Outdoor Air Pollution

Throughout the world, clean air is a precious resource that can be hard to come by. You don’t need to live in a metropolis to be breathing in toxic fumes every day. All you need to do is live in a city or near a major road. While it would be nice if us humans were unaffected by pollution, the fact is, we are.

Pollution isn’t often what people think about when evaluating where to live. I hadn’t considered it at all before getting sick. After all, America has relatively little pollution, right? By the time I realized how much it was affecting me, many of my body’s core functions had shut down. My digestive system, thyroid gland, menstrual cycle, thinking, and memory were all shot. I was chronically exhausted and experienced severe anxiety. As soon as I moved away from the polluted city I lived in, and removed indoor air pollution sources, all of these symptoms abated and my health improved dramatically.

Health Impacts

Poor air quality has long been associated with increasing the risk of asthma and cardiovascular diseases, such as heart disease and stroke​1​. Increasingly, studies are linking air pollution to a myriad of other ailments, including:

  • Auto-immune diseases​2​ such as multiple sclerosis​3,4​ and inflammatory bowel disease​5​
  • Mental health: depression, anxiety, cognitive impairment​6,7​
  • Migraines​8​
  • Reproductive disorders such as decreased fertility​1​
  • Cancer: especially lung cancer and childhood leukemia​1,9​
  • Obesity​9​
  • Death​1,9,10​

Additionally, those with pre-existing health issues are more vulnerable to the effects of air pollution​2​. Keep in mind that many of these conditions are linked to the increased stress​2,3,6,7,9​ pollution puts on the body. In conjunction with other stressors, health can deteriorate faster.

For me personally, air pollution causes immediate symptoms such as brain fog, anxiety, fatigue, nausea, and occasionally vertigo or headaches. In the long term, it was one of the underlying causes for my severe gastrointestinal dysfunction.

Pollution levels in your area

Per county/city

While America has clean air on average, the cities, where the majority of people live, are often filled with noxious gases. The following map shows how much pollution, in tons per square mile, is generated across the United States in just one year!

Pollution generated per year in tons per square mile
Check out the interactive map created by the EPA to see how your region compares!
National Emissions Inventory (NEI) 2014 report

Some regions are much worse than others, as the map above shows. The top 50 pollution generating locales are shown in the table below:

Top 50 Air Pollution Generating Counties/Cities in the U.S.

Compiled from data available in the National Emissions Inventory (NEI) 2014 report
State County Yearly Air Pollutants (Tons/SqMi)
New York New York 5866.565901
New York Kings 1394.151366
New York Queens 1209.173434
New York Bronx 1170.324672
Massachusetts Suffolk 1004.228225
District Of Columbia District of Columbia 943.4711786
New Jersey Hudson 892.9124233
Virginia Falls Church city 863.9461447
Virginia Arlington 826.8086647
California San Francisco 821.887115
Virginia Alexandria city 770.48706
Virginia Norfolk city 739.2234925
Pennsylvania Philadelphia 687.7453213
Colorado Denver 645.5298784
Missouri St. Louis city 592.0719799
New York Richmond 591.3341689
Illinois Cook 579.0453929
Virginia Fairfax city 574.1311223
Maryland Baltimore city 566.0260094
New York Nassau 540.9121895
Florida Pinellas 539.404278
Virginia Charlottesville city 534.7223682
Minnesota Ramsey 527.4232768
New Jersey Union 520.3394721
Virginia Richmond city 512.3625853
Virginia Fredericksburg city 510.0225598
Virginia Manassas Park city 508.6543262
New Jersey Essex 506.6792439
Indiana Marion 462.6676787
Illinois DuPage 457.8029848
New Jersey Bergen 457.4688103
Virginia Winchester city 417.1973095
Wisconsin Milwaukee 410.6978581
Virginia Hampton city 410.064417
Virginia Harrisonburg city 395.8870008
Ohio Cuyahoga 395.2031247
Virginia Newport News city 380.1198999
Missouri St. Louis 371.8517794
Michigan Wayne 370.4821575
Minnesota Hennepin 365.45601
Virginia Roanoke city 359.8376371
Louisiana Orleans 354.1427481
Georgia DeKalb 349.371343
Virginia Portsmouth city 348.0114254
Virginia Manassas city 338.2847948
Virginia Colonial Heights city 338.0653114
Texas Dallas 334.6709785
Kentucky Jefferson 331.3842094
Georgia Cobb 324.7041215

The values shown in the table and map are averaged across an entire region. Sometimes this can give misleading numbers. For example, King County Washington is home to Seattle and its surrounding metropolitan area. However, this county is huge and also contains an expansive amount of countryside. Out in the country, pollution is extremely low, while in the city it’s quite high. Therefore, averaging the pollution of the county as a whole gives a false impression. In reality the major cities contain higher levels than this average while the countryside contains lower levels.

Immediate surroundings

Knowing how bad your general area is just gives a baseline. Pollution levels can vary a lot within a county or a city.

Cities and roads

Automotive traffic is one of the leading sources of air pollution within cities. The further away you live from a major road, the cleaner the air gets. Pollution levels are highest within 500 feet of a major road and can take over a quarter mile to dissipate​11​. It’s no secret that tons of fumes and particulates are produced by major traffic sources. If you’ve ever seen snow banks near a busy road in winter, you know how black they get from all the nearby exhaust. It’s not what you want to live next to and breath in every day!

Trees and plants

Living walls of greenery help reduce how far pollution spreads from its source. Vegetation works best when it is somewhat dense, wide, and tall. One recommendation is that these barriers be at least 5 meters (16 feet) wide​11​. You can think of an effective green barrier like a sponge or a carbon filter. Particulates stick to the vegetation as they filter through. Without filtration, the pollution will slowly settle and dissipate, but will spread much further from their source.

Sources of pollution


Vehicle emissions are by far the biggest contributor to city pollution. As cities grow, more people drive, commutes lengthen, and rush hour traffic worsens. All of this adds to increasingly high quantities of exhaust filling the air. The small silver lining is that more fuel efficient cars are now being driven, somewhat offsetting the increased traffic load.

Airports are an often overlooked hub of pollutants. Planes flying daily in and out generate a lot of exhaust! Other forms of transportation such as trains, boats and ships, tractors, and recreational vehicles such as snow mobiles, 4-wheelers, and dirt bikes also contribute to air pollution.


Fortunately, in our modern age, the harmful emissions from factories and other industries have been dramatically reduced from times past. Strict environmental standards have aided us in reducing what was traditionally a major contributor to city smog. Factories still release contaminants, even if in much lower quantities than in the past, so industrial areas will have additional pollution from this source.



Forest fires dramatically increase the pollution levels while they rage. Summer fires on the West Coast are particularly large and problematic, typically a yearly concern. Controlled burns also add to smoke in the air, but at a far reduced rate than the forest fires they are used to help prevent.

Burning wood for fuel

A seasonal hazard for areas in the North is wood burned as fuel during the cold winter months. Though wood is cheap, it generates a lot of pollution. Not only does it add to the particulate level in the general area, most smoke is released straight into the indoor air of homes that use it. If you burn wood during the winter, consider the high cost not only to others, but to yourself!

Burning refuse piles

While this is a convenient way to remove debris from your property, it too adds to the pollution levels. Instead of burning, consider composting or hauling refuse to a facility that will handle it responsibly.


These are another seasonal hazard during the winter months. An inversion occurs when cold air sinks into a region and warm air rises above it. The cold air traps pollutants in it. While an inversion is in effect, pollution builds up day by day, often reaching extremely unhealthy levels​10​. Certain locations are more commonly affected than others, especially cities that lie in valleys. For these residents, inversions may be a common occurrence during winter. Signs that one is in effect include low lying regions experiencing much lower temperatures than the surrounding higher elevations and smog.

Conventional farms

Conventional farms, farms that don’t practice organic methods, use a wide variety of dangerous chemicals. Crops are sprayed with harmful pesticides which then disperse into the surrounding air​12​. While this isn’t a pollutant that generally affects city dwellers, except by eating said products, it’s something to be aware of if you live in or near a farming community.

Other air pollutants come from intensive animal rearing practices. Thousands of animals penned in close quarters generate a lot of waste, so much that it can’t be easily absorbed into the environment. Instead, clouds of ammonia, a well known toxin, collect around such establishments. On the up side, as ammonia is highly pungent and caustic, it’s unlikely you would be exposed without knowing it.


It’s best to avoid air pollution as much as possible by living away from big cities and busy roads. For those that don’t wish to abandon city life, there are some ways to lessen the severity of the surrounding air, though the following improvements will only help so much.

Air filtration units

For indoor spaces, you can purchase an air filtration unit that can filter out VOCs, Volatile Organic Compounds. It’s important to note that a HEPA filter alone will only trap small particles; it will not cleanse the air of toxic fumes such as those given off by car exhaust. Air filters help most in bedrooms, offices, and other rooms you spend a lot of time in. Cleaner air promotes deeper sleep, and getting a good nights sleep lowers overall stress. So, if you have to pick one room, pick the bedroom.

Air filtration face masks

These aren’t the most fashionable items, but if you are sensitive to air pollution, they can be a life-saver. It’s impossible to avoid pollution all the time. Sometimes you need to head into high-traffic areas or visit family in the big city. Wearing a mask can be the difference between normalcy and feeling like you’re dying.

A good mask will have both HEPA and VOC filtration. If you plan to wear a mask a lot, I recommend getting one with replaceable filters so you can continue to use it for years.

The mask I currently use is made by Respro. It’s designed for people who wear a mask while engaging in outdoor activities, like biking or running, in polluted or dusty areas. It has a tight seal around the face, good airflow, and is rigid enough so it doesn’t get sucked in when you inhale. Please note, the sizing runs small, so order a size up from what their guidelines say! A size medium fits me perfectly and I’m a petite lady.

The first mask I tried was a Cambridge mask, which did a pretty good job filtering the air, although there were a some downsides for me. First, it didn’t provide an air-tight seal around my face. Second, if I used it while biking, moisture built up and quickly fogged up my glasses. Heavy breathing also caused it to get sucked to my face which then made breathing more difficult.

Avoid exercising in polluted areas

While exercise makes a good addition to a healthy routine, in polluted areas the deep breathing from moderate to heavy exertion sucks fumes and particulates deep into the lungs, and increases overall exposure to toxins. It’s much healthier to travel for a weekly hike or bike ride in the forest than to jog daily through the city. If you must exercise outdoors in the city, try to pick routes away from major roads. When traversing heavily polluted areas, I highly advise wearing a good air mask.

Reducing pollution

No longer is the majority of pollution caused by factories and industry. We as individuals are to blame, most notably, by driving vehicles every day. The best solution for reducing emissions is to drive less!

Reduce vehicle emissions

  • Walk or bike – The best option if you live close to where you need to go. This is an easy way to get in some exercise too!
  • Mass transit – If you can, take a bus, train, or metro to where you need to go
  • Carpool
  • Don’t leave your car idling – Unless you have an electric or hybrid vehicle, idling just pumps exhaust into the air for no reason
  • Avoid rush hour – Stop-and-go traffic wastes gas and adds more air pollution per distance traveled
  • Use a more fuel efficient vehicle
    • Electric – The best choice since they add no pollution to the region you drive in
    • Plug-in electric – These vehicles can run on electricity for short distances, anywhere from 10-50 miles​13​ before switching to a standard combustion engine. This means they emit no pollution during short city drives.
    • Hybrid – Using a combination of a combustion engine and chargeable battery, these vehicles are much more fuel efficient. The battery is what powers the car, the gas engine is what charges the battery. In a hybrid, idling and driving downhill burn no fuel because no power is needed from the battery. By contrast, a vehicle running only using a combustion engine must burn gas constantly to keep the engine running, even if stopped at a light. In a hybrid, since gas is only used to charge the battery, the gas engine is started and runs until the battery is recharged, then the engine is killed again.

Reduce smoke

  • Use gas or electric heating instead of wood or coal
  • Don’t burn debris piles
  • Be aware of fire bans. Don’t be the person that starts a forest fire

Discourage pesticide use

Buy organic or local products that were farmed without the use of toxic pesticides, insecticides, or herbicides

Every bit helps

Together we can all reduce how much we add to air pollution. You may not see a lot of personal gain by changing your habits, but it all adds up! For more tips on how to lower your emmisions, check out the EPA article on What You Can Do to Reduce Pollution from Vehicles and Engines.

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    Holgate S, Agius R, Ashton J, et al. Every Breath We Take: The Lifelong Impact of Air Pollution. Royal College of Physicians. Report of a working party. London: RCP; 2016:123. Accessed June 2, 2019.
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    Transport and public health . European Environment Agency. Published September 30, 2016. Accessed June 4, 2019.
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    Baldauf R, McPherson G, Wheaton L, et al. Integrating Vegetation and Green Infrastructure into Sustainable Transportation Planning. TR News. 2013;(288):14-18.
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    FAQ. Plug-in Hybrid & Electric Vehicle Research Center. Accessed June 5, 2019.

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