IT WAS a rainy New Year's day last 2019. The rare occurrence was caused by a low pressure area and the northeast monsoon or hanging amihan. Because of the rain, there was a reduction in fireworks and outdoor activities. The Department of Health (DOH) said that firecracker-related injuries nationwide were 80 percent lower than the five-year average.

The reduction in firecrackers and fireworks also resulted in less air pollution in the first day of 2019. The monitoring done by the Environmental Pollution Studies Laboratory (EPSL) of the University of the Philippines (UP) showed that air pollution levels in Metro Manila during New Year's eve was still poor but was at an all-time low. The rains also washed away the tiny particles emitted by pyrotechnics.

As expected, the first day of 2020 was filled with polluted air. In Metro Manila, where there are air quality monitoring stations, results showed that pollution between 11 p.m. of December 31, 2019 and 2 a.m. of January 1, 2020 reached levels that are hazardous to human health, according to Department of Environment and Natural Resources (DENR) Undersecretary Benny Antiporda.

Results obtained from a monitoring station in Mandaluyong City showed that particulate matter 10 (PM10), with diameter of 10 micrometers or less, was measured at 497 micrograms per normal cubic meter (ug/NCM) in Mandaluyong, followed by Taguig with 355 ug/NCM and North Caloocan with 332 ug/NCM. For the monitoring of fine dust particles with diameter of 2.5 micrometers or less (PM 2.5), stations in Pateros Station recorded 399 ug/NCM, Las Piñas Station has 376 ug/NCM and Pasig Station yielded 367 ug/NCM.

In Central Luzon, the Meycauayan, Bulacan air quality monitoring station of the regional office of the Environmental Management Bureau (EMB) showed that the concentration of PM10 peaked at 80.69 ug/NCM between 12 a.m. to 1 a.m. of New Year's day. It is much lower than that of Metro Manila. The Air Quality Index (AQI) was at 25 which is still within the "moderate" range.

According to the World health Organization, particulate matter (PM) is a common proxy indicator for air pollution. It affects more people than any other pollutant. The major components of PM are sulfate, nitrates, ammonia, sodium chloride, black carbon, mineral dust and water. It consists of a complex mixture of solid and liquid particles of organic and inorganic substances suspended in the air.

Particles with a diameter of 10 microns or less, (≤ PM10) can penetrate and lodge deep inside the lungs. Even more health-damaging particles are those with a diameter of 2.5 microns or less, (≤ PM2.5). PM2.5 can penetrate the lung barrier and enter the blood system. Chronic exposure to particles contributes to the risk of developing cardiovascular and respiratory diseases, as well as of lung cancer.

The WHO limits for PM fine particulate matter (PM2.5) is 10 μg/m3 annual mean and 25 μg/m3 24-hour mean. For coarse particulate matter (PM10), the standards is 20 μg/m3 annual mean and 50 μg/m3 24-hour mean.