The author says: The few pedestrians on the streets are mostly unmasked, confirming fears that public awareness of the health risks are
low.
Low? Should it be high?
Because on the streets there are only very few people (pedestrians) there, while most people stay indoors. So the public awareness of the health risks of smog is high.
If you argue that the few pedestrians are mostly unmasked, so their awareness of the risks is low. Yes, it is true. But not true in the context of general public.
Or you may argue it says "fears are low" (not the awareness are low). Yes, and it is only for the few pedestrians, not for general public (most of them stay indoors!)
So, how to understand the logic?
Context:
(Barely) living in smog: China and air pollutionThe Lancet
There are few cities in the world where the first thing you do on waking is check the air quality app on your mobile phone—even before switching off the alarm. Beijing is such a city. On Feb 25, Beijing had been shrouded in heavy smog and hazardous levels of respirable fine particulate matter (PM2·5) for 6 consecutive days. That morning the PM2·5 level read 383 μg/m3, which is 15 times the recommended safe WHO limit (25 μg/m3 for 24-h PM2·5), but not the worst reported in a week when levels soared to 500 μg/m3. You wake your young child who you have kept at home for 2 days and switch the air purifiers up to high. You explain that at school today they will stay inside to play. Outside, the air is smoky and the sky a sunless thick grey yellow. A sheet of dust covers most vehicles and surfaces and you can almost taste it through your face mask. You call a taxi for a school run that on clear days is a 20 min walk. The driver can see no more than 150 metres ahead in the haze.
The few pedestrians on the streets are mostly unmasked, confirming fears that public awareness of the health risks are low, or that some simply do not have the choice. There is a lone jogger ignoring the orange alert (the second highest level in a four-tiered system) issued for the very first time by the Beijing Environmental Bureau, closing industrial plants and advising people to stay indoors and to refrain from exercise.
MOre:
http://www.thelancet.com/journals/lancet/article/PIIS0140-6736%2814%2960427-X/fulltext