Common Myths About Air Conditioners in Indian Homes

Reality: Most split and window ACs recirculate the air already inside the room. They cool the space and reduce humidity, but they do not bring in fresh air or effectively remove CO₂, VOCs, or fine dust. Running an AC for long hours with closed windows can often lead to a buildup of stale air.

Reality: Standard AC filters are mainly designed to protect the cooling coil from large dust particles. They are not effective at removing fine particulate matter (PM2.5). Standalone air purifiers with HEPA filters handle particulates effectively, while activated carbon filters address gaseous pollutants like VOCs and odours.

Reality: Since most ACs recirculate indoor air, they cannot reduce CO₂. In closed bedrooms or study rooms, CO₂ levels can rise significantly over a few hours, leading to stuffiness and discomfort, even when the temperature feels comfortable.

Reality: ACs can help allergy sufferers. Lower humidity discourages dust mites and mould growth over time. Models with good coil coatings and auto-dry functions actively reduce mould risk inside the unit, which benefits people sensitive to allergens. However, because they recirculate air, standard ACs do not effectively remove airborne allergens like pollen or pet dander from the room.

Reality: BEE star ratings only measure energy efficiency. They have no connection to air filtration, fresh air intake, or how well an AC handles indoor air quality.

Reality: When an AC is switched off, moisture can remain on the coil and drip tray. Without a proper auto-dry function, this can lead to mould and bacteria growth inside the unit. The risk is higher during monsoon, when humidity accelerates mould growth both inside the unit and in the room.

Reality: While keeping windows closed is better on high-pollution days, running an AC continuously for many hours without any fresh air exchange can cause CO₂ buildup. Occasional ventilation (when outdoor air quality is decent) is necessary. Our Ventilation Guide helps you decide when it's better to open windows based on current AQI and indoor CO₂.

Reality: Oversized ACs cool the room quickly but often don't run long enough to dehumidify properly. This can leave the room feeling cold and clammy. Choosing the right tonnage based on room size, sunlight, and occupancy is more important than going for a higher capacity. For the limits of AC-based humidity control, see 8 Dehumidifier Myths Explained.

Reality: Even if the room looks clean, dust, pollen, and microbes accumulate on AC filters over time. Dirty filters reduce cooling efficiency, increase power consumption, and can become a source of indoor pollution when the AC is running. In Delhi or other high-pollution cities, filters may need cleaning every 2–4 weeks during heavy usage months, not just once a season.

Reality: AC performance varies significantly depending on local conditions. In coastal cities, corrosion is a bigger concern. In very hot and dry cities, the AC has to work much harder. In highly polluted cities, indoor air quality becomes a bigger issue when running the AC with closed windows.

Reality: Setting a very low temperature doesn't cool the room meaningfully faster. For fixed-speed ACs, it simply wastes electricity by running at full capacity for longer. For inverter ACs, the unit modulates but still consumes more power without delivering proportional comfort; 24–26°C is the more practical setpoint.

Reality: Many ACs now advertise nanoe, ioniser, or UV features as air purifiers or bacteria killers. However, the real-world effectiveness of these technologies in reducing PM2.5, VOCs, or allergens in typical home conditions is limited and often overstated. Some ionisers can also generate ozone as a by-product, which is itself a respiratory irritant.

Reality: There is no strong scientific evidence that using an air conditioner directly weakens the immune system. However, some related factors can affect how you feel:

• Dry air: ACs reduce humidity, which can dry out the nasal passages and throat. This may make you slightly more prone to irritation or minor infections.
• Temperature shock: Frequently moving between a very cold AC room and hot outdoor conditions can stress the body.
• Poor maintenance: Dirty filters or mould inside the AC can circulate allergens and microbes, which may affect respiratory health.

Moderate and well-maintained use of AC does not reduce immunity. The bigger concerns are usually poor ventilation and lack of maintenance rather than the AC itself.