How is air quality measured at home?

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According to the Environmental Protection Agency (EPA) (opens in new tab), we spend around 90% of our time indoors – in the home, the office or in an educational setting, Yet, how much consideration do we give to the air we breathe inside – and to how air quality is measured at home?

Poor indoor air quality is the biggest environmental risk to health – responsible for more than 6.5 million premature deaths globally per year – in findings by the World Health Organization (opens in new tab). The coronavirus pandemic has highlighted the importance of clean air and improved ventilation, and the measuring of indoor air quality.

We look at how you can keep an eye on the air quality in your home and whether humidifiers – devices that add moisture to the air – can improve the quality of your air. Check out our guide to the best humidifiers for the lowdown on these devices.

Air quality at home: What you need to know

The quality of the air outside has been of concern for many years, but what about air quality indoors? The concentration of pollutants in the air inside can be between two and five times more than the air outside, says the EPA (opens in new tab), meaning the health risks may be greater indoors. But why?

Pollutants, such as carbon dioxide, carbon monoxide, nitrogen dioxide and low-level ozone, can enter your home from outside, but many things found within the home will have a cumulative and detrimental effect on your air quality.

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The most harmful pollutant is small particulate matter resulting from the combustion of solid fuels used in cooking and heating. Other sources include soot, smoke, dust, dirt, mold, tobacco products, cleaning products and cosmetics, and central heating and cooling systems.

But how do you know if you have poor air quality within your home? Immediate, yet short-term effects include irritation of your eyes, nose and throat, headaches, dizziness and fatigue, says the EPA (opens in new tab). Repeated or prolonged exposure may result in long-term health conditions, such as chronic and acute respiratory diseases, heart disease and cancer.

Reducing or eliminating the source of pollution can restore the air quality in your home. Opening doors and windows improves ventilation and allows the air to circulate naturally, diluting emissions and literally blowing the pollutants away. Mechanical ventilation, using outdoor vented fans, for example, can remove air from a single room, while air handling systems replace indoor air with filtered outside air at strategic points in the home.

You could also use an air cleaner, the best air purifier, or a humidifier to increase moisture levels within the home to keep irritants like mold and polluting particles at bay.

Can humidifiers help with air quality at home?

Humidifiers are electronic devices that increase the humidity or level of moisture in the air, usually in a single room within your home. The optimum humidity is between 30%-50%, according to the Centers for Disease Control and Prevention (opens in new tab), but humidity levels can drop to as low as 10% in winter, when cold outside air is heated indoors and becomes dry.

“Humidifiers are particularly helpful in cold climates, where indoor humidity may be too low in winter,” says Eric Schiff, a physics professor and air quality expert from Syracuse University. “Bedroom humidifiers used with a closed bedroom door can improve air quality inexpensively.”

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Humidifiers come in a number of forms, but all have the same basic principle: add more moisture to air. There are warm-mist humidifiers, like a vaporizer that heats water to steam; cold-mist humidifiers like the evaporative humidifier that use a fan to blow air over a wet wick; the impeller, which creates a mist using a rotating disc, and an ultrasonic humidifier that uses a vibrating nebulizer to emit water.

Humidifiers improve the air quality in your home by increasing the amount of moisture in the air. This can alleviate a number of health-related issues, including dermatitis (opens in new tab), a condition where the skin can become dry, itchy and flaky. Increasing humidity can prevent the mucous membranes in your nose and throat from drying out, and prevent dry coughs, and stop dry-eye syndrome, which is often caused by cold, dry and dusty environments.

We should be careful to avoid excessive humidity, too, says Schiff. “Humidifiers should mainly be run to increase relative humidity to 40% when possible. Lower levels increase a person’s susceptibility to disease. Higher levels lead to growth of organisms, like mold, that are unhealthful.”

Steps to measure air quality at home

You can measure the air quality in your home using an always-on electronic monitor that consistently tests and reports the levels of pollutants and humidity via an in-built display panel, or linked to a smartphone. Some also track temperature, carbon monoxide and carbon dioxide levels to give an overall real-time snapshot of the air quality at any moment.

“Many inexpensive indoor thermometers also measure relative humidity. These are recommended,” says Schiff. “More advanced and expensive devices also measure small particles and volatile organic compounds in the air. These can be helpful when there are health issues in a family, or when living in places with significant air pollution.”

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Carbon dioxide monitors can identify poor areas of ventilation and are increasingly being employed in schools and work environments to help reduce the spread of coronavirus, says the Health and Safety Executive (opens in new tab). COVID-19 spreads easily indoors and increased ventilation with outside air or by use of air purifiers can counter the spread, says Schiff: “These measures are important in public spaces like stores, restaurants, and schools.”

It’s also worth getting a carbon monoxide monitor to test for the tasteless, odorless and colorless gas, particularly if you have a gas furnace or gas-burning stove. The gas is a byproduct of fuel combustion, and lighter than air, so monitors should be placed high up, near the ceilings.

The air quality within your home, or any enclosed space, may represent a significant health risk, particularly during the coronavirus pandemic. You can measure your air quality using an in-home monitor that gives you real-time readings and then take steps to improve the quality of the air, either by improving ventilation, reducing pollutants or increasing humidity with a humidifier if the air is too dry.

Kerry is a freelance writer and editor, specializing in science and health-related topics. Her work has appeared in many scientific and medical magazines and websites, including Forward, Patient, NetDoctor, YourWeather, the AZO portfolio, and NS Media titles.

Kerry’s articles cover a wide range of topics including astronomy, nanotechnology, physics, medical devices, pharmaceuticals and mental health, but she has a particular interest in environmental science, cleantech and climate change. 

​​​Kerry is NCTJ trained, and has a degree Natural Sciences from the University of Bath where she studied a range of topics, including chemistry, biology, and environmental sciences.