Air quality in Mumbai on Friday was worse than that during Diwali. The Air Quality Index (AQI) – a pollution measurement tool – in the morning was 315 which falls under the ‘very poor’ category. On November 12, the day after Diwali, the AQI was 313. Pollution levels are likely to remain at alarming levels over the weekend with a predicted AQI of 312 for Saturday. An AQI of more than 300 falls in the very poor category.

A health advisory warning from The System of Air Quality and Weather Forecasting and Research (SAFAR), which measures and forecasts air quality in Mumbai, said: “People are advised to avoid outdoor activity, especially children and senior citizens. It is advisable to use pollution masks.”

SAFAR said that meteorological forecasts have indicated that pollution levels are expected to drop from Monday onwards. “The whole country is reeling under poor to very poor pollution levels due to current weather conditions. Cities like Mumbai are experiencing extremely poor air quality due to high levels of humidity combined with calm winds holding pollutant particles closer to the surface. However, we expect winds to pick up from Monday onwards that will improve Mumbai’s air quality,” said GufranBeig, project director, SAFAR. “We calculated the average AQI of 315 on the basis of the magnitude of suspended pollutant particles overnight and on Friday morning. However, the AQI dropped through the day to 307 as wind patterns dispersed some of the pollutant particles by the evening on Friday.” he said.

Humidity levels in south Mumbai and the suburbs were 77% and 85% respectively.

On Friday, eight out of nine locations in the city where SAFAR measures pollution levels recorded either ‘very poor’ or ‘poor’ pollution levels. Chembur that has been recording good air quality for the last five days also recorded an AQI of 194 falling under the ‘moderate’ category. Pollution was highest in Malad where AQI was 359; it was 343 at Andheri.

Concentration of PM2.5 and PM10 - particulate matter with a diameter of 2.5 and 10 micrometres that can penetrate deep into the respiratory system – was high. As against the safety limit of 60 microgrammes per cubic metre (µg/m3), Mumbai’s air had a PM2.5 concentration at 131µg/m3. PM10 levels were ‘moderate’ at178.4µg/m3, against safety standards of 100µg/m3.

Scientists said that while the government has been taking steps at the macro-level to control pollution, citizens need to safeguard themselves by protecting indoor air quality. “When moisture levels increase, bio-aerosols –suspended airborne particles, including dust, bacteria, fungi or virus that settle - rises. They are responsible for a number of lung-related diseases,” said Padma Rao, senior principal scientist and head, air pollution control division, National Environment Engineering Research Institute (NEERI), Nagpur.

Rao added that immediate measures were needed to purify indoor air quality. “Increasing the green cover around houses, keeping doors and windows closed once the house is cleaned and switching off electrical equipment to conserve electricity,” she said.