Even if you haven’t been reading the news, reading the US Consulate’s air reporting site, or checking your iPhone apps, a quick glance at the Shanghai skies shows that something is not right. We’ve been shrouded in a gray haze and I’ve been getting a lot of questions and messages, so decided this merits a post.
So what’s the deal?
For the past week, levels of particulate matter (called PM2.5 or airborne particles measuring 2.5 microns in size or smaller, about 1/30th the width of a human hair) has been hovering between “Unhealthy” and “Very Unhealthy,” which are levels 4 and 5 on the Air Now system (which the US Consulate uses). A level of 1 is best, while 6 is the worst. Last Monday and again this weekend the levels finally reached level 6 “Hazardous” — hence my concern and post now.
Why is this happening?
Experts don’t agree on any single cause. Most likely, it’s a combination of a few things:
* Farmers burn their crops in the fall, so air quality is usually a problem around this season.
* As temperatures fall, people increase use of heaters, raising electricity needs, requiring more energy production, which is predominantly coal-driven. Coal is a major source of particulate pollution.
* Mother nature. Thermal inversion, windless days, and other meteorological effects combine to create conditions for smog to hold in place rather than blow away
What does this mean?
There is a very real, and immediate health effect on almost everyone. In the Great London Smog of 1952, it’s estimated that over only 4 days,12,000 people died and 100,000 fell ill due to the heavy particulates.
* Most common effects: difficulty breathing, harshness in throat when swallowing, elevated blood pressure, increased chances of asthma attacks, headaches (I get these first).
What can you do?
* Stay inside as much as you can as long as levels are high, i.e. in the unhealthy range (>150 micrograms/m3) or limit outdoor exposure to things that don’t increase breathing rate. Feel free to share any of these links to your school administrator if they don’t have a bad air policy.
* If you need to go out, wear a N95-rated mask, which filters out 95% of all particulates down to 0.3 microns in size. This doesn’t mean the cotton masks that ayis and workmen wear, or surgical masks. This is the white mask made by 3M. Contact me if you need some.
* Monitor the air quality outside, which varies by day and time. The consulate is good for hourly readings, and read here to learn what the numbers mean.
* Close your windows. Normally, I encourage ventilating 2-3x per day to rid indoor spaces of all the CO2 and chemical buildup, but as long as outdoor particulate levels are high, minimize ventilation. In the office place, you may have to be proactive. Culturally, Chinese staff like to keep windows open because of a greater concern about chemicals instead of particulate pollution, which is invisible and has no smell.
* Turn on your air filters. On high. See next section.
* Vacuum frequently with a HEPA-filter equipped vacuum and wet wiping or mopping. This will capture and remove settled particulates, which will increase during this time. Vacuuming with a bad vacuum will just suck it in and then spray it out the back, so bad.
So, do filters really work?
Yes. Just as much of medical science is learned during battle, so do environmental consultants learn the most when air is really bad. This morning, I measured the PM2.5 level on my terrace with a laser particle counter at 250 ug/m3 (the US Consulate was reporting 248). Indoors, where I hadn’t ventilated overnight, the level was 180.
* After I opened the windows, the levels increased to 220. I then turned on my air filter and logged readings every two minutes.
* After 20 minutes, level was 80.
* After 40 minutes (total), level was 28.
* After 60 minutes (total), level was 17.
* For reference, the Chinese national draft standards for PM2.5 is <75ug/m3 and the US EPA is <35ug/m3.
* So, in one hour, the filter reduced levels from 220 to 17.
* Note: filters do need to be changed. I measured the PM2.5 levels at the air vent of the air filter in this test unit and it was about 3ug/m3. Downstairs, the exact same filter, but with a filter that was a month overdue for changing (for shame, I know) read 22 ug/m3. (Second note: I have changed that filter.)
* The takeaway is that any HEPA-equipped filter is better than none. They really do work. Some are quieter, some look better, some use less electricity, some are built to last, but anything that is really HEPA-equipped will help you.