Cooking in gas stove releases numerous pollutants like nitrogen dioxide, carbon monoxide, carbon dioxide and PM 2.5 particles. You can overcome this to an extend by using kitchen chimneys and exhaust fan.
Air fresheners and paints release Volatile Organic Compounds like formaldehyde, benzene etc. which contribute to air pollution.
Pet hair and dander can contribute to indoor air pollution, especially for those with allergies. You can overcome this by proper grooming and regular cleaning with HEPA vacuum cleaners and using air purifiers.
Burning candles and incense release Volatile Organic Compounds and PM 2.5 matter which can increase air pollution in your home.
New furniture, carpets and vinyl floorings can release VOCs into the air causing indoor air pollution. You can overcome this by allowing new items to off-gas in a well-ventilated area before bringing them into your living space
While many indoor plants are known for their air purifying qualities, they can produce mold when over-watered. Hence, take care of the watering needs and ensure proper drainage to prevent mold growth.