In a study published in The Lancet,1 researchers called air pollution the “largest environmental cause of disease and premature death in the world today.” More than 9 million premature deaths were caused by air pollution in 2015, nearly 16 percent of deaths worldwide. This was three times more deaths than attributed to tuberculosis, malaria and AIDS combined.

According to the World Health Organization (WHO), 92 percent of the world breathe polluted air,2 and air pollution is a major contributor to lung and respiratory infections, heart disease and cancer. However, what many fail to consider is indoor air pollution may actually be as dangerous as outdoor air pollution.

For instance, indoor air pollution of volatile organic compounds (VOCs) linked to neurological symptoms are two to five times higher than outside.3 Sociological studies suggest Americans spend nearly 92 percent of their day inside,4 meaning your indoor air quality is critical to your long-term health.

The most dangerous air pollution is fine particulate matter, referring to particles smaller than 2.5 micrometers in diameter (PM2.5). These particles are small enough to pass through lung tissue and enter your bloodstream, triggering chronic inflammation and disease. Recent research finds reducing indoor pollution may result in improving your blood pressure.5

Reducing Air Pollution Again Tied to Improvements in Heart Health

The researchers sought to answer whether portable air filtration systems could reduce exposure to fine particulate matter and therefore affect blood pressure in elderly adults. The study was conducted in a low-income senior residential building in Detroit, Michigan, using 40 nonsmoking adults.6

They measured PM2.5 exposure and cardiovascular factors, including blood pressure and heart rate variability, on a daily basis. Previous studies7 have demonstrated even short-term exposure is linked with an increased risk of cardiovascular conditions. Long-term exposure amplifies the risk and increases the potential development of chronic heart and metabolic conditions.

The WHO8 guidelines recommend an average exposure of 10 micrograms per cubic meter of air (ug/m3) as an upper limit. Prior to installation of the air filters, the average exposure for the seniors was 15.5 ug/m3. The researchers measured the residents’ blood pressures after using three different types of portable air filters for three days each.

A low efficiency filter reduced PM2.5 concentration to 10.9 ug/m3; a high-efficiency particulate air (HEPA) filter reduced it to 7.4 ug/m3. The third control filter did not clean the air. Using either the low or high efficiency air filter, researchers found blood pressure levels in those who suffer from hypertension improved by an amount similar to what could be achieved with lifestyle changes.9

Although the study was too small to detect meaningful differences in blood pressure based on the type of air filtration, and didn't track individuals to determine if they developed or died from cardiovascular diseases, participants did enjoy a reduction in blood pressure. Lead study author Masako Morishita, of Michigan State University in East Lansing, commented:10

“A simple intervention using inexpensive indoor air filtration units can help to lower both PM2.5 exposures and blood pressure levels. Since hypertension is the leading risk factor for death worldwide, we believe much larger trials are warranted to test whether air filtration units can play an important role in helping to prevent cardiovascular diseases worldwide.”

How Blood Pressure Affects Your Heart Health

The featured study confirms previous results11 from Canadian researchers studying healthy adults living in British Columbia. HEPA filters reduced the amount of airborne particulates and participants experienced improvements in blood vessel health and reductions in blood markers associated with an increased risk of heart disease.

Blood pressure measures pressure of blood against your blood vessels as it moves through your body.12 When pressure is too high, it places strain on your arteries and heart, leading to an increased risk of heart attacks and strokes. High blood pressure (hypertension) does not usually have clinical symptoms, so the only way to tell is to have your blood pressure measured.

Each measurement consists of two numbers, one on the top and one on the bottom. The top number is your systolic blood pressure or the highest level pressure reached as your heart beats. The bottom number is your diastolic pressure, which measures the lowest level pressure as your heart relaxes.

Hypertension is an important risk factor in cardiovascular disease and mortality. A report from Global Burden of Disease focuses on the heavy toll it has on health in all regions of the world.13 The rise in pressure changes the structure of arteries, increasing your risk of stroke, heart disease and kidney failure.

The WHO14 estimates 51 percent of stroke and 45 percent of ischemic heart disease deaths are attributed to high systolic blood pressure. In 2013, hypertension was the No. 1 individual risk factor associated with death worldwide, contributing to 10.4 million deaths.15

It also appears to be distributed relatively evenly throughout the world as the WHO reports16 rates between 30 percent to 45 percent in men and women from low-, middle- and high-income countries.

In the U.S., the Centers for Disease Control and Prevention (CDC)17 reports southern states have the highest percentage of adults with high blood pressure, but acknowledges these self-reported numbers are likely underreported as nearly 20 percent of adults are unaware they have the condition.

Indoor and Outdoor Air Pollution Impacts More Than Your Blood Pressure

Air pollution affects your cardiovascular system in more ways than raising your blood pressure. In one study,18 researchers found small particulate matter has an affinity for accumulating in damaged or inflamed areas of the vascular system. This suggests microscopic particles have the ability to access your bloodstream, increasing inflammation in susceptible areas of your arterial system.

Another study19 evaluated damage from air pollution emitted from diesel burning engines and found they accumulate in your nervous system, causing damage to your brain tissue. After only 30 minutes of exposure to diesel fumes, data demonstrated a significant increase in brain activity, corresponding to a stress response.

Although several long-term effects of exposure to poor indoor air quality are just being further explored through intensive research to document health effects, some known health challenges include:20,21

Decreased lung function

Asthma and bronchitis

Decreased cognitive function22

Diabetes

Emphysema

Lung cancer

Shortened life span

High blood pressure

Pneumonia

Heart attack

Stroke

Depression

Reducing Your Exposure to Air Pollutants

You may be surprised by the number of chemicals in your home leaching from building materials, DIY projects, personal care products and flame retardant chemicals added to home furnishings.

Although it is impossible to completely avoid inhaling any pollution, there are steps you may consider to significantly reduce your exposure and the impact it has on your health. For more suggestions on how to keep the air in your home healthy, see my previous article, “Indoor Air Quality: The Invisible Epidemic Causing Headaches, Fatigue and Depression.”

• What you eat may buffer the effects of pollution — Strive to eat a diet of whole foods, rich in anti-inflammatory vegetables and healthy fats. Among the most important include eating omega-3 fats, broccoli sprouts, and foods rich in vitamins B, C and E. For more information about how they reduce the effects of pollution see my previous article, “Air Pollution is Becoming More Dangerous.”

• Air purification — Attention to your indoor air quality is important and adding a quality purifier is a good start. Commercially purchased filters may lower the amount of C-reactive protein and other measurements of inflammation.23 However, no one filter can remove all pollutants and it’s important to ensure the filter you use is rated for your room size.

Photocatalytic oxidation (PCO) is one of the best technologies available today. Rather than filtering the air, PCO actually acts as an air purifier, cleaning the air using ultraviolet light. Unlike filters, which simply trap pollutants, PCO transforms the pollutants into nontoxic substances.

• Open windows and get some plants — One of the simplest ways to lower pollution in your home is to open windows at opposite ends of your home for at least 15 minutes each day to create cross-ventilation. Since most new homes are airtight for energy efficiency, air pollutants may build more quickly. Consider cracking a window at night and installing an attic fan to bring fresh air into your home.

Plants also remove pollutants by absorbing them through their leaves and roots, in much the same way they clean the outdoor air from the pollution given off by manufacturing plants, cars and heating systems.

Data also demonstrates house plants may help improve your attention and productivity, reduce anxiety, improve accuracy and memory retention and reduce sick days. For a list of indoor plants to help clean your air see my previous article, "12 Healthy Houseplants That Improve Your Indoor Air Quality."

• Roll up your car windows in heavy traffic — The consistent recommendation from studies listed in my previous article, “Indoor Pollution in Your Car,” is to roll up your windows and use the recirculate setting on your car when you’re in heavy traffic or if you’re stopping frequently at red lights.24

While this is important, in newer and more airtight cars may this may lead to an increased buildup of carbon dioxide causing the car to feel “stuffy” when two or more people are breathing the same air for an extended period of time.

Too much carbon dioxide may increase the potential of experiencing drowsiness, fatigue, confusion, headache and sleepiness.25 Prevent this by pulling in outdoor air for two minutes every 10 to 15 minutes.