It’s Coming From Inside the House

It’s Coming From Inside the House

10 surprising causes of indoor air pollution

February 25, 2021 | Published by O2

Air pollution is all around us. It’s in our streets, our cars, our workplaces, and even our homes. In a recent post, we explored the harmful impact it can have on the air we breathe indoors. In fact, most homes in Canada and the United States have poor indoor air quality. Some sources suggest that levels of indoor air pollutants may also have significantly increased as a result of the pandemic.

What causes the air quality in our homes to be so poor? Some of the biggest culprits are fairly obvious: secondhand smoke and wood-burning stoves are two conspicuous sources. Others, like candles, dander and hair from pets, cleaning products, and dust from carpets are less obvious, but make sense when you consider the impact they might have on your respiratory health.

But there are some sources that may completely surprise you. Here are ten of the most confounding causes of indoor air pollution.

1. Beauty and skincare products

When you’re lathering your scalp with shampoo in the morning, bleary eyed and focused on the day ahead, you probably aren’t thinking too much about the air pollution you’re creating just by washing your hair. As it turns out, beauty and skincare products emit many dangerous VOCs (volatile organic compounds) and are a major source of petrochemical pollution. One study from researchers at the University of Colorado at Boulder found that products like hairspray, skin lotion, shampoo, and other scented beauty products, may be contributing to ground-level ozone and PM2.5.

2. Hair Dryers

Once you’re done with your morning shower, you might decide to dry your hair with a hair dryer. Surprisingly, electric hair dryers are a common source of ultrafine particulate matter, or PM2.5. When you dry your hair in the morning, you might be blasting tiny particles 1/30th the width of a human hair all over, well, your hair. We know how harmful PM2.5 is to our health, so you might want to consider letting your hair air dry the next time you take a shower.

3. Humidifiers

As we move through the dry winter months, many of us have turned to humidifiers to maintain the moisture in our homes. In fact, an estimated 8 million humidifiers are sold in the US each year. They’ve been known to help relieve allergy symptoms, hydrate skin, and prevent dry, itchy eyes. But when used improperly and not cleaned regularly, humidifiers can emit significant amounts of mold into your home.

Ultrasonic humidifiers — which are much quieter than regular cool mist humidifiers — can also emit harmful levels of PM2.5 into the air. Ultrasonic humidifiers work by vibrating and breaking water into small droplets. These droplets are misted into the air and evaporate quickly, leaving  behind ultrafine particulate matter containing minerals and salts. This is why it’s important to always use distilled water in your humidifier.

4. Vacuum Cleaners

You may already know that carpets are major sources of allergens in the home, like dust mites, hair, pet dander, and mold. But your efforts to remove these harmful particles might be doing more harm than good. While it makes sense that sucking up them with a vacuum cleaner can help to remove them from your home, some of the dust and debris will simply be kicked up into the air. Vacuums also tend to be leaky, allowing some of the particles they suck up to escape and float around your home.

If you’re worried about what’s being kicked up by your vacuum cleaner, you may want to consider a HEPA vacuum, which captures “particulates of 0.3 microns with 99.97% efficiency,” and seals much better than a regular vacuum.

5. Microwave Popcorn

It’s another Saturday in quarantine, so you toss on a movie and settle down on the couch with a nice big bowl of microwave popcorn. It might seem like a healthier alternative to a bowl of chips or a plate of nachos, but it turns out that microwaving a bag of butter-flavoured popcorn emits high levels of — you guessed it — PM2.5.

Researchers from one University of California study found that microwave popcorn emitted 350-800 times more PM2.5 in the air than microwaving water. Next time you reach for that bowl of popcorn, you may want to consider making it on the stovetop – or do you?

6. Cooking

For many of us over the course of the past year, cooking has become a way to relieve stress and anxiety. Unfortunately, it’s also a major contributor to the high levels of PM2.5 in our homes. Whether you’re sauteeing on a gas range, or pan-frying on an electric stovetop, it’s likely that your mouth-watering meals are launching ultrafine particles of cooked food, fat, or oil into the air. If you are using a gas range, you’re also releasing nitrogen oxides (NOx), including nitrogen oxide (NO) and nitrogen dioxide (NO2), carbon monoxide (CO), and formaldehyde (CH2O or HCHO) into your kitchen.

To some extent, these chemicals and particles are unavoidable when cooking. That’s why it’s incredibly important to have a properly-functioning range hood that vents outside. If you don’t have a range hood, use a wall or ceiling exhaust fan while cooking, or open windows and exterior doors to improve ventilation in your kitchen.

7. Air Fryers

Ahh air fryers – along with microwaving your coffee and getting excited about buying bed sheets, there’s no truer sign of adulthood than owning one. They make even the worst cooks among us feel like professional chefs. But did you know that air fryers are another major source of PM2.5 in your kitchen?

A study from the Wang Jhan-Yang Social Welfare Foundation and the Taiwan Society of Indoor Environmental Air Quality, showed that air fryers can cause levels of PM2.5 to rise by over 1,500 times the normal amount. Even when used with a range hood, air fryers can cause air pollution levels to rise significantly higher than from pan-frying on the stove.

As with just about anything you do in your kitchen, it’s important to only use an air fryer in a well-ventilated area, or near exterior doors and windows to provide air flow.

8. E-cigarettes

The last time you were at a party (which for the majority of us was a very long time ago), you might have noticed people puffing on an e-cigarette. While e-cigs, or vapes, have been touted as a healthier alternative to cigarettes, do they have a significant impact on indoor air pollution?

Despite their popularity, to date there is little available data on their safety for users and secondhand smokers. With that being said, some recent studies have shown that the vapour from e-cigarettes increases levels of PM2.5 in the air. Another study found that they also create volatile organic compounds (VOC), polycyclic aromatic hydrocarbons (PAH), carbonyls, and metals, all of which are inhaled by the user.

While we don’t know for sure what impact all of these emissions may have on our health, you may want to consider grabbing some fresh air the next time you walk into a vapour-filled room.

9. Printers

You may have thought they’d gone the way of the dodo or the wooly mammoth, but printers are back with a vengeance. With many offices closed and more people than ever working from home, printer sales are once again on the rise.

We’re willing to bet you didn’t realize that printers may also be a source of air pollution in your home. As it turns out, printers — especially laser printers — are yet another source of ultrafine particulate matter; one study from the Queensland University of Technology found that many printers emit high levels of PM2.5. Another study from the Atmospheric Pollution Research (APR) journal, found that in an office environment, some printers were a significant source of VOCs.

Though you might not expect it, it’s important to maintain proper ventilation when printing in your home or office.

10. Air Fresheners

The last item on our list is a particularly harmful one. By some estimates, around 75% of American homes use some form of air fresheners. They may make your home smell nice, but they’re also pretty bad for your health. Air fresheners can cause elevated levels of VOCs, such as formaldehyde, acetaldehyde, benzene, toluene, ethyl benzene, and xylenes, in indoor air. These chemicals are all, of course, very bad for you when inhaled at high levels, but it doesn’t stop there.

According to one study “fewer than 10% of air freshener ingredients are typically disclosed to the public.” And “over 20% of the general US population report adverse health effects from air fresheners.” It’s hard to know just how bad these pleasant-smelling fumes are for your health. Even “eco-friendly” air fresheners can be incredibly harmful.

Hidden harms

To better understand what harmful pollutants are floating around your home, you may want to invest in a home air quality monitor.

After reading this list you may be wondering, what doesn’t cause air pollution in my home? While some of these items may surprise you, we all know that knowledge is power. The more you know about what’s harming the air inside your home, the better equipped you can be to protect yourself.


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