Studies now 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?
Intellectual Quotient (IQ) is an imperfect predictor of many outcomes, such as academic performance and lifetime earning potential. Nevertheless, 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 benchmarking tool.
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 surrounding teens’ homes, their performance IQ score dropped one point.
In one study, researchers found that, for every increase of 2.5 micrograms per cubic meter (µg/m³) of fine-particle pollution (PM2.5) surrounding the teens’ homes, their performance IQ score dropped one point. It’s important to note that performance IQ measures reasoning and problem-solving abilities, which is a different measurement than verbal IQ.
“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 foetus and young child are especially vulnerable to neurotoxicants, 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 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. 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.
Poor air quality exposure and student GPA (Grade Point Average)
The relationship between children’s health and academic achievement have consistently found that poorer health status is associated with worse academic achievement outcomes. When children are unhealthy, they may have more difficulty learning than their healthy counterparts and have poorer academic achievement outcomes.
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.
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 fourth and fifth graders 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.
Air quality and standardized test scores
Multiple studies have identified a link between air quality and performance on standardized tests. 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.
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.
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.
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.
A separate study of fifth-grade 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.
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:
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.