Previously, I wrote about what the definition is for safe air quality as defined by the World Health Organization (WHO) here. The short version is that the WHO defined PM2.5 of 10 μg/m3 (10 micrograms per cubic meter of air) as the maximum “safe” level. If the goal for outdoor air quality is for a PM2.5 of 10 or below, it is only natural that this is what we should try to maintain in our homes as well. Ideally, the goal should be for zero particulate matter in the air, but no higher than 10.
Unfortunately, in the six years that I’ve lived in Beijing, almost no one has really been talking about this. Sure, everyone talks about the problem of Beijing’s air quality and how bad it is – people seem to love posting up high or relatively low AQI readings on WeChat – but mostly what I hear are generalizations. So, if below 10 is the goal, how do you reach that goal at home and how do you know you’ve reached it?
To find out, I invited Charlie Thomson of Environment Assured to come in and test our air quality. We run one IQ Air unit in the living room and three Blue Air units in the bedrooms, so I figured we were doing our part to make the home safe; after all, everyone agrees that you need to get air filters. Charlie laid out three important steps to make the home safe against particulate matter.
Step 1 – Seal Leaks
As Charlie went around our home measuring the particulate levels with our filters running normally, he also measured the levels leaking in from windows, fan vents, duct work, the vacuum, and drains (yes, your drains don’t just smell bad, they also send up PM2.5). It was clear from the readings on his equipment that we had brought the particulate levels down, however the leaks in the home were preventing us from staying below PM2.5 of 10 μg/m3 or even 25 in some areas. So we have some sealing work to do and a vacuum to replace (our 10 year old vacuum is spewing out PM2.5 over 100).
Step 2 – Proper Coverage
In our case, we probably need to add two more machines to ensure we have enough coverage to keep the home safe – an additional unit in the living room and one in the office. The discussion was never about brands but about the necessary number of Air Changes per Hour (ACH). The ideal coverage in a room is to have 5 ACH. This means the volume of air in the room runs through the filter 5 times in one hour. We are happy with the IQ Air and Blue Air units, but if we turn them on high, they both sound like, well, big noisy fans in the rooms. It’s fine to have a machine that can handle a large room, but if it is kept on a low setting, it defeats the purpose. Consequently, since we don’t usually go over setting 4 on the IQ Air, we need another unit in the living room to ensure the air is getting properly circulated.
Step 3 – Maintenance
Having air filters is great, and changing the filters according to the manufacture’s specifications is important, but the machines also need to be kept clean. This means vacuuming lint traps and pre filters and even wiping down areas where fine dust can accumulate. Charlie recommended weekly maintenance for optimal performance. It is also a good idea to check seals around the home periodically. Window and door seals in Beijing typically break down after a couple of years and start to leak.
Once we have sealed things up and added two more filter units, Environment Assured will come back and retest to make sure we’ve reached our goal. Then I hope I can relax and breath a bit easier.
To learn more about Environment Assured and the company’s services you can email firstname.lastname@example.org or call 400-000-8320. If you wait for the options listed in Chinese to finish, someone who speaks English will answer the call.
Photos: TheLugash (flickr)