NEW DELHI: People are scratching their eyes, clutching their aching heads and having difficulties with breathing. With civic authorities paralysed and unable to do anything to prevent a dome of toxic air covering the city, and the weather playing spoilsport in washing or carrying away the pollutants, technology seems like the last resort. TOI looks at the functioning of devices like air purifiers and tries to understand why even this costly assistive appliance may not fully meet people’s needs.
Track the pollution level in your city
While hesitantly calling it a temporary solution, experts caution against the prolonged use of air purifiers, which require them to be used in enclosed spaces, pointing out how carbon dioxide levels could make indoor environments dangerous for health. According to Priyanka Kulshreshtha, co-founder, Society for Indoor Environment, while the capacity of an air purifier matters as some devices cater to smaller areas while others cover more, there is constant leakage of air through locked doors or windows. She said if a room is well sealed, the air purifier will manage the PM2.5 by trapping it in pre-filters, HEPA filters and activated carbon filters, but it does not address the CO2 problem.
Kulshreshtha said CO2 concentration is around 400 parts per million (ppm) outdoors and 1,100 indoors. However, while sleeping in a closed room, the gas can reach concentrations of 2000-2500 ppm, which can prove harmful. “We are emitters of CO2. In a sleep lasting eight hours, our exhalation can raise CO2 concentration to up to 2500 ppm, irrespective of whether an air purifier is installed or not,” she said. She also cautioned against everyone using air purifiers. “For sick people, the device is recommended,” Kulshreshtha said, “but if a child gets accustomed to an air purifier and then goes outdoors, either to go to school or to play, the exposure to unfiltered air would be extreme.” She suggested ensuring ventilation in a room, but not opening windows early morning or late evening, or wearing an N95 mask.
According to Shambhavi Shukla of the Centre for Science and Environment, purifiers aren’t efficient because as soon as a locked room is opened, the pollution shoots up. “Air filters function when you close a room completely. But one cannot be inside a closed room for a whole day. Besides, even a slight crack or short opening of the door would send the impure air in the room shooting up again,” said Shukla. However, given the dire air situation at the moment, experts suggested the use of ventilators while ventilating the room from time to time. This would make their use less harmful.
Sunil Dahiya, founder and lead analyst, Envirocatalyst, said in any case only a fraction of Indian population could afford air purifiers and most Indian homes weren’t designed for such devices. “A majority of people live in houses that aren’t sealed or isolated from the outside, which means outdoor polluted air will keep entering, reducing the usefulness of air purifiers. And staying indoors can take a toll on mental health,” he said. “Purifiers can’t shield us from high pollution levels. They only give us temporary relief, that too for a very limited population who can afford the device or have houses that are sealed properly,” said Dahiya.
#Air #Purifiers #Polluted #Cities #Temporary #Relief #Health #Hazard #Delhi #News #Times #India
