Persistent PM2.5 increasing lung cancer risk, experts warn at conference

It has also been found that during periods when there is high presence of particulate matter smaller than 2.5 microns in diameter (PM2.5) in the air, there is a 30% increase in feelings of depression among the population.

This highlights the need to tighten the particulate matter standards, which would potentially safeguard up to 67% of the population from cancer risks, experts said at the first national-level conference on PM2.5 air pollution. The two-day conference on “Clean Air: Shared Responsibilities of the Government, Private Sector, and Society” was held on December 3-4 in Chiang Mai.

The conference deliberated on the readiness of the Thai healthcare system in dealing with the fallout of air pollution, especially high lung cancer mortality in the northern regions.

Dr Patthrarawalai Sirinara, from Chulalongkorn University's Department of Preventive and Social Medicine, said that lung cancer mortality rate in the upper northern region was found to be the highest at 34.08 per 100,000 population in 2017, followed by Bangkok with 32.88. Over the past 20 years — 1997 to 2017 — a continuously increasing trend has been observed. The provinces with the highest mortality rates were:

Lampang: 43.11 (per 100,000 population), which is 1.5 times higher than the regional average

Lamphun: 40.93

Phayao: 38.03

Chiang Mai: 35.27

Concerns regarding lung cancer due to PM2.5 were not solely about the particles, but also included the chemicals within PM2.5, the experts said. Therefore, a study was conducted on the health impacts of cancer-causing agents in PM2.5 among residents in Bangkok.

Initially, Thailand set the PM2.5 standard at 50 micrograms per cubic metre (mcg/m3). However, in June this year, it was revised down to 37.5mcg/m3. Analysis revealed that Bangkok experiences around six months of elevated PM2.5 levels per year.

Regarding the assessment of excess lifetime cancer risk from PM2.5, it was noted that within the same province, the risk levels for developing cancer due to PM2.5 varied across different areas. In industrial-heavy areas like Bangna district in Bangkok, the cancer risk for adults aged 18-70 was 1 in 43,478 people, while in residential areas like Ari (north of Bangkok) it was 1 in 72,992 people. For the age group of 0-6 years in Bangna, the risk was 1 in 86,206 people, whereas in Ari it was 1 in 147,058 people. This indicates a higher cancer risk for those under 6 years old compared to older children and adolescents.

Using a model to estimate the potential reduction in cancer risk from PM2.5 if the standards were lowered to 25mcg/m3 (as per WHO) revealed a potential risk reduction of 27.22%. If the standards were further tightened to 15mcg/m3 (as per new WHO guidelines), it could potentially save up to 67% of the population from PM2.5-related cancer, Dr Patthrarawalai said.

During periods of high air pollution, there's an increase in depressive tendencies. According to Asst Prof Dr Worawan Sirichana from the Respiratory and Critical Care Unit, Faculty of Medicine, Chulalongkorn University, air pollution poses a silent threat, increasing the risk of various diseases and fatalities.

This is directly related to exposure to PM2.5 particles, affecting organs such as the lungs, bronchi, blood vessels, leading to heart, brain, and other organ issues. Prominent side-effects observed include respiratory issues, cardiovascular diseases, and cancer.

Global health data reveals that annually 7 million people die prematurely due to air pollution in both ambient and household settings. The causes include 21% from pneumonia, 20% from stroke, 34% from heart and vascular diseases, 19% from chronic obstructive pulmonary disease and 7% from lung cancer.