Can clean air increase child IQ?

Intellectual Quotient (IQ) is an imperfect predictor of many outcomes, such as academic performance and lifetime earning potential. But researchers continue to find a correlation between air quality and children’s performance on IQ tests.

The accuracy of IQ test scores as direct indicators of future academic and financial success is controversial. Indeed, IQ tests vary in competency and don’t always accurately portray the intelligence of an individual. However, many experts still find it be a valuable measurement tool (1).

Studies show that breathing polluted air can impair memory and reasoning, reduce academic performance, and even lower intelligence. And sure, it’s not hard to imagine that clean air can prevent the lowering of a child’s IQ by avoiding the detrimental effects of breathing air pollution — but can clean air actually increase your child’s IQ?

Air quality and child IQ test scores

Living in a polluted area as a pre-teen and teenager may have long-lasting, detrimental effects on a person’s ability to reason and problem-solve.

For every 2.5 µg/m3 increase of PM2.5 surrounding teens’ homes, their performance IQ score dropped one point.

In one study, researchers found that, for every increase of 2.5 micrograms per meter cubed (µg/m3) of fine-particle pollution (PM2.5) surrounding the teens’ homes, their performance IQ score dropped one point (2).Note that performance IQ measures reasoning and problem-solving abilities — this is a different measurement than verbal IQ, which measures acquired knowledge, verbal reasoning, and attention to verbal materials (3) (4).

“Verbal IQ is something you can learn, and once you learn, you know that for your lifetime. But performance IQ is about your ability to solve new questions, new problems. That’s more controlled by your brain function,” said Pan Wang, a statistician based at the University of California, Los Angeles who acted as lead author on the study.

Air pollution may have adverse effects on brain structure.

He continued, “The findings from this study indicate the adverse effects of air pollution are at a higher level in the brain and may have adverse effects on the brain structure or brain function.”

Child IQ and prenatal exposure to air pollution

The developing fetus and young child are especially vulnerable to neurotoxicants, such as polycyclic aromatic hydrocarbons (PAHs) released during the combustion of fossil fuels and other organic material.

Two long-term studies have revealed that common air pollutants breathed by pregnant women may be reducing their children’s intelligence. The studies involve more than 400 women in two cities — New York City and Krakow, Poland (both well established as heavily polluted urban areas).

Researchers found that 5-year-olds whose mothers had above-average exposure to PAHs score about four points lower on IQ tests than children whose mothers had below-average exposure (5).

Poor air quality exposure and student GPA

The relationship between children’s health and academic achievement has consistently been highlighted in studies that demonstrated that poorer health status is associated with poorer academic achievement outcomes (6).When children are unhealthy, they may have more difficulty learning and have poorer academic achievement outcomes than their healthy counterparts (7).

Of course, it’s difficult to separate the many factors that influence academic achievement. But researchers are finding that, in addition to health status, poor residential Indoor Air Quality also negatively affects GPA.

The impact of airborne pollutants in the home on student GPA is significant, even when accounting for health status. Children who were exposed to high levels of motor vehicle emissions from cars, trucks, and buses on roads and highways were found to have significantly lower GPAs, even when accounting for other factors known to influence school performance (8).

And worse yet — higher school-based hazardous air pollution (HAP) levels are found to be associated with lower individual-level grade point averages. Another study found that fourth and fifth graders who are exposed to toxic air pollutants at home are more likely to have lower GPAs (9).

Children exposed to high levels of vehicle emissions were found to have significantly lower GPAs, even when accounting for other factors.

These findings indicate the need for regulations on school siting and adjacent land uses to protect children's health.

Air quality and standardized test scores

Multiple studies have identified a link between air quality and performance on standardized tests (10). For example, one study of school children in Southern California found that exposure to higher levels of fine particulate matter (PM2.5) is linked to consistently lower scores on standardized tests in math and reading (11).

Air quality and cognitive development

Studies have also associated poor Indoor Air Quality with a decrease in students’ ability to perform specific mental tasks requiring concentration, calculation and memory.11

There is also mounting evidence that poor IAQ can cause verbal, perceptual, motor, and behavioral disabilities in children. It can also cause hearing impairment, irritability, and developmental delays.

Ventilation effects on standardized test scores

Most schools’ ventilation rates are below recommended levels. Adequate air ventilation rates can improve test scores and student performance in completing mental tasks. For every unit (1 liter per second per person) increase in the ventilation rate within that range, the proportion of students passing standardized tests is expected to increase by 2.9% for math and 2.7% for reading (12).

For every unit increase (1 liter per second) in ventilation, the proportion of students passing tests increases by 2.9% for math and 2.7% for reading.

There’s also a statistically significant association between ventilation rates and mathematics scores. In one study, students' mean math scores increased by up to eleven points (0.5%) for every increase in ventilation rate of one liter per second per person (13).

In another study, students in classrooms with higher outdoor air ventilation rates scored 14 to 15 points higher on standardized tests than children with lower outdoor air ventilation rates (14).That’s an entire letter grade and a half!

What you can do

Each of us plays an essential role in taking action to clean the air we breathe indoors and outdoors.

We can help reduce the sources of pollution, better ventilate our indoor environments, and provide air filtration for schools and other indoor environments as needed. Here are a few examples of the positive steps we can each take to clean the air and keep ourselves safe from air pollution:

  • Get involved at school. Many schools haven’t upgraded their facilities in decades. Join your school’s parent-teacher association (PTA) or school board to get involved in improving your school’s air quality. IQAir can help reduce classroom pollutants by at least 90 percent. Visit to read our pilot study on classroom air filtration.
  • Monitor your Indoor Air Quality (IAQ). AirVisual Pro by IQAir lets you monitor pollutants in your indoor and outdoor air so that you know precisely when air quality is bad. Encourage your school to set up air quality monitors, too. This way, teachers can take appropriate action to increase time indoors when air quality is bad. The AirVisual Pro also monitors CO2 levels, so teachers can know when it’s time to ventilate the classroom.
  • Avoid unnecessary exposure at home: Avoid unnecessary exposure by using a high-performance air purifier, such as the IQAir HealthPro® Plus room air purifier or the Perfect 16® whole-house air purifier.
  • Use a high-powered personal air purifier, such as the Atem® Desk, where your child studies. Students can ensure they are breathing clean air, no matter where they are.
  • Wear an air pollution mask when pollutants are unavoidable. Have your child wear a KN95-certified pollution protection mask, such as the IQAir Mask, to reduce the pollutants they breathe in while they’re walking to school, going between classrooms, or playing outside for long periods. A KN95 or NIOSH N95-compliant mask can prevent up to 95% of particle pollutants from entering their airways.
  • Reduce air pollution: Conserving energy, recycling, driving less, or driving low-polluting vehicles – the choices you make can help reduce air pollution for everyone.

Learning that unclean air can adversely affect your child’s IQ and cognitive development is unsettling. It can be especially worrisome because the threat is invisible.

Fortunately, there is technology to monitor and predict air quality, as well as medical-grade air that you can bring to whatever indoor space your child needs to be.

The number one air cleaning solution for your home.

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