Breathe easy, Vancouver: Your worst air pollution would be welcome relief in Hong Kong
Vancouver’s recent smog alert can’t match everyday pollutant levels in the SAR
I’ll wager I wasn’t the only former Hong Kong resident who cocked an eyebrow last week when Metro Vancouver authorities issued a rare air-quality advisory.
Residents were told to avoid strenuous outdoor exercise at certain times, with air conditions said to be of particular concern to infants, the elderly and the sick. Those already suffering ill-effects such as shortness of breath were told to stay indoors.
Such warnings might be commonplace in smoggy Hong Kong, but Vancouver?
The sense of discombobulation was enhanced by the gorgeous run of weather Vancouver was enjoying - clear blue skies and sunshine in brilliant abundance. If the warnings to stay indoors had any effect, it wasn’t on the happy hordes whose reddening bodies littered local parks like battle dead after the War of the Bikinis.
The only air pollutants I could detect were suntan lotion, barbeque smoke and the skunky whiff of BC bud that seems to accompany every merry outdoor activity in these parts.
So what gives? Should Hongkongers looking for a clean-air bolthole really be considering options other than Vancouver?
Last-week’s advisory, issued on July 13 and lifted on July 15, applied particularly to high levels of ground-level ozone (O3), otherwise known as smog. The very sunshine and calm conditions that helped pack local parks and beaches triggered the buildup of ozone (which is created when sunshine reacts with other pollutants) and then trapped it with other pollution.
How bad was it? By Vancouver standards, pretty bad - the advisory was only the fifth issued since 2006, according to The Province newspaper. BC environment ministry data showed that ozone levels at the Robson Square monitoring station in Vancouver’s downtown core peaked during the advisory period at 31.7 parts per billion at noon on July 13. A molecular weight conversion shows this to be equivalent to 63.4 micrograms per cubic metre of air, far exceeding the WHO’s recommended maximum of 23.5 micrograms per cubic metre. At Vancouver International Airport (YVR) in nearby Richmond, ozone levels topped out at 88.8 micrograms per cubic metre.
By coincidence Vancouver’s smog alert came in the same week that the Clean Air Network said ozone levels in Hong Kong were at their worst level in nearly a decade, averaging 43 micrograms per cubic metre for the first six months of the year, based on data from all of the city’s monitoring stations.
Yet anyone worried that Vancouver’s pollution is on par with (or exceeds) Hong Kong’s need not worry.
Robson Square’s 63.4 microgram ozone level represented a one-hour maximum. During the three full days the smog advisory was in place, ozone levels at Robson Square averaged 23.8 micrograms per cubic metre. In other words: The air in Vancouver’s downtown core during what was supposedly the worst pollution in years was twice as clean as that which all of Hong Kong endures, on average, every single day.
The average levels of other pollutants in Hong Kong also routinely and vastly exceed the worst that Vancouver can dish up. During Vancouver’s three-day alert, nitrogen dioxide (NO2) levels in Robson Square averaged 17.5 parts per billion, or 32.9 micrograms per cubic metre. Yet according to the Hong Kong government’s Air Quality Health Index, NO2 levels across the SAR averaged 67.4 micrograms per cubic metre at all available monitoring stations in the year to February 2014. At the roadside stations of Central and Causeway Bay, NO2 levels averaged 121 micrograms.
What about the particulate pollution that has been implicated in serious health problems and causes so much concern in Hong Kong? The Robson Square station does not monitor PM10 or the smaller PM2.5 particulates, but the Vancouver airport station does, and it reveals levels that are startlingly low compared to the SAR.
In Hong Kong, in the year to February, PM10 levels averaged 49.6 micrograms per cubic metre across the territory, and PM2.5 levels averaged 32.6. But at YVR, PM10s registered a mere 15 during the three-day pollution alert, and PM2.5s just 8.8.
And don’t forget, this was during a period when air pollution in Vancouver was front-page news. YVR’s average particulate readings for the same 12-month period as the Hong Kong data are considerably lower again: 11.5 micrograms per cubic metre for PM10 particulates and 6.5 for PM2.5 particulates.
So breathe easy Vancouver. There might be plenty of reasons for Hongkongers to feel at home here, but air pollution isn’t one of them.
The Hongcouver blog is devoted to the hybrid culture of its namesake cities: Hong Kong and Vancouver. All story ideas and comments are welcome. Connect with me by email email@example.com or on Twitter, @ianjamesyoung70.