You want to go outside and get some exercise. As you get together all the things you’ll need, you decide to check the weather. When you do, do you think to look at the air quality? Given that air pollution is becoming more commonplace, it’s probably a good idea. What level of air pollution is safe to exercise in? What damage does it cause if you exercise in polluted air?

Per the World Health Organization (WHO), poor air quality is connected to a higher rate of death from related diseases. The concerning factor is that people living in many parts of the world, especially large cities, are regularly exposed to air pollution levels far beyond the WHO’s recommended limits. There are many things that contribute to air pollution, including power plant emissions, wildfires, motor vehicle traffic, pollen from flowers/trees/shrubbery, wind-blown dust, burning wood, construction and agricultural operations (ex. raising animals and clearing land). These sources together produce three primary types of air pollutants: particulate matter, ozone, and carbon monoxide.

Exposure to any of these can have negative consequences for your health. When exposed to particulate matter, which is inhalable particles at least 10x smaller than the width of the hair on your head, it causes inflammation locally in your lungs and throughout your body. These particles are so small that they can also be deposited directly in your lungs or into your bloodstream, where they end up in your organs. This means that exposure to particulate matter is associated with respiratory and cardiovascular conditions, like heart attacks, stroke, hardening of the arteries, bronchitis, and asthma.

Ozone is also known as smog and is invisible. It irritates your airways, impairs lung function, and lowers your lungs’ defense mechanisms, resulting in airway hyper-responsiveness associated with lung inflammation. Summertime brings prime weather for ozone because levels are often higher when it is hotter. So, a warm summer afternoon would see the highest ozone levels during a 24-hour cycle.

Carbon monoxide actually interferes with your red blood cells’ ability to bind to oxygen, which means that your body isn’t getting enough so it leads to reduced energy production in your cells and increases levels of oxidative stress by providing a pro-oxidative environment.

Inhaling these pollutants in your everyday life obviously isn’t good, and a major concern for most people is whether or not it’s safe to exercise in air pollution. Fears over air pollution were talked about at both the 2008 and 2016 Olympics since levels of particulate matter in the host cities were far above the WHO’s standards. However, most experts felt that this exposure wouldn’t be enough for the two weeks of competition to damage an athlete’s performance. The worry is the effects long-term exposure has on those who regularly exercise in areas with high air pollution.

We do know that air pollution affects everyone differently, so issuing a single statement on how air pollution affects the body during exercise isn’t possible. Some researchers think that exercise may increase a person’s susceptibility to air pollution, which would exacerbate the effects of it, even in healthy individuals. Their determination is the result of the fact that exercising alters your breathing. When you’re moving around more, as is the case when exercising, you have to breathe more frequently, so the volume of polluted air you breathe in is higher. When you’re exercising, you also breathe deeper, so the proportion of very small particles deposited in your airways increases. Another concern is that when you exercise at a high intensity, you switch from breathing through your nose to breathing through your mouth, which means the air bypasses your nose hairs that typically act as a filter.

One study found that long-term exposure to traffic-related pollution might cause to chronic lung issues and asthma. Many individuals who live and exercise in highly polluted areas are experiencing chronic irritation to their lungs, similar to asthmatic symptoms. Exercising in polluted air is an even bigger issue for people with asthma or other lung diseases. This is because they’re more likely to have a reaction to something that would typically be a low-level irritant.

According to the Centers for Disease Control and Prevention (CDC), heart disease is a leading cause of death in the United States. Research has shown that air pollution can contribute to the hardening of the arteries and blood vessel inflammation, which leads to a higher incidence of heart attack and stroke. So, traffic-related air pollution can increase your risk for these to occur and for you to die from them. Certain populations, young children and older adults, are more at risk for feeling the effects of air pollution.

One study found that babies and young children could be exposed to 60% more air pollution than adults due to their height. It doesn’t matter whether they’re walking or in a stroller; they are only a few feet tall, which means they’re nearest the exhaust pipes of vehicles, which have the highest concentration of fumes. The further up you go in height, the less the concentration is. Since a child’s immune system is less developed than an adult’s, they’re more at risk. Air pollution has been linked not only to lung disease, cardiovascular disease, stroke, and dementia in adults but lower cognitive function and a rise in mental illness in children. It also increases the risk of premature birth.

Even for healthy people, at a certain point, inhaling fine particulates does more damage than the benefits of exercise provide, which makes the effort not worth it. It’s estimated that exposure to air pollution is responsible for as many as 4.2 million deaths globally.

However, other researchers feel that regular exercise encourages a physiological response within your body that counteracts the responses exacerbated by air pollution. Two examples of positive implications of exercise are that it reduces systemic inflammation and blood pressure. This has led to the conclusion that for most healthy individuals, the benefits of exercise outweigh the negative effects of air pollution. Physical activity is known to reduce the risk of heart attack. In fact, active commuting, like walking or biking, has been linked to an 11% reduction in the risk of heart attacks or strokes.

A 2015 analysis of information from a study by the University of Copenhagen in Demark showed some interesting results. The study followed 52,061 people, aged 50-65 years, from the two main cities, Aarhus and Copenhagen, for an average of 13 years. From 1993-97, the participants reported on their physical activities, including sports, cycling to/from work, gardening, and walking. The researchers then combined this data with a high-tech street-by-street model of air pollution during this time. After analyzing all of the data, they found that even with exposure to high levels of traffic-related air pollution it didn’t change the beneficial effects of physical activity on mortality. It’s important to note that 5,500 participants died before 2010, but the researchers found that there were about 20% fewer deaths among individuals who exercised than those who didn’t. This was true even for those who lived in the most polluted areas.

For cities larger than the two in the study, like New York, Los Angeles, or Chicago, the effects of pollution are likely to be more noticeable.

Since everyone will have different symptoms in relation to air pollution, it’s essential to listen to your body. Symptoms may include irritated eyes, headaches, increased mucus production in the nose or throat, coughing, and/or difficulty breathing, especially during exercise. If you have chest pain or tightness, sweating, difficulty breathing without exertion, consistent cough/shortness of breath, fluttering in your chest, or lightheadedness, contact your healthcare practitioner.

Health problems associated with air pollution are increased risk of asthma development, worsening of existing asthma or other lung conditions, increased risk of heart attacks/strokes, and increased risk of death from lung cancer and cardiovascular disease. According to the American Lung Association, individuals with lung conditions like asthma or chronic obstructive pulmonary disease (COPD) should avoid exercising outdoors when pollution levels are high since it could trigger an asthma attack.

The most important thing you can do to reduce your risk of being around air pollutants is to monitor air quality. It’s best to look at fine particles (PM2.5), particles smaller than 2.5 micrometers. It’s vital to keep in mind that levels will fluctuate over the course of a day and can vary from block to block. Most communities have a system for finding out local air quality. In order to know where you can locate this information, contact your local/state air pollution control agency, your local hospital, or your doctor. Local radio stations, television stations, and newspapers usually report on air quality.

Some organizations, such as the Environmental Protection Agency (EPA), have websites that provide information about air quality. is a website that provides up-to-date readings of the Air Quality Index (AQI) by ZIP code. The AQI is calculated by measuring the amount of particulate matter in the atmosphere and then ranks the air quality as either very good, good, fair, poor, very poor, or hazardous. The key is to check your local air quality report before going outside to exercise. If you notice that your area has several bad air quality days in a row, you should check overall air quality.

The American Lung Association puts out an annual report, State of the Air, that grades counties and ranks cities based on their ozone and particle pollution over a three-year period.

If you’re tech-savvy, there’s an app, Plume Air Report, that allows for real-time monitoring of air quality in your city. Not only does it have the current air quality, but it can also predict the air quality will be later in the day. The company that created Plume is working on a personal air quality tracker called Flow, which would be a wearable device, very similar to a keychain, that will measure the local air quality in real-time down to street level. Essentially, you’ll be able to map your run, walk, or bike route to avoid air pollution.

Since pollution doesn’t happen just when you’re exercising, be aware of the air you’re breathing before and after you exercise. There are several other considerations regarding avoiding air pollution. One of them is the time of day. Since air quality tends to be the worst from midday throughout the afternoon, especially during the summer months when it’s hotter outside, try exercising in the early morning or late evening. Also, avoid exercising during rush hour.

The next essential thing to consider is the location you choose to exercise in. If at all possible, avoid exercising near roadways. Most experts recommend being at least 350 yards away from major highways because the decline in pollution levels as you move away from a road is exponential. Streets with tall buildings on each side tend to have high concentrations of pollutants because they become trapped. Also, don’t assume that trees automatically mean a cleaner space because tall trees have canopies that are close together and decrease the dispersal of pollution, especially if they’re near tall buildings. This is why lower-level hedges are important because they act as a barrier between road traffic and pedestrians. If you have access to wooded trails, use them since there is plenty of vegetation to filter out air pollution.

If you see the air quality is bad, try changing up your routine with occasional indoor activities, like taking a fitness class, going to your local gym, or running laps on an indoor track. Just keep in mind that heading indoors presents its own challenges with air pollution, such as new carpets, floor wax, or candles/incense in a yoga studio.

If you decide to exercise outdoors on a day when air quality isn’t the best, some things to think about are shortening the length of your exercise time and adjusting the intensity of your workout. This will help to minimize your overall exposure.

Another key item is warming up your lungs by performing effective aerobic activities prior to doing your normal exercise routine. This can help ward off the decline in lung function that people with asthma or exercise-induced bronchoconstriction, a common airway problem in athletes that is different from asthma, often have in polluted air. One example of a good warm-up protocol is 30-second sprints five to seven times at 80 – 90% of your maximum intensity, with 1.5 to 2.5 minutes of rest before starting your workout.

Air pollution impacts your skin because when air quality is poor, the ozone layer that protects you from the sun’s harmful rays can be disrupted, resulting in intensified sun exposure and raising your risk for skin cancer. This means you should slather on sunscreen before heading out the door.

In addition, a growing amount of evidence indicates that what you eat can help lessen the harmful effects of air pollution. A study from researchers at New York University’s School of Medicine looked at data from more than 500,000 people and their adherence to a Mediterranean-style diet alongside their estimated long-term exposure to air pollution. The findings suggest that those who most closely followed the diet are less likely to suffer cardiovascular disease and deaths from all causes, including air pollution.

Some researchers recommend taking antioxidants daily because they help your body fight harmful free radicals that are prevalent in air pollution. If you take antioxidants, like vitamin C or others, they can help neutralize the free radicals in your body. Some foods that are rich in antioxidants are cherries, pomegranates, blueberries, and kale.

Also, it’s essential to know your medical history and how this impacts your ability to exercise if there’s air pollution. It’s vital to watch for symptoms related to air pollution during and after your workout and seek help from medical professionals if you need it. Some individuals wear masks, but the majority of masks leak and get clogged up, which means they don’t really work. In order for them to work, the masks would need to be very tight-fitting, which would make them so uncomfortable that most people wouldn’t wear them.

The fact that air pollution is present in so many urban areas causes many people to choose to exercise indoors or simply skip it altogether because they’re afraid that exercising outdoors will put them at risk for certain health conditions and take years off their life. However, since we know that pollution causes inflammation and exercise reduces it, the long-term benefits of regular exercise outweigh the risks associated with exposure to air pollution. It may reverse some of pollution’s negative effects. This means that you shouldn’t stop exercising, especially outside; just be aware of the air quality before you go out.