Metro Manila air quality improves during quarantine

Metro Manila (CNN Philippines, March 25) – Metro Manila's air quality has improved during the enhanced community quarantine to contain the spread of COVID-19, the Department of Environment and Natural Resources said Wednesday.

The government's restriction on movement and business operations in the entire Luzon entered its 9th day on Wednesday. Under the quarantine, only workers in critical industries like healthcare, food preparation, banks, groceries, and media are allowed to report to work while the rest were told to stay at home. Malls, offices and all forms of public transportation were also shut.

On March 22, the 24-hour average level for particulate matter or PM10 in Las Pinas dropped to 31.67 micrograms per normal cubic meter of air (ug/Ncm) while in Marikina it fell to 27.21 ug/Ncm. The acceptable threshold level in PM10 is 150 ug/Ncm.

PM10 are “inhalable particles with diameters that are generally 10 micrometers and smaller.”

Also on March 22, the PM2.5 levels posted low marks of 10.78 ug/Ncm in Muntinlupa and 14.29 ug/Ncm in Paranaque. The acceptable limit in PM 2.5 is 50 ug/Ncm per 24 hours and 35 ug/Ncm per an average of one year.

As of March 20, the air quality index in some of Metro Manila cities tallied low marks such as Makati (2 PM10), Marikina (18 PM10), Paranaque (6 PM10), Pasig (45 PM10), San Juan (23 PM10), Taguig (38 PM10), and Quezon City (13 PM10).

All the scores meant that “air pollution poses little or no risk” in these areas.

Low PM10 emissions in Metro Manila were attributed to the reduced usage of crushing and grinding machines and low exposure of dust from cemented and dirt roads.

The low PM2.5 emissions in the region, one the other hand, were due to low emissions from motor vehicles, fossil fuel power plants, and wood burnings among others.

The Luzon-wide enhanced community quarantine will last until April 13.