Can clean air increase child IQ?

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 do not 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. Clean air can prevent the lowering of a child’s IQ by the avoiding detrimental effects of breathing unclean air, but can clean air actually increase child IQ?

Air quality and child IQ test scores

Living in a polluted area as a preteen 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 dust 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). It’s important to note that performance IQ measures reasoning and problem-solving abilities, which is a different measurement than verbal IQ(3).

“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 one statistician involved in 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 children are especially vulnerable to neuro-toxic substances, such as polycyclic aromatic hydrocarbons (PAHs) that are released during the combustion of fossil fuel and other organic material. Two long-term studies are revealing that common air pollutants inhaled 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. 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(4).

Poor air quality exposure and student GPA

The relationship between children’s health and academic achievement have consistently found that poorer health status is associated with worse academic achievement outcomes(5). When children are unhealthy, they may have more difficulty learning than their healthy counterparts and have poorer academic achievement outcomes(6).

It is difficult to separate the many factors that influence academic achievement. However, 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(7).

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

Another study found that year four and five students who are exposed to toxic air pollutants at home are more likely to have lower GPAs. Additionally, children who were exposed to high levels of emissions from cars, trucks and buses on roads and highways had significantly lower GPAs, even when accounting for other factors known to influence school performance. Furthermore, higher school-based hazardous air pollution (HAP) levels are found to be associated with lower individual-level grade point averages.

These findings indicate the need for regulations on school siting and adjacent land uses to protect children's health(8).

Air quality and standardized test scores

Multiple studies have identified a link between air quality and performance on standardized tests(9). 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(10).

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. There is also mounting evidence that poor Indoor Air Quality 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 l/s 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(11).

There was 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(12).

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(13).

A separate study of year five school children concluded that every increase of 0.06 cubic meters per minute (m3/min) in ventilation was associated with a 2.9% increase in students passing a standardized math test(14).

What you can do

We can each play an important role by 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:

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 using the HealthPro or CleanZone air purification systems.

Monitor your Indoor Air Quality.

AirVisual Pro by IQAir lets you monitor pollutants in your indoor and outdoor air so that you know exactly 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 Series room air purifier.

Use a high-powered personal air purifier, such as the IQAir Atem, where your child studies. Students can ensure they are breathing clean air, no matter where they are.

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 bring medical-grade air to whatever indoor space your child needs to be.


[1] Kaufman S. (2014). What do IQ tests test?: Interview with Psychologist W. Joel Schneider

[2] Boyd-Barrett C. (2018). Teen exposure to air pollution could reduce IQ levels long term

[3] Hawkins K et al. (2002). Verbal IQ–performance IQ differentials in traumatic brain injury samples DOI: 10.1093/arclin/17.1.49

[4] Cone M et al. (2010). Urban air pollutants can damage IQs before baby's first breath

[5] Le F et al. (2013) Effects of child and adolescent health on educational progress DOI: 10.1016/j.socscimed.2012.10.005

[6] Basch C. (2011). Healthier students are better learners: a missing link in school reforms to close the achievement gap DOI: 10.1111/j.1746-1561.2011.00632.x

[7] Clark-Reyna S et al. (2015). Residential exposure to air toxics is linked to lower grade point averages among school children in El Paso, Texas, USA DOI: 10.1007/s11111-015-0241-8

[8] Grineski S. (2016). School-based exposure to hazardous air pollutants and grade point average: A multi-level study DOI: 10.1016/j.envres.2016.02.004

[9] Stafford T.(2015). Indoor air quality and academic performance DOI: 10.1016/j.jeem.2014.11.002

[10] Clark-Reyna S et al. (2016). Health status and residential exposure to air toxics: What are the effects on children's academic achievement? DOI: 10.1097/FCH.0000000000000112

[11] Haverinen-Shaughnessy U et al. (2011). Association between substandard classroom ventilation rates and students' academic achievement DOI: 10.1111/j.1600-0668.2010.00686.x

[12] Haverinen-Shaughnessy U et al. (2015). Effects of classroom ventilation rate and temperature on students' test scores DOI: 10.1371/journal.pone.0136165

[13] Shaughnessy R et al. (2006). A preliminary study on the association between ventilation rates in classrooms and student performance. Indoor Air 16(6): 465-468.

[14] Cone M et al. (2010). Urban air pollutants can damage IQs before baby's first breath

Air Quality Life is brought to you by The IQAir Group and Filtercorp Health, the world’s leading innovator of Indoor Air Quality solutions since 1963. This online publication is designed to educate and inform the public about the latest research and news affecting indoor and outdoor air quality.

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