As air pollution concerns rise, Google cars have begun to sniff the air to help measure pollution at a neighborhood level.

Max Galka is a data scientist who keeps two air purifiers in his 600-square-foot apartment in New York City.

“A good air purifier costs only a few hundred dollars. So for a health risk as serious as air pollution, I think it makes sense for everyone to have one in the home,” he told Healthline. “I happen to live in the middle of Manhattan, but I would have one no matter where I lived.”

Galka knows the risks of air pollution because he’s studied the data himself. He says if early deaths were counted together, air pollution would be the third leading cause of death in the United States and the world.

“Air pollution is not counted as a cause of death because it is not an illness,” he said. “Rather, it’s a contributing factor to other illnesses.”

Poor air quality has long been linked to lung and heart problems, including coronary artery disease, emphysema, respiratory infections, stroke, and cancer. It also is especially dangerous for pregnant women, as it can contribute to birth defects.

Air pollution can also exacerbate numerous conditions, including asthma, chronic obstructive pulmonary disease (COPD), cardiovascular disease, and diabetes. Children and the elderly are especially sensitive to air pollution.

The World Health Organization says air pollution is the world’s largest environmental health risk, as it killed an estimated 7 million people in 2012 alone. The vast majority of those deaths were due to cardiovascular diseases, namely stroke and ischemic heart disease. Of those, 3.3 million deaths were linked to indoor air pollution.

In the United States, 200 million people — or 62 percent of the population — live in areas where pollutants such as ozone and particulate matter exceed the standards.

“Even within cities, there can be big air quality disparities from neighborhood to neighborhood,” Galka said. “So the next time you are in the market for a home, it’s worth doing some research online to find out about the air quality in the areas you are considering.”

Air quality measurement, something few people consider before heading out the door, is now getting the Google treatment.

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The U.S. Environmental Protection Agency (EPA) is charged with keeping tabs on six common air pollutants: particle pollution, ground-level ozone, carbon monoxide, sulfur oxides, nitrogen oxides, and lead.

The EPA tracks air quality using stationary devices, and the data is made available in different ways. You can view it on an interactive map or on, but only a handful of cities per state are given air quality ratings each day.

Google and Aclima, a San Francisco-based environmental sensor designer, are taking that data down to the street corner. Aclima sensors already test the indoor air quality of 21 of Google’s office buildings.

Just as Google Street View has mapped the surface of the Earth — with the help of camera-equipped camels in the deserts — they’re beginning to sniff out the air they encounter along the way.

The Google camera cars driving around the San Francisco Bay Area are equipped with Aclima sensors to measure pollutants that are harmful to people and/or contribute to climate change.

“If we can see how our cities live and breathe, we can better understand our impact on our environment,” Kim Hunter, director of communications and engagement at Aclima, told Healthline.

In Denver, three Aclima sensor-enhanced Google cars collected 150 million data points. The test drive, conducted in collaboration with the EPA and NASA, aims to bring measurement down to street level, so people can view air conditions at a specific address and time of day.

For example, the mother of a child with asthma could check which parks have the best air quality that day, Hunter said.

The Google cars will continue to measure the San Francisco air through next year, but the recent wildfires in nearby southern Lake County have already been triggering Aclima’s sensors.

“It may not have been obvious stepping out your front door, but it was there,” Melissa Lunden, Ph.D., director of research at Aclima, said. “We really see this platform as a way where hyperlocal air quality is as accepted as the weather.”

If all Google cars were equipped with such sensors, they could fill major holes in air pollution data around the world. Air quality sensors are the priorities of richer countries, leaving large areas of Africa, South America, and Southeast Asia without regular monitoring of their air.

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Of all the pollutants in the air, ground-level ozone and particle pollution pose the greatest threats to humans.

The global health cost of air pollution is estimated at more than $100 billion per year.

Clean air advocate groups such as the Natural Resources Defense Council say until stronger standards to reduce toxic emissions from coal- and fossil fuel-burning industries are implemented, their practices will continue to pollute the air and affect human health.

However, due to increased attention to health effects and tighter restrictions on emissions, both of these have been decreasing steadily since 2002.

Ozone — helpful above the clouds, harmful on the ground — is created by a chemical reaction when oxides of nitrogen (NOx) and volatile organic compounds (VOC) mix in sunlight.

The largest contributors to NOx and VOC are the oil and gas industry, motor vehicle exhaust, gasoline vapors, and chemical solvents, according to the EPA.

Globally, emission rates have been growing by nearly 6 percent each year, but particulate matter levels have not increased at the same rate. Researchers at the World Bank credit advances in technology and global economy structural shifts for the improvements.

Some research has suggested that while particulate matter in the air doesn’t contribute to preterm birth, it does impact babies’ birth weights.

“In rapidly developing countries, such as China, the highest levels of air pollution may be of concern for both outcomes,” concluded a 2014 study in Environmental Health Perspectives.

In areas of high population density, the exposure to air pollution is often greater, with more potential side effects that essentially starve brains of needed oxygen.

Recent research regarding children in Mexico City, the most populous city on Earth, has shown air pollution affects short-term memory and IQ, and may even change metabolites in the brain similar to people with Alzheimer’s disease.

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The people of California could benefit from Google’s turn-by-turn air quality readings, as the state is home to all of America’s top five most polluted metropolitan areas, according to the American Lung Association’s yearly “State of the Air” assessment.

The drought has had a large impact on air quality, but the majority of the pollutants circulating through the California air are due to gas and diesel engines.

With more than 18 million people, the Los Angeles basin area is forever clouded in its trademark brown smog caused by its industry, major ports, and 6.4 million registered vehicles.

While air toxins have lowered by 65 percent since 2008, “the risks are still unacceptably high, especially near sources of toxic emissions such as the ports and transportation corridors,” a report from the South Coast Air Quality Management District concluded.

To no surprise, the Los Angeles area leads in ground ozone pollution, but it’s also fifth in both short- and long-term particle pollution. Leading the board among the worst air quality are Fresno, Madera, Bakersfield, Modesto, and Hanford, all in the Central Valley.

Many California cities are in a perpetual state of reaction, including Spare the Air Days, where burning is illegal and people are encouraged to use public transportation over driving their cars.

Salinas, a small city in the Central Valley, is among the top 25 cities for clean air in the country. It is the only California city on that list.

Still, compared to other cities across the globe, Los Angeles is a breath of fresh air.

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If you think another country’s pollution is its own problem, think again.

In places like China or India, there are cities where you can’t see more than 10 feet in front of your face on a particularly bad day. In places like Mumbai, India, or the small manufacturing city of Linfen, China, breathing the air is about the same as smoking a few packs of cigarettes a day.

While the Earth shares the same air, certain areas are bigger polluters than others, affecting more than just their own air space. This air pollution can cross the Pacific to the West Coast of the United States, and clouds of pollution travel across Europe and Asia regularly.

Researchers at NASA have found that the large amount of air pollution in China is magnifying North Pacific cyclones, which often produce heavy snow and intense cold in the United States.

Only 12 percent of the global urban population lives in cities that meet WHO air quality guidelines, and about half of the urban areas around the world have air pollution at least 2.5 times higher than what WHO recommends.

While many cities across the globe are working to clean up their air with more efficient and sustainable energy, as well as an emphasis on public transportation and increased use of bicycles, developing nations don’t have the resources to make those changes as quickly.