The toxic air is so severe that it may be damaging the brains of an entire generation of Chinese and Indian children (Photo: Mint)
The toxic air is so severe that it may be damaging the brains of an entire generation of Chinese and Indian children (Photo: Mint)

Opinion | Air pollution: PM2.5 really bad for human health, reduces IQ in children

  • In the long term, chronic exposure is correlated with accelerated cognitive decline in old age, including increased risk of dementia, Alzheimer’s, Parkinson’s disease and stroke
  • Children may suffer the most from the baleful effects of toxic air, because the damage done to them can be permanent

Amid all the hubbub about climate change, Americans don't think much about regular old air pollution these days. The coal smoke that once choked cities such as Pittsburgh now exists only in old photographs, and even famously hazy Los Angeles has much less smog. A long string of laws passed during the past 70 years has strengthened government regulation of air quality. As a result, most types of pollution have decreased significantly, especially coarse particulate matter, sulfur dioxide and nitrogen oxides. And Americans’ health has improved in a variety of ways as a result.

But at least one type of dangerous pollution remains fairly common — the fine particulate matter known as PM2.5. These particles, which are less than 4% as wide as a human hair, can include a huge variety of organic chemicals, bits of metal, leftover products from combustion and so on. Concentrations of these particles, which come from vehicles, power plants, fires and various natural events, have gone down by only about 25% since regulations were tightened in 1990:

Like a breathe of fresher air

Meanwhile, a flood of new research shows that this type of pollution does a lot of harm to human health, especially brain function.

Patrick Collison, chief executive officer of online payments provider Stripe Inc., recently posted a roundup of some of the recent startling results. The short-term effects of pollution are easy to measure, because air quality varies from day to day. Chess players, for example, make worse decisions on polluted days. Stock market returns are lower when the air quality is worse in New York City. Politicians’ language is less complex when pollution is higher.

In the long term, chronic exposure to pollution is correlated with accelerated cognitive decline in old age, including increased risk of dementia, Alzheimer’s, Parkinson’s disease and stroke.

Children may suffer the most from the baleful effects of toxic air, because the damage done to them can be permanent. In China, studies have found that exposure to air pollution at birth is associated with reduced cognitive skills later in life. Southern California kids who grew up breathing more polluted air do worse on math and reading tests. Students who switch to a school that’s downwind of a highway (and thus gets more pollution) see their scores decline. One study estimated that an increase in PM2.5 concentration of 5 micrograms per cubic meter — about one half the average level in New York City -- would result in the loss of two IQ points, which is about the amount gained from one or two years of education.

This is a very substantial effect. Even if one believes that math, reading and IQ tests aren’t good measures of cognitive ability, abrupt decreases in these scores indicate that something is hurting children's brains. This is the kind of thing that a functional civilization should be trying to prevent.

Unfortunately, things are getting worse. An analysis by researchers at Carnegie Mellon University found that PM2.5 pollution increased 5.5% between 2016 and 2018, reversing years of decline. Lax enforcement by a presidential administration that has shown great zeal in slashing environmental regulations might be a factor. Climate change and unwise land use patterns might be another; California’s wildfires are huge contributors to fine particulate pollution in that state.

The US government should be taking PM2.5 pollution much more seriously, tightening standards and increasing enforcement for industry, power plants and transportation. The alternative is a populace with degraded health and mental skills.

Fighting air pollution is even more important in China and India, whose rapid coal-powered industrialization has left their cities blanketed in a haze of toxic smog. Beijing’s PM2.5 levels average about 100 micrograms per cubic meter, or about 10 times that of New York City, and regularly exceed twice that amount. India is even worse.

This toxic air is so severe that it may be damaging the brains of an entire generation of Chinese and Indian children. A recent report by the World Bank found that test scores were significantly lower in these countries than in the developed world:

The price China and India pay

Poor countries generally tend to lag rich ones in test scores because of inferior nutrition and education systems. But China and India don’t even measure up to low-income Vietnam. Something is going wrong and air pollution is a good candidate.

For the US, strengthening environmental regulations and cutting fine particulate matter would be a good idea. For China, India and other rapidly industrializing countries it’s an absolute necessity.

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