Spring has already arrived. However, as the warm season begins and the ground thaws, the cases of hand, foot, and mouth disease tends to increase, becoming a common occurrence. Although invisible to the naked eye and imperceptible to touch, soil pollution has significant adverse effects on human health. To understand what soil pollution is, how it impacts human health, and ways to prevent it, we spoke with U.Ganzorig, Head of the Soil Science Division at the Institute of Geography and Geoecology of the Mongolian Academy of Sciences.

In recent years, people have become highly concerned about air pollution. At the same time, experts in the field have been warning that soil pollution has also reached disaster levels. Is that correct?

Soil is one of the most crucial components of the ecosystem and serves as the foundation of life. It is also essential to our daily lives. For example, approximately 98 percent of the food we consume is produced directly or indirectly through soil. Therefore, if we fail to protect and preserve our soil, we risk compromising food and nutritional security in the future. Soil is a living system—one teaspoon of soil contains microorganisms equivalent in number to the world’s human population. This means that soil is a dynamic and complex living ecosystem. Unfortunately, in recent years, Mongolia has primarily focused on air and water pollution, often neglecting soil-related issues.

 What are the main factors contributing to soil pollution?

In its natural state, soil does not have pollution. Pollution occurs when soil becomes contaminated with various substances, chemical elements, or human-induced pollutants. In Mongolia, the two primary categories of soil pollutants are heavy metals and bacterial contaminants. Heavy metals refer to elements that contribute to soil contamination. For instance, in natural soil, arsenic, lead, zinc, nickel, and chromium exist in relatively low concentrations. However, due to human activities, soil is increasingly becoming contaminated with these elements, a process known as heavy metal pollution.

In Ulaanbaatar City, bacterial contamination is more widespread, especially in ger districts, whereas heavy metal pollution is more localized, affecting specific areas. For example, areas with high heavy metal contamination include the Khargia sewage treatment plant, the “Da Khuree” market, recycling plants in Nalaikh District, and secondary raw material collection sites in the capital city center.

Is the increase in bacterial contamination in ger districts primarily caused by pit latrines?

The primary source of bacterial contamination in Ulaanbaatar is, indeed, pit latrines used by households in ger districts. Various types of bacteria originating from these latrines are found in the soil. In addition to pit latrines, improper waste disposal is also common in ger districts, where some areas have makeshift dumping sites. As a result, both bacterial and heavy metal contamination can be detected in these locations. Furthermore, people often dispose of ashes and wastewater outside their fences, further contributing to soil pollution.

That said, these issues have somewhat decreased in recent years, largely due to improvements in infrastructure. Areas with well-developed infrastructure, including roads and proper facilities, tend to have lower instances of such pollution, as residents do not dispose of waste haphazardly. However, in suburban and peripheral ger districts with poor infrastructure and limited oversight, such pollution remains prevalent. In apartment complexes, soil contamination is relatively low, except in areas near open dumpsites or secondary raw material collection points, where pollution is still significant.

What negative impacts does this type of pollution have on human health?

Bacterial contamination becomes a major concern when the weather warms, particularly during spring, when cases of intestinal infectious diseases surge. This rise is directly linked to the contamination caused by pit latrines. Recent studies have shown that the soil within household plots in Ulaanbaatar’s ger districts is heavily contaminated with bacteria. Our research revealed that bacterial contamination from a single household’s pit latrine extends up to 25 meters in all directions. Given that the standard household plot size in Ulaanbaatar is around 0.07 hectares—approximately 25x25 meters—this means that the entire plot is effectively contaminated. Consequently, the outbreak of intestinal infectious diseases in spring is inevitable. Children, who are in closer contact with soil, face the greatest risk of exposure.

Moreover, heavy metal contamination poses an even greater threat than bacterial pollution. When accumulated in the body over time, heavy metals can affect genetic material and significantly increase the risk of developing cancers. The specific health risks depend on the type of heavy metal involved.

It has been mentioned that heavy metal pollution has decreased compared to previous years. Could you elaborate on this?

The Soil Science Division of the Institute of Geography and Geoecology at the Mongolian Academy of Sciences has been conducting soil contamination studies across Ulaanbaatar since 1989. Detailed investigations were carried out in Chingeltei District in 2003, and across the capital city in 2010 and 2015. Most recently, last year, the Ministry of Environment and Climate Change conducted a comprehensive study at 330 sites throughout Ulaanbaatar.

The findings revealed that soil degradation and loss of natural characteristics due to human activities such as road construction, transportation, and urban development are widespread. When comparing the samples from these 330 sites to the natural baseline soil composition, arsenic levels were found to be 89 percent higher, lead 80 percent higher, zinc 68 percent higher, chromium 27 percent higher, and nickel 15 percent higher. In other words, Ulaanbaatar’s soil is significantly more polluted than natural soil. However, when compared to Mongolia’s national soil contamination standards, the pollution levels are relatively lower, with approximately 0.3 to five percent of the samples exceeding acceptable limits. Specifically, five percent of the samples showed arsenic concentrations beyond the permissible level, while 2.1 percent had excessive zinc, 1.8 percent exceeded lead limits, and 1.2 percent had copper levels above the standard threshold.

Heavy metal contamination tends to be concentrated around specific sites. For example, chromium pollution is particularly severe near the Khargia sewage treatment plant, while lead contamination is notably high in Nalaikh District due to the presence of a battery recycling facility. Encouragingly, overall heavy metal pollution has shown a slight decline compared to previous years.

What contributed to this reduction in pollution? Were specific measures implemented?

In recent years, infrastructure in Ulaanbaatar has improved, with the construction of new roads and other developments. Public awareness has also increased, leading to a reduction in illegal dumping, which has contributed to the slight decrease in soil contamination.

However, the situation with bacterial contamination remains concerning. As long as pit latrines are in use, bacterial pollution cannot be eradicated. The 2015 study indicated that approximately 88 percent of the 330 surveyed sites showed signs of bacterial contamination—a figure that remained unchanged in last year’s assessment. Ulaanbaatar currently has 144,990 pit latrines, and reducing this number is key to lowering bacterial contamination levels.

Which areas experience the highest levels of bacterial contamination?

Bacterial contamination is most prevalent in areas with dense ger district populations, such as Denjiin Myanga, Zuragt, and Bayankhoshuu. Studies conducted in 2011, 2013, 2015, and 2024 consistently highlighted these regions as hotspots for contamination. On a positive note, in recent years, residents of Songinokhairkhan and Chingeltei districts have begun replacing traditional pit latrines with improved sanitation systems, raising hopes for reduced contamination in the future.

Has a detailed soil pollution study been conducted at the local level?

Then Ministry of Environment and Tourism conducted a nationwide study last year, covering around 1,100 sites across the 21 provinces and the nine districts of Ulaanbaatar. The results showed that soil pollution in the capital city was significantly higher compared to the provinces. In provincial centers and larger settlements, pollution was detected at relatively fewer sites.

People don’t usually take soil pollution seriously, yet I’ve heard that it can even spread through insects. Is that true?

When the soil is contaminated, the water inevitably becomes polluted too. As we rely on that water for consumption, it poses a direct threat to our health. Pollutants in the soil can become airborne due to natural and human activities, spreading through the air we breathe. Additionally, various insects and rodents act as carriers, transmitting infections to humans. For example, flies can carry bacteria and pathogens from contaminated soil and spread them through airborne droplets. When soil pollution reaches critical levels, measures must be taken to mitigate it. Failing to do so exposes us to increased risks, especially in spring and autumn when unstable air flows stir up dust and particles from polluted soil.

Take, for instance, the Central Wastewater Treatment Plant in Ulaanbaatar. Numerous concrete mixing plants, gravel quarries, and recycling facilities are situated near the plant, directly in the path of the city’s prevailing winds. As a result, residents are at high risk of inhaling particles from contaminated soil. On windy days, the stench from the plant can be overpowering, making it clear that we are already breathing in pollution. Similarly, the Ulaanchuluut and Moringiin Davaa landfills are located upwind of the city, yet few people take notice of this.

Flooding is another major risk factor, capable of spreading bacterial contamination over vast areas. Do you remember the 2023 floods in Dari-Ekh? Many household pit latrines were swept away, spreading contamination across the flooded areas.

What measures can be taken to reduce soil pollution? Are there any methods to rehabilitate polluted soil?

Our soil scientists have been conducting research over the past two years, commissioned by the then Ministry of Environment and Tourism, on using plants to reduce heavy metal contamination in the soil. The focus has been primarily on chromium and lead contamination. Through these studies, we’ve determined that common plants like sunflowers, dandelions, and mustard—all of which grow well in Mongolia’s climate—can reduce heavy metal pollution by 15 to 40 percent. In other words, individuals and businesses can use specific plants to help cleanse the soil. We plan to release guidelines on this method within the year.

Preventing soil pollution, however, ultimately comes down to personal responsibility. Something as simple as not littering prevents further contamination. Moreover, transitioning away from pit latrines that allow direct seepage into the soil is crucial. Alternatives such as lined pits, vacuum-pumped systems, or bio-toilets can significantly reduce bacterial contamination.

Infrastructure improvement also plays a key role. For example, the notorious “Mangasiin Am” area near Narantuul Market was once a hotspot for various types of pollution. Now, that area has been paved over with a road, which reduced the risk greatly. Expanding road networks and green spaces discourages littering and public defecation, further protecting the soil.

Moreover, integrating soil-related topics into the natural sciences curriculum of schools is essential. Educating children—the future guardians of our environment—will not only raise awareness but also help mitigate risks across Ulaanbaatar and the entire nation, including the 21 provinces and its 330 soums.

By D.CHANTSALMAA