Scientists have long puzzled over the cause of peanut allergies, especially those that don’t resolve themselves with age. (Photoroyalty/Shutterstock)

PARKVILLE, Australia — Every breath we take contains a complex mixture of particles and gases, many invisible to the naked eye but potentially consequential for our health. A new study from Australia has revealed a surprising connection between these everyday air pollutants and one of childhood’s most feared health conditions: persistent peanut allergies. As rates of food allergies continue to climb worldwide, this research suggests we may need to look beyond our plates and into our atmosphere for answers.

Most parents are familiar with the anxiety surrounding peanut allergies. The possibility of a severe reaction from even minimal exposure has changed school policies, birthday party planning, and flight snack options across the globe. But why some children develop these allergies while others don’t has remained something of a medical mystery. Genetics plays a role, certainly, but environmental factors may be equally important.

According to new research published in the Journal of Allergy and Clinical Immunology, higher exposure to common air pollutants during early life is associated with an increased prevalence of peanut allergy—and perhaps more troublingly, with allergies that persist throughout childhood rather than resolving naturally as children age.

Linking Air Pollution To Peanut Allergy

The study, conducted by a team led by Diego J. Lopez at the University of Melbourne and the Murdoch Children’s Research Institute (MCRI), tracked more than 4,600 Australian children initially, with about 2,900 remaining through age ten. What makes this research particularly significant is its methodological rigor. Unlike previous studies that relied on self-reported allergies or basic blood tests, this one used the gold standard of allergy diagnosis: oral food challenges, where children consume potentially allergenic food under medical supervision to confirm whether a true allergy exists.

“This is the first study to use an oral food challenge, the gold standard of food allergy diagnosis, to investigate the relationship between food allergy and air pollution,” says study author Rachel Peters, an MCRI associate professor, in a statement.

Air pollution is often discussed in terms of its respiratory effects, but its impact may be far more wide-ranging than previously understood. The research team focused on two common air pollutants: nitrogen dioxide (NO₂), which primarily comes from vehicle exhaust and power plants, and fine particulate matter (PM₂.₅), which consists of tiny particles that can penetrate deep into the lungs and even enter the bloodstream. These pollutants can also potentially disrupt the skin barrier, which is particularly relevant to how food allergens may enter the body and trigger sensitization.

Children exposed to higher levels of these pollutants during their first year of life showed significantly higher rates of peanut allergy at ages one, four, six, and ten. For instance, those exposed to high concentrations of NO₂ (≥10 ppb) at age one had 2.21 times higher odds of peanut allergy at age one and 2.29 times higher odds at age four compared to those with lower exposure. Similarly, increased PM₂.₅ exposure at age one was associated with higher peanut allergy rates at ages four, six, and ten.

‘Inflammatory Effect’ Of Dirty Air

Perhaps most concerning is the finding regarding persistent allergies. Children exposed to higher pollution levels were not only more likely to develop peanut allergies but were also more likely to have allergies that persisted throughout the entire study period rather than resolving naturally, which is the normal pattern for many childhood food allergies.

Interestingly, this relationship was specific to peanut allergy. The researchers found little evidence connecting air pollution with egg allergies or eczema, suggesting something unique about how peanut proteins interact with the body’s immune system in the presence of pollutants.

“Air pollutants have an irritant and inflammatory effect that may boost the immune system’s pro-allergic response, potentially triggering the development of food allergies,” says study author Diego Lopez, Ph.D., from the University of Melbourne. “However, the underlying mechanisms of how air pollution increases the risk of a peanut allergy, and why eczema and egg allergy aren’t impacted in the same way, need to be explored further.”

“The rise in allergy prevalence has occurred at a similar time to increased urbanization, leading to the belief that environmental factors may be contributing to high allergy rates,” adds Peters. “Eczema and food allergy most often develop in infancy. Both immune conditions can naturally resolve over time, but for some, they can persist throughout adolescence and into adulthood.”

Surprise From Down Under

Interestingly, the findings emerged from Australia, where air pollution levels are generally lower than in many other countries. Peters pointed this out, saying the study found higher levels of air pollution were a risk factor for the development and persistence of peanut allergies despite Melbourne having generally good air quality compared to our international counterparts. If these associations are present even at relatively low pollution concentrations, the implications for children in highly polluted urban areas worldwide could be significant.

The study also revealed an interesting interaction with environmental greenness. Children living in greener areas with high pollution levels had a higher risk of food allergies at ages 1 and 6, while those in low-greenness areas with high pollution had a lower risk at age 6. This complex pattern suggests that the relationship between environmental factors and allergy development is multifaceted and may involve how much time children spend outdoors in different settings.

For parents and healthcare providers, these findings provide new insights into risk factors for one of childhood’s most worrisome allergies. They suggest that reducing air pollution exposure, particularly during the critical first year of life, could potentially reduce the development and persistence of peanut allergies.

“The research highlights the importance of early-life interventions aimed at reducing exposure to air pollution, which could potentially prevent peanut allergies and other poor child health outcomes,” says Peters. “Improving city design to support greater air quality regulation, better promoting public transport, and switching to non-combustion fuels may help turn the tide on peanut allergy.”

Mae’s Story

The real-world impact of food allergies is illustrated by the experience of 8-year-old Mae, who was diagnosed with peanut, dairy, and egg allergies at 8 months old after breaking out in hives across her entire body. She has since experienced several anaphylactic reactions. Her mother, Eleanor Jenkin, recounted a particularly severe episode that occurred five years ago during a food challenge at The Royal Children’s Hospital to check Mae’s tolerance for reintroducing egg into her diet.

“She was eating cupcakes as part of the challenge until she started to refuse to eat anymore,” says Jenkin. “We thought she was just being fussy, but she began vomiting and lost consciousness. It was her first anaphylaxis and while it was scary, she returned to her normal self a few minutes after being given an adrenaline shot.”

Mae now carries an EpiPen at all times. The family was hopeful that she would outgrow food allergies with age, but has come to accept that it is something Mae will have to deal with for her life.

“Her allergies are always going to be in the back of her mind, influencing the decisions that she makes every time she eats at a restaurant, orders takeaway, or goes to a birthday party. As a family we are learning to manage this new normal as best we can,” says Jenkin.

The Fight Against Peanut Allergies

Allergic disease represents one of Australia’s greatest public health challenges, with one in 10 children developing a food allergy in their first year of life. This statistic underscores the urgency of understanding all potential contributors to this growing problem.

The authors note that if these findings apply to countries with higher pollution levels, air pollution may be contributing significantly to the growing burden of food allergies globally. This could be particularly relevant in rapidly urbanizing regions where pollution levels are increasing.

While this study represents a major advance in our understanding of environmental risk factors for food allergies, many questions remain. Why does pollution specifically affect peanut allergy but not egg allergy? How exactly do pollutants interact with the immune system to promote allergic reactions? Could interventions to reduce pollution exposure in early life help prevent food allergies?

Research in this area continues to expand. The GenV study, which tracks the health and well-being of those who live in Victoria, Australia, from birth to old age, is also beginning to examine the impact of air pollution and climate change on children’s health. With data from more than 120,000 participants, including 48,000 babies, this research may provide further insights into how environmental factors affect allergy development.

MCRI Associate Professor Suzanne Mavoa noted that this ongoing research would improve our understanding of how climate change impacts the health of children and families, identify those most at risk, and test policies and interventions to better protect against severe weather events.

As the prevalence of food allergies continues to rise worldwide, understanding environmental contributors becomes increasingly important. This study offers compelling evidence that the air we breathe may play a significant role in determining which children develop peanut allergies and whether those allergies persist throughout childhood.

For now, the findings serve as a reminder that environmental health and human health are inextricably linked. The next time you see exhaust billowing from a tailpipe, consider that its effects may extend far beyond air quality—all the way to food allergies that can dramatically affect a child’s quality of life.