New study reports a significant increase in ADHD rates among children exposed to certain air pollutants before birth and who suffer hardship at home as children.

Breathing dirty air and living in stress combine to increase the likelihood NYC kids will have a behavior disorder.

That’s the message from a new study that found black and Dominican children who suffer from high prenatal air pollution exposure and a lack of food, clothing and shelter have significantly higher rates of ADHD.

The study, published today in the journal Environmental Research, is the first to suggest that polycyclic aromatic hydrocarbons (PAHs)—common contaminants in city air from burning fuels such as diesel, coal, gas, oil—combined with a hard home life may bring about behavioral problems.

“A lot of people in the most polluted communities already talk about this, how pollution stresses pile on top of life stress,” said Molly Rauch, public health policy director at Moms Clean Air Force, a national nonprofit organization focused on air pollution, climate change and kids’ health.

However, “showing that interaction is really important to get a better handle on how low income communities are impacted,” said Rauch, who was not involved in the study.