Why Does Your Child Cough or Get Sick Often, Even When Your Home Looks Clean?

date_range 22 April 2026

Does your child often cough, have a runny nose, or get sick frequently—even though your home is clean and regularly maintained? Many parents face this situation: everything seems to be done right, yet the symptoms keep coming back.

One of the most common causes can be the air your child breathes every day.

Even in well-kept homes, indoor air may contain:

🌿 pollen, 💨 particulate matter (PM10, PM2.5), 🧪 VOCs and odours

👉 The real question is not “if they’re present”, but how much of them reach your breathing zone.

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Komfovent Systemair Zehnder Vent-Axia

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Why are children more sensitive to indoor air quality?

Children are more sensitive to air quality because their respiratory system is still developing. Even low levels of indoor air pollution can quickly lead to coughing, a runny nose, or general discomfort.

👶 Developing respiratory system

💨 Higher air intake relative to body weight

🏠 Spend more time indoors

👉 The same air can affect a child more strongly than an adult.

What really affects indoor air quality?

Indoor air quality depends not only on outdoor pollution, but also on how air is filtered and circulated within your ventilation system. Incorrect or clogged filters can significantly reduce overall system performance.

Air quality depends on two key factors:

🌍 The quality of incoming outdoor air

⚙️ How efficiently it is filtered and circulated

👉 If one fails – the whole system becomes ineffective.

Common issues (the real causes)

Symptoms like coughing, sneezing, or eye irritation are often not random. They are commonly linked to ongoing exposure to airborne pollutants that enter from outside or accumulate indoors.

🌿 1. Pollen (allergens)

Enters indoor spaces through ventilation. Without proper filtration, it is not effectively captured.

👉 Can trigger allergic reactions

In children, this often appears as:
• runny nose without a clear cause
• sneezing
• eye irritation

💨 2. PM10 particles (irritation)

Originating from dust, traffic, and the environment. These irritate the airways.

In children, this may cause:
• dry cough
• sensitive mucous membranes
• breathing discomfort

🧪 3. PM2.5 and fine particles

Penetrate deeper into the respiratory system and have long-term effects.

For sensitive children, this may lead to:
• more frequent airway irritation
• increased environmental sensitivity

🏠 4. Indoor air circulation issues

Clogged filters reduce airflow, increasing pollutant concentration indoors.

This is often noticed as:
• “heavy” or stale indoor air
• poorer sleep quality
• morning fatigue

What do filters actually do?

Properly selected filters help reduce not only visible dust, but also fine particles, allergens, and odours. This is essential when you want not just ventilation, but control over the air entering your home.

Filters act as a barrier between outdoor and indoor air.

🟫 G4 – coarse particles

🟪 M5 – medium particles

🟩 F7 – fine particles & allergens

⚫ Activated carbon – odours & VOCs

👉 Goal: reduce the amount of pollutants entering your home.

When do filters stop working effectively?

⏳ Not replaced for 4–6 months

📉 Reduced airflow

👃 Noticeable odours

🌫️ Heavy, stale indoor air

👉 It’s not only about filtering outdoor pollution, but also removing pollutants that build up indoors. In many cases, indoor air can be several times more polluted than outside. Clogged or overdue filters reduce both pollutant removal and fresh air supply.

🔧 Which filter should you choose for your situation?

🌿 If allergies are an issue

M5 – F7 class

👉 F7 captures allergens more effectively

Find filters for allergies →

🔥 If you notice smoke odours

heating, traffic, wildfires

Filters with activated carbon

👉 reduce odours and chemical pollutants

View carbon filters →

🏭 If you live in a polluted area

traffic, industry, urban pollution

Min. F7 (Eurovent recommendation)

👉 important for reducing PM2.5

View F7 filters →

🌱 If outdoor air quality is good

G4 – M5

👉 basic filtration level

View standard filters →

👉 Choose a filter that matches your ventilation unit

• correct filter class
• stable airflow
• full compatibility

View all filters →

⚙️ What else should you consider when choosing a filter?

Filter class is not the only factor.

🔒 Airtight fit
The filter must be properly sealed
Even small gaps allow air to bypass the filter

👉 even an F7 filter won’t work if it’s not airtight

🧵 Filter media
PFAS-free
The filter material should not release harmful substances.

📊 Certification
Tested according to ISO standards
Ensures actual filtration performance

🧼 Hygiene
Resistant to microorganisms
Important for long-term use (VDI standard)

👉 Choose a reliable filter for your ventilation unit

View filters →

What can you realistically improve?

• lower particle concentration
• more stable airflow
• reduced irritation

👉 this is not treatment, but a controllable factor

FAQ

🌿 Why does my child often cough at home even when it looks clean?

Even in clean homes, indoor air can contain pollen, fine particles, odours, and other pollutants. When these enter the breathing zone, they can irritate the respiratory system.

😴 Can indoor air quality affect a child’s sleep?

Yes. Heavy or stale air, odours, and airborne irritants can lead to poorer sleep quality and increased breathing discomfort during the night.

💨 Which filters are best for children with allergies?

M5 to F7 class filters are most commonly used. For higher sensitivity, F7 filters are more effective at capturing fine particles and allergens.

⏳ How often should filters be replaced?

Typically every 4–6 months. In environments with higher pollution, smoke, or dust, more frequent replacement is recommended.

⚙️ Is ventilation alone enough for good air quality?

Not always. If polluted air enters the home, it’s important not only to ventilate but also to properly filter the incoming air.

🔥 Do indoor odours indicate poor air quality?

Yes. Odours often indicate the presence of VOCs or combustion-related particles. In such cases, activated carbon filters can help reduce them.

Sources

• WHO – air pollution and health
• EPA – indoor air quality
• CDC – effects of smoke exposure
• PM2.5 studies (asthma, respiratory system)

Categories: Indoor air quality

Manufacturer of MVHR	Zehnder
Manufacturer	CleanFilter
Air handling unit	ComfoAir Q 600 ComfoAir Q 450 ComfoAir Q 350
Filter dimensions	500x159x22
Class EN779	F7+G4
Class ISO16890	ePM1 65%
Protection level	High: fine particles, dust, pollen, mold spores, combustion particles, smog particles, insecticide dust.
Quantity of filters	2
Advantages	Better protection from fine particles: ePM1 65% filtration (many original filters are typically ~ePM1 50–55%). Cleaner indoor air: mechanical filtration helps capture combustion (soot) and traffic-related particles without relying only on electrostatic charge. Easier airflow: up to 3× lower initial resistance compared to the previous material (internal lab tests). Proven performance: tested according to ISO 16890, made in the EU.
Manufacturer product number	400100118 400502015 400502013
Remarks	⚠️ Remarks: ComfoAir ≠ ComfoAir Q. Different dimensions, not interchangeable. Check your ventilation unit model/version before ordering.

Manufacturer of MVHR	Blauberg
Manufacturer	CleanFilter
Air handling unit	KOMFORT EC D5 180 KOMFORT D5 180
Filter dimensions	214x186x48
Class EN779	F7
Class ISO16890	ePM1 70%
Protection level	High: fine particles, dust, pollen, mold spores, combustion particles, smog particles, insecticide dust.
Quantity of filters	1
Advantages	Maximum protection – ePM1 70% removes up to 40% more smog, pollen and fine dust than standard filters (50–60%). Made in the EU – reliable quality and strict safety standards German filtration material – hygienic (VDI 6022) and PFAS-free, for cleaner and safer air ISO 16890 tested – performance verified by an accredited laboratory in Germany
Remarks	ℹ️ This MVHR unit has 3 filter slots: Supply air: G4 (mandatory) + optional F7/F8 (for pollen, smog, fine particles). Extract air: G4 (mandatory) 👉 The two G4 filters are always required. The F7/F8 filter is optional for extra protection. ℹ️ This is a supply air filter. For extract air filtration, please order a separate G4/M5 filter (available in our shop). ℹ️ Recommended with 2×G4 filters. The G4 before the F7/F8 captures coarse particles and extends F7/F8 filter life up to 2×.

Manufacturer of MVHR	Komfovent
Manufacturer	CleanFilter
Air handling unit	Domekt R 400 V C6M
Filter dimensions	428x231x46
Class EN779	F7+M5
Class ISO16890	ePM1 70%
Protection level	High: fine particles, dust, pollen, mold spores, combustion particles, smog particles, insecticide dust.
Quantity of filters	2
Advantages	Maximum protection – ePM1 70% removes up to 40% more smog, pollen and fine dust than standard filters (50–60%). Made in the EU – reliable quality and strict safety standards German filtration material – hygienic (VDI 6022) and PFAS-free, for cleaner and safer air ISO 16890 tested – performance verified by an accredited laboratory in Germany
Manufacturer product number	1054682
Remarks	⚠️ Suitable only for C6M models (from 10/2020). Please check model or filter dimensions before ordering. 🌟 High-quality replacement filter: made from certified materials (Germany, SANDLER AG) with tested performance. Provides reliable air filtration and optimal service life.

Manufacturer of MVHR	Systemair
Manufacturer	CleanFilter
Air handling unit	SAVE VTR 150 (PF)
Filter dimensions	302x137x130 307x131x130
Class EN779	F7+M5
Class ISO16890	ePM1 70%
Protection level	High: fine particles, dust, pollen, mold spores, combustion particles, smog particles, insecticide dust.
Quantity of filters	2
Advantages	Maximum protection – ePM1 70% removes up to 40% more smog, pollen and fine dust than standard filters (50–60%). Made in the EU – reliable quality and strict safety standards German filtration material – hygienic (VDI 6022) and PFAS-free, for cleaner and safer air ISO 16890 tested – performance verified by an accredited laboratory in Germany
Manufacturer product number	145777 211121 212120
Remarks	ℹ️ Dimensions are provided according to the Systemair standard (with gasket). Actual filter dimensions without the gasket may differ slightly. The filter is matched to your unit model.

Manufacturer of MVHR	Paul
Manufacturer	CleanFilter
Air handling unit	Paul Novus 300 Paul Novus 450
Filter dimensions	180x475x50
Class EN779	F7/AC
Class ISO16890	ePM2.5 60%
Protection level	Particles and odors: fine particles, dust, pollen, mold spores, combustion particles, volatile particles, NOx, O3 gases.
Quantity of filters	1
Advantages	Made in the EU – reliable quality and strict safety standards German filtration material – hygienic (VDI 6022) and PFAS-free, for cleaner and safer air ISO 16890 tested – performance verified by an accredited laboratory in Germany Absorbs volatile particles (odors) and harmful gases as NOx, O3, etc.

Why Does Your Child Cough or Get Sick Often, Even When Your Home Looks Clean?