The status of PM₂.₅ and Its Impact on Public Health in Vietnam
Air pollution is one of the major environmental challenges facing nations worldwide. According to the World Health Organization (WHO), there are around 7 million premature deaths due to exposure to polluted air around the world each year. The 2022 Environmental Performance Index – EPI, showed that exposure to air pollution in Vietnam ranked 130 out of 180 nations.
The “Status of PM₂.₅ and Its Impact on Public Health in Vietnam 2021” report was made by the research team from the University of Engineering and Technology, Vietnam National University, Hanoi in collaboration with the research team from the University of Public Health and the Citizen-Environmental science group at Live & Learn center (Live&Learn). This report is a product of the project “Improving air pollution monitoring and management of Vietnam with satellite PM₂.₅ observation”, which is part of the LASER (Long-term Assistance and SErvices for Research) PULSE (Partners for University-Led Solutions Engine) program in conjunction with United States Agency for International Development - USAID. Through this report, researchers have provided a complete picture of PM₂.₅ pollution in Vietnam with the use of multi-source data and machine learning models; as well as given assessment of the health benefits if PM₂.₅ pollution was controlled.
Researchers have analyzed the PM₂.₅ and health data across the provinces/cities in Vietnam with detailed analyses down to district level in some provinces/cities. The findings in this report can help the community as well as the authorities to gain knowledge on the air quality and take actions to improve air quality and the quality of their lives. Here are some highlights from this study/report.
General results
The level of PM₂.₅ pollution also showed changes corresponding to the level of urbanization, with the highest-ranked urban areas (namely Hanoi and Ho Chi Minh City) having less days with good air quality than other lower-ranked urban areas by 20% on average. Big cities like Hanoi and Ho Chi Minh City were hotspots for PM₂.₅ pollution in their own regions (Northern and Southern regions, respectively). In addition, the years 2020 and 2021 are considered special years in the aspect of air pollution because of the sudden events of COVID-19 and social restrictions, leading to a decrease in economic and living activities – major sources of air pollution.
Researchers also looked into impact of air pollution on the community’s health in 2019 and hypothesized what its impact would be if interventions had been applied to reduce the levels of pollution in 2019 to achieve PM₂.₅ levels similar to that of 2021. This analysis can show the impact of PM₂.₅ on people’s lives in a normal circumstance in Vietnam, and the effectiveness of interventions in controlling the anthropogenic sources. This analysis can show the impact of PM₂.₅ on people’s lives in a normal circumstance in Vietnam, and the effectiveness of interventions in controlling the anthropogenic sources. Results indicate that the estimated number of PM₂.₅-related deaths in Vietnam in 2019 accounted for one-tenth the number of deaths attributable to natural causes in Vietnam in that year; Hanoi and Ho Chi Minh City were two areas with the highest estimated numbers of deaths related to PM₂.₅ across the country. On the other hand, if interventions had been applied, the number of deaths attributable to PM₂.₅ would decrease by approximately 7%. From these findings, we hope to incentivize the authorities and the community to work on policies and take action to manage and reduce air pollution in order to improve not just the quality of the environment but quality of people’s lives.
The status of PM₂.₅ and Its Impact on human health in Vietnam in 2021
Up til now, efforts to monitor PM₂.₅ along with other pollutants are being made by the Vietnam Environment Administration at a national scale and by each province’s Department of Natural Resources and Environment at regional scale. In addition, data on PM₂.₅ are also provided by different networks of standardized monitoring stations and sensors from multiple embassies, research organizations, and private companies. In the recent years, modeling techniques using station data, satellite imagery (remote sensing) and ancillary data have been used to produce PM₂.₅ concentration maps are applied largely to provide information on PM₂.₅. This is a sufficient way to supplement for the on-ground station data, providing information on the spatial distribution of PM₂.₅ on a large scale, especially in areas that lacks on-ground measurements.
Based on current circumstances, our research will utilize modelled PM₂.₅ data to provide a more complete view of both the spatial and temporal aspect of the PM₂.₅ pollution situation in Vietnam in 2021. 2020 and 2021 were special years as there were many social distancing episodes occurring in many provinces/cities in Vietnam to limit the spread and impact of the COVID-19 pandemic, leading to a decline in PM₂.₅ emissions from human activities. The PM₂.₅ data used in this report is the map dataset of PM₂.₅distribution calculated from the Mixed Effect Model – MEM on station measurement, satellite imagery and ancillary data. The use of this data will allow for more in-depth PM₂.₅ distribution analysis nationwide and per province/city, as well as analysis into chronological trends. The findings in this report will assist in determining the provinces/cities, along with adjacent areas with critical levels of PM₂.₅ pollution that highly require policies to control and improve air quality.
Figure 1. Illustration of the size of PM₂.₅
Source: https://ww2.arb.ca.gov/resources/inhalable-particulate-matter-and-health
To achieve the research goals for this report, scientists looked at the state of PM₂.₅ pollution from different angles (PM₂.₅ pollution on a national, regional, provincial level, PM₂.₅ pollution based on urbanization, etc. as well as what harm it is causing to human health). The daily PM₂.₅ distribution maps in the period from 2019 to 2021 on a nation scale was constructed using the Mixed Effect Model and multisource data (including satellite, meteorology, and land use data). They were then aggregated to get the monthly and annual average PM₂.₅ concentration values of the provinces as well as the districts in each province to facilitate further analyses. In addition, the average levels of PM₂.₅ exposure of each province was calculated to assess how PM₂.₅ is affecting people on a provincial level. Urbanization status also correlates to the high levels of air pollution; therefore, the average PM₂.₅ levels in each urban type was also studied by extracting and analyzing daily and annual average PM₂.₅ of every area in each type.
Another aspect that needed to be assessed in the year 2021 is the possible influence of social distancing methods due to COVID-19 on the PM₂.₅ concentration, since these restrictions has reduced the economic, traffic and living activities substantially for a long period, especially in large cities where COVID-19 were most detrimental. This hypothesis was tested by looking at the changes in daily PM₂.₅ concentrations in two cities Hanoi and Ho Chi Minh during lock down in 2021. During this year, estimation was made of PM₂.₅ values in a hypothetical situation where social distancing was not accounted for (only natural factors such as meteorology) and compared with the collected dataset to reveal the effects that social distancing might have had on air pollution. After analyzing the state of PM₂.₅ in 2021, assessments were performed of its effects on human health in the year prior to COVID-19, when socio-economic activities in Vietnam were not hindered by any restriction.
Main results
Here are some core results on the status of PM₂.₅ in Vietnam from the report:
On a national scale, the annual average PM₂.₅ concentration of 2021 showed a decline compared to 2019 and a slight increase compared to 2020. Areas with high PM₂.₅ concentration were located in the Red River Delta (including Hanoi City and adjacent provinces). In 2021, there were 6 out of 63 provinces exceeding the national standard for annual average PM₂.₅ concentration (25 µg/m³). However, the levels of exposure to PM₂.₅ in the population in all provinces were higher than their annual average PM₂.₅ concentrations. Moreover, the annual average PM₂.₅ values of provinces across Vietnam were still many times higher than the WHO recommendation for 2021 (5 µg/m³).
The distribution of PM₂.₅ in each region were different with all the provinces not qualifying the national standard located in the Northern region, while the percentage of provinces satisfying the national standard for annual average PM₂.₅ in the North being only 76%, whereas the percentages of provinces satisfying the national standard in the Central and Southern regions were both 100%. When comparing average PM₂.₅ values at district level between provinces, the Northern region also showed great discrepancies between the most and least polluted areas, with values ranging from 13.1 µg/m³ to 43 µg/m³. Meanwhile, the Central and Southern regions showed less variation in their district average PM₂.₅ concentrations, with values ranging from 11.0 µg/m³ to 23.1 µg/m³ for the Central region and 11.4 µg/m³ to 21.3 µg/m³ for the Southern region.
In the aspect of urbanization, the levels of PM₂.₅ pollution had a positive correlation with the level of urbanization. Specifically, the percentage of days with good air quality in the Special type urban areas was only 64%, while this percentage for other lower urban types ranged from 79-85%. The percentages of days with air quality that is moderate and unhealthy for sensitive groups of the Special type urban areas were also higher than those of the lower type urban areas were. The two special urban areas of Vietnam, Hanoi and Ho Chi Minh City, are both the socio-economic forefronts of the country; therefore, it is reasonable that these areas would exhibit higher levels of pollution compared to other provinces in their regions.
For Hanoi, the annual average PM₂.₅ concentrations of every district in the city were higher than the national standard, with the number of days with good air quality in 2021 only accounting for 42.2% of the total days of the year. For Ho Chi Minh City, even though the PM₂.₅ concentrations all the districts in the city were under the national standard, these values were still 2 to 4 times higher than the WHO recommendation for 2021. The number of days with good air quality in Ho Chi Minh accounted for 87.1% of the total days of the year. As for the possible effects of COVID-19 restrictions on air quality, we decided to look into the air quality Hanoi and Ho Chi Minh City, which suffered the most from the pandemic with some of the longest restriction periods across the country. Although having overall high levels of PM₂.₅ in the year 2021, there were considerable drops in PM₂.₅ concentration during the lock down periods in each city. For Hanoi, when comparing the real PM₂.₅ values to our estimations under normal conditions, we noticed that the real values of PM₂.₅ about 22.7% lower during the lock down. The discrepancy was more evident in Ho Chi Minh City with a 41.4% difference between real and estimated PM₂.₅ values during the lock down. Both cities also exhibited lower levels of PM₂.₅ during the periods of social distancing compared to before and after
Besides Hanoi and Ho Chi Minh City, the status of PM₂.₅ in Bac Ninh, Thai Binh and Nghe An in 2021 was also examined. Close to Hanoi, Bac Ninh and Thai Binh are also located in the North and are characterized by the number of up-and-running industrial parks and activities in both provinces. In 2021, 100% of the districts in Bac Ninh were exceeding the national standard for annual PM₂.₅ concentration with only 49.7% of the days in this year with good air quality; meanwhile, the percentage of districts satisfying the national standard in Thai Binh was 62.5% with the percentage of days with good air quality being 69.3%. Nghe An is located in the North-Central Coast of Vietnam and is covered by a large area of natural forest; this can be beneficial for Nghe An in keeping the PM₂.₅ low but can also cause PM₂.₅ concentration to spike often via sudden forest fires. In 2021, 100% of the districts in Nghe An satisfied the national standard with PM₂.₅ concentration still higher than the WHO recommendation, and across the province, 89% of the days in this year were observed with good air quality. The distribution of PM₂.₅ in all the cities and provinces that we have looked into above shared a similarity in their seasonal variation, specifically the PM₂.₅ concentration in the winter (or dry season, typically from October or November till February or March of next year) seemed to be higher than that in summer (or wet season, typically from May to August).
Based on our PM₂.₅ distribution data for 2019, along with data from different medical facilities and population data, we estimated that there were 56.8 thousand cases of deaths due to PM₂.₅ exposure, accounting for 9.9% of the number of deaths due to natural causes in Vietnam in 2019. Regions with high number of deaths were the Red River Delta and the North-Central and South-Central Coast. Hanoi and Ho Chi Minh City were the two areas with the highest numbers of deaths estimated due to PM₂.₅ exposure with 6,250 and 4,130 cases, respectively. The number of deaths attributable to PM₂.₅ in Bac Ninh, Thai Binh and Nghe An were 1,047, 1,697 and 1,930 cases. Moreover, according to our estimations, if intervention measures were applied to make PM₂.₅ levels in 2019 to decrease to levels similar to that of 2021, then the number of deaths due to PM₂.₅ would decrease by 6.7% across the country.
Specifically, the number of deaths attributable to PM₂.₅ per district in Hanoi would decline by 5.6-6.8%, while Ho Chi Minh would decrease by 6.9% the total number of deaths due to PM₂.₅ of the whole city. Bac Ninh province would be able to cut from 5.1-5.8% of its number of deaths per district, and Thai Binh would be able to reduce 6.1% of its total number of deaths. As for Nghe An, the number of deaths attributable to PM₂.₅ per district of the provinces would be reduced by 5.1-7.4%
Recommendations
With evidence of the effects of PM₂.₅ on human health that we have presented, we recommend that there should be a joint effort between multiple parties (scientists, researchers, government bodies, NGOs, private sectors, the community, etc.) to take action in order to manage and reduce air pollution so that the quality of the environment as well as quality of people’s lives can be improved.
For organizations and government units, the use of PM₂.₅ dust distribution maps from the model is highly recommended and, in the future, can be extended to other pollutants for a comprehensive view of the current state of air quality at the national, regional, and provincial levels every year. In addition, priority should be given to monitoring and managing (including the development of a standard air monitoring network) and the development of air quality management plans for provinces and cities and urban areas with high levels of pollution as detailed in this report. In addition, the development of a mechanism to share data and information for quality assurance/control at stations for scientific research and education-communication activities. In addition, there is a need for periodic review and updating of the national air quality standards, as there is currently a large gap between the national standard and WHO recommendations, which refers to the PM₂.₅ level that can start to cause harm to human health. Besides national standards for ambient air, Vietnam also needs standards for indoor air pollution as this is also an urgent problem in middle-and-low-income countries. In addition to air quality management, we also recommend periodic monitoring of the effects of air pollution on health because the results from this assessment will also be a useful source of data to help quantify the effectiveness of the policies being implemented. In addition, it is also necessary to improve the system of recording deaths and illnesses at health facilities for timely and complete updates. Furthermore, there is a need for inter-disciplinary cooperation (in particular, air quality management agencies and health facilities together with population statistics agencies) to ensure efficiency in assessing the level and impact of air pollution on the health of the community.
As for research institutes and universities, we recommend that there be research investment in air pollution modeling at national, regional, and city/province scale to provide data of either the status or forecast of air pollution with high accuracy. In addition, it is also necessary to develop a method for assessing the health impact of air pollution specifically for Vietnam, to increase the accuracy of the assessment. With the status of PM₂.₅ dust pollution, it is necessary to develop methods to identify accurately the sources of pollutant emissions from which to take reasonable mitigation measures. Finally, in each stage of the research and evaluation process, it is necessary to consult experts as well as state management agencies to ensure the quality of the process as well as the correctness of the result interpretation. This will also provide more information and strengthen the interest and commitment of regulatory agencies to the application of research results to management activities.
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