Dyson Connected Purifier Data: The U.S. experienced indoor air quality worse than outdoor for three quarters of 2022

• Two-thirds of countries experienced higher annual average indoor PM2.5 levels compared to outdoor in 2022². The U.S. saw average annual indoor PM2.5 levels 9% higher than outdoor PM2.5.
• All countries’ monthly average indoor PM2.5 level exceeded the World Health Organization’s (WHO) long-term exposure guidance for at least 6 months in the year³. Among others, the U.S. exceeded WHO guidance every month in the year.
• Winter was the most polluted season in all geographies, with January being the most polluted month in the U.S.
• In an average 24h period, the most polluted time in the U.S. (PM2.5) fell between 6 p.m. and midnight, coinciding with times when people are usually in their homes, and therefore exposed to these higher pollutant levels.Only 8% of Dyson purifier owners globally are using their machines in Auto mode to respond to these air quality challenges.

CHICAGO, January 11, 2024 – Today, Dyson unveils the results of its first Global Connected Air Quality Data project. The project analyzes indoor air quality information collected by more than 2.5 million Dyson purifiers from 2022 to 2023 to landscape air quality in real homes across the world, to a high degree of granularity, breaking down pollution into gas and particle pollutants, and profiling trends over days, months, seasons and the full year. The data comes from Dyson purifiers connected to the MyDyson app; the volume of data exceeds half a trillion data points and paints a precise picture of indoor air quality in cities and countries globally to he.lp build understanding and awareness of indoor air pollution.

From a wealth of data, this project focuses on two types of pollutant – PM2.5, and Volatile Organic Compounds (VOCs). PM2.5 refers to particles as small as 2.5 microns in diameter, 1/25th the diameter of a typical human hair. These particles are invisible to the naked eye, can be inhaled and are an area of increasing scientific and health research. Sources include combustion, – wood burners, or gas cooking and heating – pet dander, ash and dust. VOCs are gas pollutants including Benzene and Formaldehyde which can be emitted from activities like cleaning or gas cooking as well as from products including deodorants and body sprays, candles, furniture and furnishings.

“Our connected air quality data allows us insight into the real problem of indoor air pollution in homes across the world. This gives us a direct understanding of the challenges Dyson purifiers face in real environments and the knowledge to engineer ever-better machines to tackle those challenges. But the data we capture isn’t just an engineering tool – on an individual basis, this data is shared back through the MyDyson app in real-time and via monthly reports, to help our owners improve their air quality understanding.” – Matt Jennings, Engineering Director for Environmental Care

“We all think of air pollution as being an outdoor or roadside problem. Indoor air pollution research is growing, but continues to be underdeveloped. Dyson's findings give us a valuable insight into the real pollution levels in homes across the world, helping us to understand the patterns of pollution daily, monthly and seasonally. The Dyson data is an incredibly powerful education tool and the opportunities for positive impact are boundless – understanding the pollution around us is the first step to reducing our pollution exposure.” – Professor Hugh Montgomery, Chair of Intensive Care Medicine at University College London, and Chairperson of Dyson’s Scientific Advisory Board 

Nearly all homes experienced indoor air quality worse than outdoor

All but four countries studied exceeded outdoor PM2.5 levels for six months or more, including the U.S. where indoor levels exceeded outdoor PM2.5 monthly averages for nine months of 2022. In February, most countries experienced the largest gap between indoor PM2.5 as compared to outdoor, where indoor exceeds outdoor levels. However, the U.S. registered the highest indoor PM2.5 level compared to outdoor in March – which was 30% higher than outdoor. 20 out of 31 countries studied saw an annual average indoor air quality that exceeds the outdoor air quality, when considering PM2.5.

Winter sees highest pollution levels

During winter, we spend an increasing amount of time in our homes. Throughout the year, we spend 90% of our time indoors – at home, work, or for leisure. Dyson purifier data showed that the winter period was the most polluted season globally. Colder weather means we seal our homes more, keeping windows shut and possibly heating with combustion, like gas heating, wood burners or even lighting candles. Although January was the most polluted month globally, the U.S. saw a particularly flat curve, showing a less marked difference between pollutant levels through the seasons – as compared with European or other Northern Hemisphere geographies.

Cone Aerodynamics uses the Coanda effect to merge two streams of air over a smooth surface, resulting in a powerful and condensed jet of air that can be projected of more than 32 feet, with minimal noise. It delivers more than double the airflow of the previous generation Dyson Purifiers¹¹. Powerful projection is critical to ensure that the machine effectively delivers clean air to every corner and displaces dirty air back towards the filter. The Dyson Purifier Big+Quiet Formaldehyde projects purified air at angles of 0^o, 25^o or 50^o depending on user preference.

PM2.5 annual average: A striking regional picture

When looking at the data from Dyson connected purifiers throughout 2022, there are some striking results when ranking countries on their average PM2.5 level. Regionally, the U.S. (26th) outranks Canada (27th), but Mexico ranks highest at 7th on average PM2.5 levels. Rankings aside, all countries studied exceeded the WHO annual guideline for PM2.5 (5 µg/m3) – with Mexico registering more than three times the annual guideline. 

Similar to the country-level data, every city studied exceeded the WHO long-term or annual exposure guideline for PM2.5 (5 µg/m3). In the Americas, Mexico City is the highest ranked city, and also sits within the top 10 (9th). Los Angeles ranks next (20th) while Chicago sits just below Toronto and New York. Mexico City exceeded the WHO guideline by three times and Los Angeles by two times, registering an annual average PM2.5 level of 18.24 µg/m3 and 11.59 µg/m3 respectively.

VOC annual average: The U.S. is an outlier

When it comes to VOCs, most geographies experienced a u-shaped curve, registering higher VOCs in the evening and early hours of the morning, compared to the middle of the day. The U.S., Canada and Mexico were no exception to the trend, however they experienced a clear second spike – not higher than the peak concentration but clearly a spike – in the mornings. At a city level, data typically followed national averages – the U.S. and Mexico, among others, being the exception where there is some spread.

Evening pollution higher than any other time of day

In most countries studied, indoor PM2.5 levels were highest during the evening and night-time hours, coinciding with the time that the majority of people spend in their homes, rather than being out at work, school or elsewhere. Exposure is the measure of air pollution concentration over time, which within the air quality research community is a key consideration – a spike of air pollution (a very high level for a short period of time) is not necessarily worse than prolonged exposure to ‘poor’ or even ‘fair’ air quality. Therefore, data from Dyson purifiers suggests that this longer, more polluted period may account for increased exposure to PM2.5 in homes. Peak hours globally were between 6 p.m. and midnight in most geographies, including the U.S.

Low uptake of Auto mode globally

Globally, these connected air quality data insights show that just 8% of Dyson purifiers spent more than three-quarters of the time in Auto mode – where the machine constantly monitors the air quality and automatically responds to changing pollution levels – suggesting that most Dyson purifiers in homes across the world were not being used to automatically manage indoor pollution events. Despite the number of complex variables at play, when used in Auto mode, Dyson purifiers intelligently adjust to reach their target air quality, giving owners the best purification from their machines.