The hazardous fine dust particles known as PM2.5 are hitting Bangkok like a silent killer. People are nervous. The N95 respirator masks to filter the minuscule particles, less than 2.5 micrometres in diameter, have quickly sold out. Online communities are flooded with data on how humans -- and animals -- can keep safe.
Amid the current toxic haze scares, apps and websites are fast becoming a major source of reports and forecasts on air quality. These include AirVisual, Air4Thai and website aqicn.org. But too much information can make the head spin. One app will tell you that your neighbourhood is on red alert, another that the air quality is moderate.
Still, technologies created to monitor the air are paramount, according to Asst Prof Prapat Pongkiatkul, head of the Environmental Engineering Department, King Mongkut's University of Technology Thonburi (KMUTT)'s Faculty of Engineering. This is especially the case now that the health-threatening smog is wrecking havoc not just in Bangkok but throughout many provinces.
"Applications and websites for checking air quality are essential, but it is equally important that users understand the data, as well as how the data is processed and reported," he said. Apart from exhaust fumes, PM2.5 mainly comes from burning of all kinds, especially outdoors, with rice straw, incense sticks and joss paper among the chief culprits.
Developed to monitor and report the Air Quality Index or AQI, the official benchmark for communicating to the public how polluted the air is, apps and websites work by collecting and presenting data obtained from air monitors.
"Smartphones don't serve as a sensor or a machine to check the air," said Sarun Sumriddetchkajorn, senior researcher at the Spectroscopic and Sensing Device Research Unit (SSDRU) under the National Science and Technology Development Agency (NSTDA). Some apps have implemented an air monitoring system of their own, while others use and report information they get from the Department of Pollution Control.
AQI doesn't just measure PM2.5; it measures particulate matter (PM2.5 and PM10), ozone, carbon monoxide, nitrogen dioxide and sulphur dioxide. According to the World Air Quality Index, a non-profit project initiated in 2007 to provide the world with air quality information, an AQI value of 0-50 means the air quality is satisfactory, posing little or no risk. A value of 50-100 means moderate, or that the air quality is acceptable but contains some pollutants that can cause health issues among those who are sensitive to air pollution. A number above 100 means the air is unhealthy. If it goes above 300, it could be hazardous to everyone.
WHERE THERE'S SMOKE
- Air pollution kills an estimated 7 million people worldwide every year.
- About 90% of the population living in cities in 2016 was exposed to particulate matter in concentrations exceeding the World Health Organization (WHO) air quality guidelines.
- Nine out of 10 people breathe air that contains high levels of pollutants.
- Some 24% of all stroke deaths are attributed to air pollution, while 43% of lung disease and lung cancer deaths are attributed to air pollution.
- In Thailand in 2017, the provinces with the highest levels of PM2.5 were Saraburi (tambon Na Phra Lan), Bangkok (Intharaphithak Road), Samut Sakhon (Muang district), Ratchaburi (8th Regional Environment Office) and Chiang Mai (tambon Sripoom). In 2016, the five worst affected provinces were Chiang Mai, Khon Kaen, Lampang, Bangkok and Samut Sakhon.
- More than 50% of PM2.5 comes from outdoor burning, 17% from factories, 13% from transportation, 9% from electricity production and 7% from residential and business activities.
Information from the WHO and Greenpeace.
According to Prapat, the concentration of PM2.5 is measured in microgrammes per cubic metre (μg/m³).
"The method used by worldwide agencies as well as the Department of Pollution Control in checking PM2.5 is to weigh the particles," he explained. "A PM2.5 monitor will suck up the air in certain areas and check the weight of the small dust particles per one cubic metre." Although this is the most effective way to measure the PM2.5 concentration, the monitoring system is certainly not affordable to everyone, with prices in the millions.
That perhaps explains why some agencies -- and households -- choose to install sensors to measure the air quality, as they are cheaper. According to Sarun, a sensor works by using laser or a light source to examine the air that flows inside it before reporting as a unit that has been predesignated by users. There are, however, multiple variables that could affect how sensors function and report.
"First, it depends on whether the sensors are certified to international standard," Sarun explained. "Second, it's about where the sensors are installed. If a sensor is located at a spot where the wind is completely stagnant, the result will always be good. Likewise, if a sensor is installed in a place where the wind is flowing all the time, the air quality there will always be reported as clean."
Such differences in measuring approach explain the differing air quality reports on different applications and websites. But the way the data is processed before being reported also contributes to uncorrelated air quality colour codes and numbers which could cause confusion among the public. Take the application AirVisual, for instance. The app is updated constantly, giving almost real-time reports of air quality in certain areas. Air4Thai, by contrast, gives its AQI data based on the 24-hour average. As a result, the AQI values reported by each can be different, even when they are from the same time and location.
"Real-time data is useful for [real-time] monitoring," Prapat said. "But for long-term, the standard [practice] is to look at the average value during the previous 24 hours."
Despite all these technological aspects behind data differences, Sarun is of the opinion that the air quality apps and websites are still a good source of information, especially for frequent travellers.
"Air quality monitoring technologies can be of great assistance to everyday life. They make people more aware and more prepared. But for accuracy, online results should always be compared with what actually happens in those areas," he said.
Prapat echoed this view. While smartphone applications and websites can make life easier, being mindful is actually most vital.
"PM2.5 has long been with us," he said. "I've studied it for a long time and levels are always high. But now people are more aware of it, which is a good sign. But the consequences of PM2.5 among generally healthy people are usually long-term. Short-term exposure to the particles is likely to cause asthma, respiratory conditions and allergies, what we should be worried about is the long-term impact because PM2.5 is carcinogenic. So even if people are checking the app, they should still wear a mask as well."