Apr 10, 2026

The Air They Share: How Air Pollution Harms Pregnant Women and Young Children

by Maya Havenwood

Air pollution is most harmful to people who are already vulnerable, including children, the elderly, and pregnant women. Although many studies examine the way that air pollution can affect young children, fewer studies focus on the way maternal exposure to air pollution affects both pregnant women and their offspring. This article will summarize research from three studies to address:

How exposure to air pollution affects pregnant women and their offspring
How exposure to air pollution affects infants and children
How HEPA air purifiers can mitigate the effects of air pollution on pregnant women and their offspring

How can exposure to air pollution affect pregnant women?

During pregnancy, women experience many metabolic changes which make them more vulnerable to negative effects from air pollution. One such effect is pregnancy-induced hyperventilation, a tendency to breathe more rapidly during pregnancy due to increased oxygen demands. This hyperventilation “may lead to inhalation of more ambient toxic substances”. When a pregnant woman breathes in polluted air, it may have long-lasting repercussions on both her health and the health of her unborn child. According to the World Health Organization, “Maternal exposure to air pollution is associated with adverse birth outcomes, such as low birth weight, pre-term birth and small for gestational age births.”

In addition to physical repercussions, air pollution can also have a negative effect on maternal mental health. A 2023 article in the Journal of the American Medical Association finds that women who were exposed to air pollution during pregnancy were at higher risk of postpartum depression after giving birth.

Postpartum depression, a form of major depressive disorder, affects some women in the weeks and months after giving birth. Symptoms of postpartum depression include mood swings, withdrawal from loved ones, and severe anxiety. Postpartum depression, one of the most frequent childbirth complications, affects approximately 20% of women worldwide. In addition to the immediate negative symptoms experienced by mothers with PPD, infants born to mothers with this diagnosis may be at a higher risk of developing cognitive and emotional impairments.

In this study, the authors analyze potential connections between air pollution and PPD using data from 340,000 women who gave birth during an eight-year span in Southern California. These women were screened for postpartum depression using a standard testing metric, and those who tested positively for PPD were referred to a clinical interview for further assessment and care.

The authors studied the correlation between instances of PPD and the levels of air pollution that each woman was exposed to during pregnancy. They collected the home address of each woman, and they used data from the US Environmental Protection Agency’s monitoring stations to estimate the exposure they each experienced on a daily basis.

The study found that long-term exposure to air pollution during pregnancy is associated with an increased risk of postpartum depression. It specifically focused on the implications of three types of pollution: O3, PM10, and PM2.5.

O3 is ozone. When ozone is at ground level, it is a pollutant that can harm people and animals. Pollutants from cars, power plants, and other sources chemically react in sunlight to create ground level ozone, which is the main ingredient in smog. Ozone most often reaches unhealthy levels on hot days in urban environments, but it can still reach high levels during colder months. O3 exposure during the entire pregnancy is associated with increased risk of postpartum depression

PM10 is particulate matter that has a diameter of 10 microns or less. This pollution often comes from dust from construction sites, wildfires, and landfills. Exposure to PM10 during the late pregnancy and postpartum periods is associated with an increased risk of postpartum depression.

PM2.5 is particulate matter that has a diameter of 2.5 microns or less. The microscopic size of PM2.5 allows it to travel deep into the lungs and enter the bloodstream, where it can affect organs like the heart and the brain. This pollution often results from burning gasoline, oil, or wood. Similar to exposure to PM10, exposure to PM2.5 during the late pregnancy and postpartum periods is associated with an increased risk of postpartum depression.

The authors propose several methods to shield pregnant women from the harmful effects of air pollution. They point out that the most influential timeframe is during late pregnancy and after delivery. They recommend:

Purposeful use of air purifiers
Avoidance of outdoor activity on smoggy days
Avoidance of major sources of air pollution

When considering the effects of air pollution, we need to examine all at-risk populations, and we need to consider mental as well as physical effects.

How can exposure to air pollution affect children?

We already know how tobacco smoke harms children. The CDC explains that although secondhand smoke harms everyone, infants and young children experience more significant damage because their bodies are still growing. When infants are exposed to secondhand smoke, they are at a higher risk for asthma, respiratory infections, slowed lung growth, and other negative effects.

As a society, we’ve taken steps to reduce the harm that tobacco smoke can cause children. Public schools are tobacco-free environments, and smoking is often banned indoors and within 20 feet of building entrances.

New research suggests that there’s another risk factor that could have effects as serious as secondhand smoke: air pollution. Like tobacco smoke, air pollution – particularly fine particulate matter, or PM2.5 – leads to harmful health outcomes for children.

PM2.5 consists of tiny airborne particles, each less than 2.5 micrometers in diameter. This type of air pollution primarily comes from burning coal and other fossil fuels, vehicle emissions, and industrial emissions, although there are a variety of other human and natural sources. Breathing in PM2.5 can make you sick in a number of ways. Short-term exposure can aggravate allergies, asthma, and bronchitis, and it can cause nose, ear, and throat irritation. Long-term exposure can contribute to heart disease, lung disease, low birth rate, and reduced life expectancy. Like tobacco smoke, air pollution caused by PM2.5 is particularly harmful to people who are already vulnerable, like children and the elderly.

The risks of PM2.5 begin even before birth. When expecting mothers are exposed to fine and ultrafine particle matter, their children’s health is later negatively affected. These effects mirror those created by secondhand smoke: they impact children’s respiratory systems, immune status, and brain development.

As research has shown how secondhand smoke harms children, we have made a concerted effort to protect children from smoke through laws, regulations, and a significant culture shift away from cigarettes. Current regulations on tobacco use ensure clean air in schools, buildings, and parks where children play.

Now that we know there’s another type of pollution that’s just as harmful to children, we have a responsibility to take action to protect them. But this problem is more complicated: PM2.5 isn’t created by individual people, and a simple “No Smoking” sign won’t address the various industrial and agricultural sources of this pollution. Regulations, like the regulations we currently have on tobacco products, would likely help reduce harm. Ideal regulations would limit the amount of pollution that industries or cars can release into the environment.

The authors of a 2021 article from the journal Environmental Health and Preventative Medicine conclude that “policies to reduce maternal exposure and health consequences in children should be a high priority.” They demonstrate that proximity and access to green space provides health benefits to residents. They suggest that policies that expand green space, and enable access to green space, might help groups who are disproportionately affected by these compounds.

Although effective policies to reduce air pollution will protect vulnerable groups in the future, it is essential to mitigate negative effects of the air pollution that already exists. Luckily, air purifiers can effectively reduce exposure to air pollution.

What are HEPA filters?

HEPA (High-Efficiency Particulate Air) filters are usually made of either glass or synthetic fibers aligned randomly to catch particles of various sizes. They are fitted into an air purifier, an appliance that also contains a fan and housing. A high-quality HEPA air purifier can pull particles like smoke, pollen, viruses, bacteria, and atmospheric particulate matter (PM2.5 and PM10) out of the air.

Can HEPA filters meaningfully reduce the effects of air pollution on pregnant women and their children?

A 2022 study attempts to answer this question by turning to one of the world's most polluted cities. The objective was to identify how portable air purifiers, fitted with HEPA filters and used during pregnancy, would affect children's cognitive performance in childhood. This is a developing area of research: the authors write that, to their knowledge, this is the first randomized controlled trial of reductions in air pollution during pregnancy and cognitive performance in childhood.

The researchers focus on a group of 540 mother/child pairs in Ulaanbaatar, the capital city of Mongolia. This city has some of the worst air quality in the world, consistently measuring more than 10 times the World Health Organization’s recommended guidelines. The researchers randomly divided the participants into either a control group or an intervention group. They installed air purifiers with HEPA filters in the homes of the mothers in the intervention group and encouraged them to run the purifiers continuously. The mothers in the control group did not receive air purifiers. After the women gave birth, the researchers removed the air purifiers from their homes.

The researchers tested both groups consistently for several years after the children were born. They administered questionnaires and visited their homes to test for PM2.5 levels and to assess the quality and quantity of nurturing and stimulation in each home. At the four-year mark, the researchers measured the children’s cognitive performance using the Wechsler Preschool and Primary Scale of Intelligence, Fourth Edition, which is a measure of cognitive functioning in children that has been widely used in studies of environmental hazards. They conducted several sub-tests, then combined these scores to determine each child’s full-scale intelligence quotient (FSIQ), which indicates general intellectual functioning.

“reducing PM air pollution exposure during pregnancy could be beneficial for cognitive development.”

CONCLUSION

To fully understand the implications of air pollution, we need to examine both physical and mental effects on a variety of at-risk populations. By uncovering the effects of three types of pollutants (O3, PM2.5, and PM10) on young children and pregnant women, we can build a comprehensive understanding of effects so we can determine the best way to remediate. The studies outlined in this article demonstrate:

Pregnant women and children are particularly vulnerable to air pollution
Air pollution can lead to postpartum depression in women
Air pollution experienced by pregnant women can lead to lower cognitive scores in their children
Air pollution can have effects on children similar to the effects of tobacco smoke
Use of HEPA air purifiers during pregnancy is associated with improved cognitive performance in children

The science is still evolving, but the message is clear. Pregnant women and children are particularly vulnerable to the effects of air pollution, and steps like using HEPA air purifiers at home can help reduce exposure while broader policy changes continue to develop.