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ฝุ่น PM 2.5 ใน กทม มาจากไหน?— Tonno (@TonsTweetings) January 10, 2020
การนำเสนอด้วยดาต้าจริง สรุป ปัญหาใหญ่ที่สุดที่ทำให้มีฝุ่น คือการเผาเพื่อการเกษตร https://t.co/PI39dbMMus
Agricultural Burning is a Major Problem !
Farmers in Southeast Asia pick January — March as their burning season. For the north and northeastern provinces in Thailand, these burning activities are large enough to make these provinces among the most polluted places in the world during this time. For Bangkok, one might argue that because the region is heavily industrial rather than agricultural, it may not be affected as much by agricultural burning. But this is not the case.
Because of the tiny size of PM 2.5 particles, they remain suspended in the atmosphere for prolonged periods and can travel over very long distances. From the weather data, the average wind speed is 10 km/hour. The reported PM 2.5 level is a rolling average over 24 hours. A rough estimate is that the current PM 2.5 reading may be from sources as far as 240 km away. The picture below shows the fire map measured by NASA’s satellites, indicative of agricultural burning, on Jan 8, 2018 and on Feb 8, 2018. The yellow circle indicates the area within 240 km of Bangkok. The number of fires on Jan 8, which has an acceptable level of pollution, is much lower than the number of fires on Feb 8, which has an unhealthy level of pollution.
In fact, the fire pattern closely aligns with the PM 2.5 pattern.
