It’s interesting to see the relation between public perception of a situation and scientific evidence. Toronto’s air quality is a good example. Most of us who live here believe that there are good days and bad days, and that the worst pollution is on those hot, muggy days when even breathing seems to require too much energy. In fact, problems occur in the winter, when an area of high pressure will just sit over the city, locking in all the exhaust fumes.
The Numbeo website, which surveys residents' and visitors' attitudes to the city, reveals that people are satisfied with air and water quality, and other measures of pollution, such as civic garbage disposal and the state of our public parks. But, those ratios might change when the results of a three-year study by U of T engineers sink in. Using sensitive measuring equipment, the engineers were able to produce a pollution map of Toronto, comparing the air quality in individual neighbourhoods. Measuring “ultrafine” particles emitted by vehicles’ exhaust systems, especially those run on diesel, they discovered that areas near major roads are the most polluted. They also found that these particles travel further than was originally thought: up to 280 metres from a roadway. These ultrafine particles are 1000 times smaller than the width of a human hair and can be breathed deep into the lungs. There has been little research so far on the health hazards they pose, and so they are (so far) unregulated.
We do know, however, that car exhaust emissions are dangerous: it is estimated that 90 percent of the CO2 from cars comes from 25 percent of the cars: those with old and badly maintained exhaust systems.
Figures released in the USA last week showed that for the first time in more than a million years, the amount of carbon dioxide in Earth’s atmosphere has reached more than 400 parts per million (ppm). According to analysis in the Guardian, nearly thirty years ago, we reached the limit considered “safe,” 350ppm, but levels have just kept climbing. Since the Industrial Revolution, the level has risen by 120ppm. In the last few years, small, particularly polluted areas have reached the 400-plus level, but March 2015 was the first time it was global.
Unfortunately, even if the climate change summit later this year in Paris is able to work a miracle and somehow we halt the rise of CO2 levels, it will only stabilize the atmosphere and not lower the present levels. That would require a drastic reduction over some time.
We know climate change is real, but people with pollen allergies will have more reason than most to curse it this month. A combination of factors have created a “pollen tsunami,” of grass and tree pollen blowing around at the same time: Dr. Clifford Bassett told New York magazine that the wet winter means pollen producing plants are very healthy this year; high levels of carbon dioxide in cities cause trees to produce three or four times their “natural” rate, and the greenhouse gasses make that pollen “super-charged;” and finally, Bassett explained, cities plant male, pollen-producing trees instead of female, seed-producing trees because seeds mess up sidewalks. So, even more pollen….
Now, will that be Claritin, Reactine, or Aerius with your recycled tissues?