Flu Season Meets School Season: How Smarter Air Quality Keeps Classrooms Healthy

Every fall, classrooms fill with students—and viruses. Discover how smarter air quality strategies like low-resistance filtration, ventilation, and HEPA keep schools healthier, reduce absences, and support better learning outcomes.

Ava Montini

Aug 19, 2025

Written by

Published on

The scene every September

Every September, the school bell rings and hallways come alive again. But as backpacks and lunch boxes make their way back into classrooms, another unwelcome guest tends to sneak in too: flu season.

Teachers know it all too well. The cough that spreads from desk to desk, the hand sanitizer bottles running low by mid-morning, the spike in absenteeism that leaves lesson plans hanging. Parents know it when the inevitable call from the school office comes: “Your child has a fever, please come pick them up.”

It’s a cycle we’ve come to accept as part of the school year. But what if healthier air could help change that story?

Why flu season and school season collide

Respiratory viruses (including influenza) spread more readily indoors, where exhaled particles accumulate. That’s not speculative; CDC/NIOSH is unambiguous that better indoor ventilation reduces occupants’ overall exposure to airborne viruses. CDC

We also know influenza isn’t only about big droplets from a sneeze. People exhale infectious virus in fine aerosols during normal breathing and speaking, which can linger and travel within a room. That was demonstrated in a landmark study that detected infectious influenza virus in exhaled breath from symptomatic adults, no cough required. PNAS Nature

The drier, colder air from the fall and winter cause low humidity, helping influenza survive and transmit more efficiently. Put simply: when we bring students back into dry, tightly sealed buildings, small airborne particles build up and stay infectious longer. That’s the fixable part.

Think of clean classroom air as a budget with three line items:

Dilute what’s in the room (ventilation/outdoor air)
Remove what’s in the room (filtration/air cleaning)
Disable what’s in the room (UVGI where appropriate)

The key is using them together, sized to the space, and tuned to the school day.

What the standards now say and why it matters

Before the pandemic, most schools designed ventilation systems mainly for comfort—things like controlling odours or keeping CO₂ levels down—not for stopping the spread of illness.

That changed with ASHRAE’s new Standard 241, which focuses specifically on infection control. ASHRAE’s Standard 241: Control of Infectious Aerosols changes the target by introducing Equivalent Clean Airflow (ECA)—a flexible, additive way to hit a per-person clean air goal using any combination of ventilation, filtration, and proven air cleaning. That means a classroom can meet its target by mixing outdoor air with high-efficiency filters, HEPA units, and/or UVGI, rather than relying on outdoor air alone. ASHRAE+1

In parallel, CDC/NIOSH and EPA emphasize practical steps for schools: keep systems maintained, upgrade to MERV-13 or better where equipment allows, and supplement with portable HEPA when central systems can’t carry the whole load. CDC+1 Environmental Protection Agency

The evidence that this keeps kids in class

In a study of 162 California elementary school classrooms, illness-related absences dropped by 1.6% for every extra 1 l/s‑person of ventilation. Increasing ventilation to meet the state standard (7.1 l/s‑person) from the average (4 l/s‑person) could reduce absences by 3.4%, gain $33 million annually in attendance-based funding, while costing just $4 million more in energy.
A study across Washington and Idaho found that a 1,000 ppm increase in indoor CO₂ correlated with a 0.5–0.9% drop in average daily attendance, translating into a 10–20% rise in student absences.
In controlled environments, each 500 ppm rise in CO₂ resulted in 1.4–1.8% slower response times, along with a 2.1–2.4% lower throughput on cognitive tasks.
Harvard’s COGfx study revealed that building occupants in green-certified, well-ventilated environments scored, on average, 101% higher in cognitive tests than those in conventional buildings.

“Will MERV-13 break my units?” (The energy/airflow reality)

The honest answer: it depends on the filter you pick and your fan capacity. Research on rooftop units shows that moving from MERV-8 to MERV-13/14 can raise cooling-mode energy use by a few percent if the filter adds a lot of resistance, or it can reduce airflow if the fan can’t keep up. That’s why filter selection matters as much as efficiency.

Not all MERV-13 filters are created equal. Traditional pleated designs often create a higher pressure drop, forcing HVAC systems to work harder and sometimes leading to performance issues. But newer filtration technologies (explicitly engineered for low resistance at high efficiency, like Blade Air's Pro Filter,) are changing that equation. By combining advanced media with optimized form factors, these filters deliver MERV-13 (and higher) performance without the heavy airflow penalty.

California’s Title 24 research reinforces this point: Many modern low-pressure MERV-13 options can maintain pressure drops under 0.20 in. w.c., keeping systems within safe operating ranges. That means schools can improve air quality, meet public health guidance, and stay compliant without sacrificing system efficiency or longevity.

When you factor in the bigger picture—fewer student absences, better cognitive performance, and improved overall school operations—the ROI clearly tilts toward upgrading. Healthier air doesn’t just protect occupants; it protects the bottom line.

How this translates into a classroom target (the ECA idea)

ASHRAE 241’s Equivalent Clean Airflow lets you add up all the ways you’re cleaning air—outdoor air, central filtration, HEPA, UVGI—until you reach the per-occupant target for your space type. It’s flexible, measurable, and avoids unrealistic demands for 100% outdoor air in cold snaps. ASHRAE

A practical approach:

Estimate your current outdoor air (from design or testing).
Add the “clean air” from MERV-13 upgrades (using published efficiencies) and from each HEPA unit’s clean air delivery rate.
If the sum doesn’t meet the ECA target, add another portable unit or rethink your filtration strategy. ASHRAE

What about measurement and transparency?

CO₂ for ventilation

Track a few representative rooms across grade levels and building wings. Persistently high readings during class point to areas needing a fix (dampers, schedules, or supplemental air cleaning). Health Canada’s 1000 ppm residential benchmark is a useful anchor for conversations with families and staff. Canada.ca

PM₂.₅ for smoke days

A couple of low-drift sensors at kid-height in hallways or problem rooms can confirm your filtration strategy keeps indoor levels below outdoors during wildfire events. Health Canada and EPA both recommend this principle. Canada.ca

Bottom line

Flu season doesn’t have to mean higher absence rates and strained HVAC systems. The most effective path is a consistent program: keep ventilation tuned, use filters that balance efficiency with low resistance, and supplement with portable HEPA or UVGI where it makes sense.

How to Eliminate Office Odours – Your Guide to A Clean Office

Jennifer Crowley
Aug 2, 2023
3 min read

Updated: Jul 19, 2024

Modern white office space with a wall of floor to ceiling windows, black doors, shelving and chairs — Eliminating office odours is crucial for maintaining a pleasant and productive work environment.

A pleasant and fresh-smelling office environment is crucial for employee morale and productivity. Unpleasant office odours can create discomfort and distractions, negatively impacting the overall work atmosphere.

In this blog post, we will explore effective solutions for eliminating various office odours that commonly arise. By implementing these strategies, you can create a more pleasant and inviting workspace for everyone.

Bathroom Odours

Bathrooms are notorious for harbouring unpleasant smells. Here are some tips to combat bathroom odours in the office:

Small washroom toilet and sink with female arm spraying an air freshener spray — Proper ventilation is essential for preventing odour accumulation.

Regular Cleaning: Ensure that the bathroom is cleaned thoroughly and frequently. Pay extra attention to toilets, sinks, floors, and any other surfaces prone to odour buildup.
Adequate Ventilation: Proper ventilation is essential for preventing odour accumulation. Install air fresheners or use natural alternatives like essential oil diffusers or fresh plants.
Odour Neutralizers: Odour neutralizers, such as activated charcoal or baking soda, are essential items to keep in your bathroom. These substances work effectively to absorb and eliminate unpleasant smells, ensuring a consistently fresh and inviting atmosphere in your restroom.

Breakroom Odours

The breakroom is a common area where food odours can linger. Follow these steps to tackle breakroom odours effectively:

Communal office space with two employees eating pizza, drinking water and watching a movie — Encourage employees to clean up after themselves promptly.

Encourage Cleanliness: Encourage employees to clean up after themselves promptly. Clear policies about cleaning up spills, refrigerating food properly, and disposing of waste can help prevent odour issues.
Proper Ventilation: Ensure the breakroom has adequate ventilation to dissipate food odours. Open windows or install ventilation fans if necessary.
Regular Cleaning and Maintenance: Establish a routine cleaning schedule for the breakroom, including wiping down surfaces, emptying garbage bins, and cleaning the microwave or refrigerator.

Other sources of breakroom odours can derive from:

Sink odours: Sinks can develop unpleasant odours due to food particles and bacterial growth. Here’s how to address sink odours effectively.

Fridge odours: Unpleasant smells can quickly develop in refrigerators due to spoiled or forgotten food items. Follow these steps to keep your office fridge smelling fresh.

Eliminate Office Carpet Upholstery Odours

Carpets and upholstery can absorb various odours over time. Consider the following tips for freshening up your office’s soft surfaces:

Beige carpet with a black upright vacuum on top with two female feet standing on the edge of the carpet — Use a vacuum cleaner with a HEPA filter for the best results.

Regular Vacuuming: Vacuum carpets and upholstery frequently to remove dust, dirt, and odour-causing particles. Use a vacuum cleaner with a HEPA filter for the best results.
Spot Cleaning: Attend to spills or stains on carpets and upholstery promptly. Blot the area with a clean cloth and use a mild detergent or specialized cleaners designed for specific fabrics.
Professional Cleaning: Schedule professional deep cleaning for carpets and upholstery at regular intervals to remove deep-seated odours and rejuvenate the fibres. Professional cleaning methods, such as steam or dry cleaning, can effectively eliminate odours and refresh the appearance of the carpet and upholstery.

Trash Can Odours

Trash cans can emit unpleasant odours, especially when filled with food waste or other organic materials. Follow these steps to keep trash can odours at bay:

Stainless steel garbage can with the lid open awaiting a white napkin to be dropped inside with a white subway tile backdrop — Regularly clean and disinfect trash cans to eliminate lingering odours.

Regular Emptying: Empty trash cans regularly to prevent the buildup of odorous waste. Establish a schedule for emptying and ensure that employees adhere to it.
Proper Bag Sealing: Double-bagging trash or using heavy-duty garbage bags can help contain odours. Tie the bags securely to prevent any leaks or spills.
Odour Absorbers: Place odour-absorbing materials at the bottom of the trash can, such as baking soda, kitty litter, or activated charcoal. These substances can help neutralize odours effectively.
Cleaning and Disinfecting: Regularly clean and disinfect trash cans to eliminate lingering odours. Use a mixture of water and vinegar or mild detergent to scrub the inside and outside of the trash cans.

Eliminating office odours is crucial for maintaining a pleasant and productive work environment. By following the tips and strategies outlined in this blog post, you can tackle common sources of odours such as bathrooms, break rooms, sinks, fridges, carpets, upholstery, and trash cans. Regular cleaning, proper ventilation, and the use of natural odour neutralizers are crucial to keeping your office smelling fresh and inviting. Implement these practices consistently, and you’ll create a more comfortable workspace that promotes productivity and well-being for everyone.

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