For the fifth day in a row, air quality index (AQI) in the city remained in the `very poor' category as it again beat the national capital in pollution levels. According to real time data monitored by System for Air Quality Weather Forecasting and Research (SAFAR), the recorded AQI on Tuesday morning was 307 which improved marginally to 306 during the day . On Monday morning, the AQI was 308 which dipped to 304 by the evening. On the other hand, high wind speeds and temperatures which dispersed pollutants kept New Delhi's AQI at 215 and 219 on Tuesday morning and evening respectively. AQI uses the 24-hour averages of pollutants, including sulphur dioxide, nitrogen oxide, carbon monoxi de, ozone (O3) and particulate matter. An AQI between 301 and 400 is considered very poor and people with heart or lung diseases, older adults and children should avoid prolonged or heavy exertion while everyone else should reduce the same. The city's AQI has taken a hit since the fire started at the Deonar dumping ground due to an increase in the PM 10 (particulate matter which measures less than 10 microns) emissions which are a direct effect of open fires and burning of bio-mass. The AQI of 341 on January 29 was the worst since June 2015 when SAFAR started monitoring the city's air quality. According to SAFAR's predicted AQI of 305 for Mumbai on Wednesday , the pollution is expected to remain in the `very poor' category. “Since the fire is almost doused, the air quality will inch towards getting better but the pollutants are getting dispersed very slowly as the wind speed is only moderate.The low temperatures and high humi dity are also keeping the particulate matter close to the Earth's surface,“ said Gufran Beig, project director, SAFAR. Among the 10 locations where SAFAR monitors AQI, it was in the very poor category in most of the suburbs.Chembur, which is very close to the site of the fire, recorded an AQI of 369, followed by Mazgaon at 329 and Andheri at 322. Navi Mumbai too recorded an AQI of 332. The AQI was in the moderate (below 200) category in Worli, Colaba and Malad. As per SAFAR's forecast, researchers said that the air quality is likely to improve only by the end of the week.“Around Friday , AQI levels are likely to go from the `very poor' to the `poor' levels. Since temperatures are also expected to increase next week,“ said Beig.