We think it’s important to show how low-cost purifiers can truly help people protect their health clean air, which is why we calculated the number of “clean breaths delivered.” And since we’re nerds, we want to be specific about how we calculated it:

Let’s start with 1,000 purifiers as an example. Humans breathe around 15 breaths per minute. A conservative estimate is that people leave their purifiers on while preparing for bed and sleeping, which should add up to around 8 hours per day. Let’s also be conservative and say people turn their purifiers on only half of the days in a year. (Here in Beijing, we use our purifiers closer to every day!) To be extra conservative, we presume that each purifier is being used by just one person. That ignores people who share bedrooms and living rooms!

Here’s how that math works out:

Number of purifiers: 1,000

Average breaths per minute: 15

Daily purifier usage: 8 hours per day

Percentage of the year people use purifiers: 50%

With all of this information, we can work out the average number of clean breaths Smart Air provides every minute, or every second

Breaths per minute = No. purifiers × No. breaths per minute × daily purifier usage/24 × percentage of the year purifiers are used

Breaths per minute = 1,000 × 15 × 8/24 × 0.5 = 2,500 breaths per minute!

Breaths per second = 2,500/60 = 42 breaths per second.

To get the total number of breaths per minute or second, we looked back at when we first started selling purifiers (January 2014) and calculated the number of seconds since then. Assuming our growth has been linear (when we first started we’d sold 0 purifiers, now we’ve sold 1,000, increasing by the same value every month), we can take take the average number of purifiers used since January 2014 to be half (/2) the number of purifiers sold (500 purifiers).

Seconds from 1st January 2014 until now (1st September 2016): 84,193,659 seconds

Using our example of 1,000 purifiers, we can calculate:

Total clean breaths delivered = 84,193,659 × 42 / 2

Total clean breaths delivered = 1,768,066,839

Breathe safe!