Impaired vision in children is generally linked to congenital conditions or trauma-induced injuries to the brain or face. In a new study conducted in China, researchers have now found a new environmental link to impaired vision.

A study published in PNAS Nexus found that exposure to air pollutants, especially nitrogen dioxide and fine particulate matter, may be a cause of nearsightedness, also called myopia. The study was conducted on 30,000 schoolchildren in Tianjin, China, and combined environmental, lifestyle, and genetic data in a machine-learning model. It concluded that genetics were the main driver of reduced vision, but children living in areas with lower air quality had worse vision than those living in areas with better air quality.

Zongbo Shi, lead author and professor of atmospheric biogeochemistry at Britain's University of Birmingham, said in a statement to The Washington Post: "We showed that air pollution contributes to myopia development in children. What this means is that if their exposure to air pollution is high, the risk to become shortsighted is higher."

The study included "clean air" simulations that reduced levels of fine particles (PM2.5) and nitrogen dioxide, and found that students' vision improved, especially among primary-school children, who showed nearly double the improvement compared to older students.

In addition to air pollution, more data has shown that sleep deprivation and increased screen time were also contributing factors to reduced vision.

The study did not assess short-term air pollution, like that from wildfire smoke. This study joins others, such as one led in Denver that found air pollution was associated with higher ophthalmology visits and eye inflammation, and a clinical practice study that found that air pollutants increased the risk of myopic progression in children.

Every organ in the body can be impacted by air pollution, according to the World Health Organization. Pollution leads to inflammation, immunosuppression, and mutagenicity in cells. It ups the risk of heart disease, lung damage, brain damage, and stroke.

The reason air pollution is so damaging is that the particles are small enough to enter our bloodstream through our lungs, leading to chronic inflammation and increased cancer risk.

Pregnant people also have an increased risk for adverse pregnancy outcomes, such as lower birth weight and cognitive impairment.

Air pollution has to be addressed systemically and locally. Reducing harmful carbon pollution by switching from gas-powered vehicles to electric cars, trucks, and trains would make a vast impact.

Shi agreed that policy change is essential to reduce air pollutants, saying, per the Post: "Reducing exposure is the key."