How to Improve Indoor Air Quality

Why Indoor Air Quality Matters

Indians spend 80–90% of their time indoors, yet indoor air can be 2–5 times more polluted than outdoor air. Poor indoor air quality causes or worsens respiratory conditions, allergies, headaches, and fatigue. Here is a practical guide to making your home’s air cleaner.

Step 1: Control Sources of Pollution

The most effective strategy is eliminating pollution sources rather than filtering them out.

What to eliminate or reduce:

• Smoking indoors (single largest source of indoor PM2.5)
• Burning incense, candles, or mosquito coils
• Using synthetic air fresheners and aerosol sprays
• Gas cooking without exhaust
• New furniture off-gassing (let it air out in a ventilated space before bringing inside)

What to add:

• Houseplants like snake plant, areca palm, and peace lily (modest benefit for VOCs)
• Activated charcoal bags for small spaces
• Low-VOC paints and adhesives for renovations

Step 2: Optimize Ventilation

Proper ventilation dilutes indoor pollutants and reduces CO2 buildup. In polluted cities, this requires timing.

• Ventilate when outdoor AQI is lowest (usually 2–4 PM)
• Use cross-ventilation by opening windows on opposite sides
• Install exhaust fans in kitchens and bathrooms
• Consider a heat recovery ventilator (HRV) with filters for continuous clean ventilation
• Use bathroom exhaust fans during and 20 minutes after showers to reduce mould risk

Step 3: Use a HEPA Air Purifier

A good air purifier with a True HEPA filter can reduce indoor PM2.5 by 80–90% when properly sized for the room.

Selection tips:

• Choose a purifier with CADR (Clean Air Delivery Rate) matching your room size
• For a 150 sq ft bedroom, look for CADR of at least 150 CFM for smoke
• True HEPA (H13 or higher) filters 99.97% of particles down to 0.3 microns
• Avoid “HEPA-type” or “HEPA-like” filters — only True HEPA guarantees performance
• Run the purifier 24/7 during high pollution seasons, not just when you feel discomfort

Step 4: Control Humidity

High humidity encourages mould and dust mites. Low humidity dries out mucous membranes, making you more susceptible to infections.

Target range: 40–60% relative humidity

• Use a dehumidifier during monsoon (humidity often exceeds 80% in coastal cities)
• Use a humidifier during dry winter months (Delhi can drop below 30% in winter)
• Fix leaks promptly to prevent mould growth
• Use exhaust fans in bathrooms

Step 5: Clean Strategically

Conventional cleaning can actually worsen indoor air quality by resuspending dust.

• Wet-mop floors instead of sweeping or dry dusting
• Vacuum with a HEPA-filter vacuum (cheap vacuums leak dust back into the air)
• Wash bedding and curtains weekly in hot water (55°C+ kills dust mites)
• Use microfiber cloths that trap dust rather than pushing it around
• Clean air purifier pre-filters every 2 weeks

Step 6: Seal the Envelope

Prevent outdoor pollution from infiltrating:

• Apply weatherstripping around doors and windows
• Use door sweeps on exterior doors
• Seal gaps around window AC units with foam tape
• Close windows during high-pollution hours (7–10 AM, 6–9 PM in winter)

Key Takeaways

• Source control is the most effective strategy — eliminate indoor burning and smoking
• Ventilate during low-pollution hours (2–4 PM) for clean air exchange
• Use a properly sized True HEPA air purifier in rooms where you spend the most time
• Maintain humidity between 40–60% to control mould and comfort
• Clean with wet methods and HEPA-filter vacuums to avoid resuspending dust