Delhi's air pollution has reached alarming levels. Hospitals and doctors have reportedly warned about the possible health hazards of the pre-winter smog in the national capital. Meanwhile, the Delhi government has been monitoring the issue and has asked schools to be shut down. There are several complications of air pollution in a city. Air Purifier is one of the technological innovations which act as a saviour in times like these. The pollution levels are usually on the rise right before winter, making it the perfect time for you to buy an air purifier for your home or office. There are several companies, from big brands to new ones, which have their air purifiers in the market. However, there are a few things which need to be kept in mind before you buy the device. Air Purifiers are of various types and sizes and cater to different needs. Firstly, you will have to determine the size of your room, noise levels, electricity consumption, filter replacement price, and certifications. Buyers need to check if their Air Purifier is HEPA labelled. HEPA means high-efficiency particulate air. It is a technology that absorbs particulate matter present in the air of your room. You will have to replace it regularly. You will then have to check the range of the device. The air delivery rate should be over 300 cubic meters so that it covers your room. Preferably do not buy an air purifier with over 100-watt power, in order to save electricity. Here is a list of the top air purifiers options you have: Xiaomi Mi Air Purifier 2: The Xioami device has an aerodynamic system that provides Clean Air Delivery Rate(CADR) of 310m3 It helps users to avoid PM 2.5, dust, and other small particles. The most interesting part is that the device is cylindrically shaped so that it can work in 360 degrees. It also has a smart control system which enables you to use it with a smartphone. The Xiaomi Mi Air Purifier is priced at Rs 8,999, and available on Flipkart and Amazon. Kent Aura: It is a popular air purifier for homes. The device has a HEPA filter which protects against PM 2.5 and SPM. It has a carbon filter that fights bad odour too. The Kent Aura has an inbuilt ionizer that either get the pollutants stick to an electronic plate or on the walls. It has a smaller CADR of 180m3 So, the device is great for smaller rooms. The device has an LED display that shows three colours (blue, pink, and red) based on the air quality levels. It has three-speed levels as well. The Kent Aura is priced at around Rs 11,000 on Flipkart and Amazon. Philips 3000 series: This Air purifier has an extra NanoProtect HEPA and AC filter. The CADR rate of the device is 367m3\/h which makes is good for a very small room. The company claims to have a Vitashield IPS technology capable of getting rid of particles of up to 0.02-micron size that is 100 times smaller than the PM 2.5. It has 4 colour AQI lights, that gives the real-time PM levels in the air. has an allergen mod, that can remove airborne allergens like the H1N1 virus. It is priced around Rs 23,000-Rs 26,000 on Amazon and Flipkart. Honeywell HAC35M1101W Portable: With an intuitive and smart touch interface, this Honeywell air purifier is easy to operate. It has a big filter life of up to 3000 hours. The Clean Air Delivery Rate of the device is of 300 m3\/h and covers around 450 square feets with power consumption of 52 watts. The purifier has a 3D design that gives good air circulation. Interestingly, it also has sleep mode to reduce the noise of the fan. It is priced at Rs 22,990 on Amazon and Flipkart. Sharp FP-FM40E-B: This air purifier also acts as a mosquito catcher. Apart from removing pollutants from the air, it also helps to catch mosquitos. It has a plasma cluster which removes the smell and toxic gases from both air and surface. It also removes pathogens including virus, dust mites, fungi, and more. The area covered by this air purifier is up to 300 square feet and it consumes 33Watts (max) power. The Air Purifier has been certified by 28 global labs for safety. It is priced at Rs 25,999 on Amazon and Flipkart.