax™ Certified Air Cleaners
AeraMax is a Fellowes brand. Fellowes is a huge office supply company. AeraMax offers eleven asthma & allergy friendly® certified air cleaners.
In general, AeraMax™ models are their minimum air cleaning size. For example, AeraMax™ 300 cleans from 300 to 600 square feet.
All AeraMax air cleaners have four filters treated with antimicrobial coatings. This prevents the biological particulates from growing in the filter.
The carbon filter cleans odors and cigarette smoke.
The True HEPA filter removes ragweed, viruses, germs, dust, mites, mold, pet dander and smoke.
AeraMax™ Wall Mount
AeraMax™ consumer air purifiers do not come with wall mounts.
AeraMax™ Negative Ions
AeraMax™ calls its negative ion generator PlasmaTRUE Technology that “creates an ionized field to help safely remove airborne particles.” According to their FAQ, the AeraMax™ machines create 4.0 ppb (parts per billion) ozone.
AeraMax™’s ozone numbers are in parts per billion, where RabbitAir’s were in parts per million. To judge apples to apples:
RabbitAir’s low speed setting emits a maximum of 2 ppb. AeraMax™ emits a maximum of 4 ppb. The California standard sets a maximum of 50 ppb. The American Academy of Allergy Asthma & Immunology maximum is 100 ppb.
AeraMax™ Sleep Mode
AeraMax™ filters do not have a sleep mode.
AeraMax™ Noise Level
Noise ranges from about 39 to 64 dB, depending on model and speed. This is a quiet range.
AeraMax™ Air Sensor
All AeraMax™ filters have the AeraSmart™ sensor that detects air quality. When air quality goes negative, the AeraSmart™ increases the air clean fan speed. They monitor for both flu and cold viruses.
AeraMax™ Wireless App
AeraMax™ filters do not come with wireless app controls.
AeraMax™ guarantees consumer air filters for 3 years.
Five Dyson Certified Air Cleaners
I don’t feel qualified to comment on Dyson air cleaner technology. I don’t understand how they work. As long as we assume Dyson publishes their test results in good faith, their certified air cleaners effectively clean the air of dust, odors, and germs. Dyson advertises removal of all pollutants down to 0.3 microns with 99.97% efficiency. This is the HEPA standard.
In general, certified Dyson air cleaners have the following common features.
- They do not use fan blades to move the air.
- They have air sensor activation.
- They dim the display when you select nighttime mode.
- They respond to Echo and Amazon home devices.
- They are usually also cooling devices, heating devices, or both.
Dyson takes up such a huge portion of the certified air cleaner list, I want to make sure you can look at their air cleaners. Having said that, as you’ll see in the Vacuum Cleaner section below, I’m not a huge Dyson fan. Their customer service and quality reputation is not as good as I’d like.
You can check out the certified Dyson air cleaners on this article’s resource page here.
asthma & allergy friendly® Certified Vacuum Cleaners
Or, How I Got My Vacuum Cleaner Not to Smell like Dog Fur Anymore
Since my vacuum smells like dog fur, it must be blowing its bag back out into the air. Therefore, I decided it is time for a HEPA vacuum. To be extra safe, I am looking at certified HEPA vacuum cleaners.
The asthma & allergy friendly® vacuum cleaner certification ensures the vacuum you are buying meets the following specifications.
- The vacuum removes surface allergens
- It doesn’t increase airborne allergens
- It says one piece while working
- Emptying it shouldn’t cause more pollution
I always think of a good vacuum cleaner as having good suction. However, if it spits that sucked in material back into the air, then good suction will not matter. When a vacuum cleaner filter fails, the vacuum cleaner exhaust spits the dirt right back into the air.
What does matter is good suction AND retaining the sucked in particulates in the vacuum cleaner’s filter system. This is why HEPA is just as important to vacuum cleaner efficiency as it is to air cleaner efficiency.
Vacuum HEPA Holds Onto Dirt
High Efficiency Particulate Air (HEPA) filters collect “99.7 percent of all particles at 0.3 microns” or larger, according to the University of Illinois Extension.
The University of Illinois sets out five standards for an effective vacuum cleaner.
- It should be powerful, and completely sealed.
- It should have both an intake and an exhaust filter
- It should use only true HEPA filters, not HEPA-like or HEPA-type knockoffs.
The university recommends using an upright with a power nozzle vacuum cleaner, or a canister style vacuum cleaner, for carpets. They recommend a canister with a power nozzle vacuum cleaner for cleaning blinds, upholstery, and drapes.
Read their vacuum requirements list on their site.
Consumer Reports Tests Vacuum Cleaners
Consumer Reports rates vacuum cleaners for allergy sufferers (read their article here). They give their rankings for the five lowest emission vacuums on that link. I encourage you to get a Consumer Reports membership to read the 171 vacuum cleaner ratings. You want emissions to be low, but that is not the only criterion for rating a vacuum for helping relieve allergies.
asthma & allergy friendly® Vacuum Cleaner Standards
To pass the asthma & allergy friendly® certification tests, the vacuum cleaner must meet these standards:
The Dyson V8 Certified Vacuum Cleaner
The Dyson V8 is an asthma & allergy friendly® certified cordless stick vacuum. No cord means no tripping. As I’m “Mrs. Don’t Fall!,” I like removing trip hazards.
The cordless option means you do have to charge the battery between uses.
The Dyson V8 certified features include:
- it removes allergens
- it retains removed allergens, does not spit them back out into the air
- it still works great when partially full or full
- it’s easy to empty the vacuum without getting hit in the face with dirt
- it cleans hardwood floor crevices
- it monitors its filter’s effectiveness
The V8 Vacuum Filter
The filter is washable. This means you have to wash it (con), and it means you do not have to pay for new ones (pro). Of course, it is a HEPA system, as all certified vacuum cleaners include HEPA filtration.
The V8 Battery Use
When you run the Dyson V8 motorized cleaning head, you have 25 minutes of battery power. With the “direct drive cleaner head,” the battery lasts only 8 minutes. If you run neither power head, the vacuum battery will last 40 minutes.
I’m having a hard time picturing this being enough time. For example, I want a cordless stick vacuum to clean my staircase. There are 14 steps. The 25 head gives me less than 2 minutes per step. That’s probably reasonable. The 8-minute head gives me 34 seconds per step. That is not enough.
The V8 Dirt Bin
The dirt bin is 0.14 gallons. It’s large compared to the average vacuum bin. To empty it, you push a button while holding the bin over the trash. A mechanism shoots the contents downward, into the trash. Dyson advertises the bin release as “hands-free emptying.” If you’ve ever emptied a bagless vac, you know that the dust will fly upward. So this method is good. But you’re safer if you shoot it into a plastic bag wrapped up around your arms and vacuum bin. Capture as much of the dust as possible after it is ejected.
The V8 Carpet and Floor Effectiveness
The V8 cleans both floors and carpets. It senses the difference and self-adjusts. The stick disassembles into a giant handheld vacuum for cleaning chairs and couches.
Your Mileage May Vary with the Dyson V8 Stick Vaccum
Dyson has a contradictory reputation. I’ve seen some pretty angry complaints about their vacuums breaking. I’ve seen even angrier complaints about Dyson customer service not helping their customers.
Just off the top of my head, I think there might be a morale problem at Dyson. Just look at their vacuum cleaner documentation compared to their web marketing information. I’ve found at least three different values for how long the V8 battery lasts on each of the cleaner’s different power settings. I did not give you each variation because it is not relevant. It’s going to give you 30-40 minutes in normal mode. But the lack of attention to detail is concerning.
Most customers appear to love their Dyson V8. But there are many online reviewers who do not. They do not like the product reliability, or the company’s customer service.
So what to do?
A Non-Certified Stick Vacuum Floor-Only Alternative
While researching the Dyson V8 stick vacuum I ran across an incredibly popular knock off called the Moosoo Cordless 18KPA. Yes, it’s not certified. It has a good reputation among online reviewers. It weighs half what the Dyson weighs. The manufacturer claims the Moosoo has a 65 dB noise level. That’s quiet for a vacuum cleaner.
While this vacuum popped out at me as a potential winner, I discarded it from my list because it’s not for carpet cleaning. Its handheld version does not have a motorized head, so that’s two strikes against this specific model.
This is not the vacuum for me. I only described it because it helped me realize that vacuum cleaner certification might not be my guidepost. I will only buy from a company I trust. I will only buy a vacuum cleaner with the features I want.
You can find many worthy air purifiers in the certified listings. They all have great reputations, and superior HEPA filtration. They monitor the air for particulates and germs. If they find problems, they increase their fan speeds.
Vacuum cleaners, however, are not as good. So far, only Kenmore and Dyson are certified. I am not a huge fan of either brand.
I have a dog, a cat, and carpeting. For my next vacuum, I know I will get HEPA, but I’m not sure about the asthma & allergy friendly® certification.
When I do the analysis, I will post the results on Senior Home Guide, and link to them from here.
People Also Ask
Does pollution effect seniors more than younger people? Yes, seniors exposed to pollution have a higher risk of premature death than those not exposed to pollution. Even short term exposure is harmful. Read more at the Harvard School of Public Health site.
Products Mentioned in Allergy Articles
These are not endorsements.
- Levoit LV-PUR131 HEPA air cleaner
- Partu Air HEPA air cleaner
- RabbitAir MinusA2 780A HEPA certified air cleaner
- You can control the RabbitAir 780N HEPA with a wireless app
- AeraMax 300 HEPA certified air cleaner
- Dyson Pure Cool Tower TP04 HEPA certified air cleaner
- Hot Cool Tower HP04 HEPA certified air cleaner
- Hot Cool Link (Tower) HP02 HEPA certified air cleaner
- Cool Link Tower TP02 HEPA certified air cleaner
- Cool Link Desk DP04 HEPA certified air cleaner
- Dyson V7 Animal Cordless Stick HEPA vacuum cleaner
- Moosoo 17Kpa non-certified HEPA stick vacuum for carpets
- Moosoo 18Kpa non-certified HEPA stick vacuum for floors
Allergy Article References
- Why Get Certified?, Allergy Standards
- Allergic Diseases in the Elderly, Clinical & Translational Allergy, 2011
- Allergy Capitals Spring 2019, Asthma & Allergy Foundation of America
- US Census McAllen, TX
- US Census Jackson, MS
- US Census Providence, RI
- US Census, Memphis, TN
- US Census, Springfield, MA
- Dust Mite Allergy, Mayo Clinic
- HEPA Filter, US National Library of Medicine, , June 2019
- asthma & allergy friendly® Certification Program
- Asthma Canada
- Allergy Standards Limited
- asthma & allergy friendly®, About the Program
- Allergy Proof Your Home, Mayo Clinic, Sep 6, 2018
- asthma & allergy friendly® Certification Standards
- Air ions and respiratory function outcomes: a comprehensive review, Journal of Negative Results in Biomedicine, Sep 9, 2019
- High Intensity Negative Ion Generator, Oregon State University Student Affairs Counseling & Psychological Services
- Ozone & Negative Ion Generators, American Academy of Allergy, Asthma & Immunology, May 9, 2015
- Comparative Examples of Noise Levels, iac Acoustics
- RabbitAir BioGS Filter Features
- Healthy Indoor Air, University of Illinois Extension
- Best Vacuums for Allergy Sufferers, Consumer Reports, June 18, 2019
- Short-term exposure to low levels of air pollution linked with premature death among U.S. seniors, Harvard T.H. Chan School of Public Health, Dec. 26, 2017
Undated citations were retrieved October 18, 2019