I've been hearing from people asking if they should be biking on the numerous air quality alert days we have had, and will continue to have all summer. Air quality alerts are forecasts for the following day, so not every alert day turns into a day when we actually exceed the AQ standards. (Just as it does not rain every day it is forecast to rain.) Here in Knox County, we have had 5 days that turned into "orange" days versus many more alert days (I have lost count!). Granted, five days is a pretty significant number, considering our hottest weather is still to come (one would assume!).
You can find the current air quality as well as the current forecast online. Put in your own zip code if you wish, but it is a regional map.
It's definitely safe to bike in the mornings because it is generally not until 3 p.m. or later that the ozone level goes above 100 (turning it into an orange day). If you can carpool or take transit home, that would be ideal. I try to bike home slowly so that I am not breathing hard (thus, not taking in as much pollution, and not breathing it as deeply). Not sure if this does much good. There is also the question of what the difference truly is, healthwise, between a day that it reaches 99 and the day that it reaches 101.
I am not an expert on this, and the recommendations change based on new research all the time. Given that, here is some info I have compiled:
From Bad Air Day, Air Quality and Your Health
Dr. Frank Gilliland, an expert in environmental health at the University of Southern California (says) “High levels of ozone reduce lung function and lead to inflammation, or swelling, in the airways...”
Ozone’s effects can come on quickly and linger or even worsen with time. “When people hear it’ll be a bad air day, most expect their breathing will be affected that day. But in fact, they often feel the effects most strongly the next day or the day after,” says Dr. David Peden, an environmental medicine researcher at the University of North Carolina at Chapel Hill.
From Ozone and Your Patients' Health: Training for Health Care Providers
Information from clinical, epidemiological, and animal studies...indicates that exposure to ambient ozone is a risk factor for triggering short and long-term health effects... It is desirable, in general, for people to reduce both their short-term and their cumulative exposure to ozone.
From Health: Air pollution, the invisible threat
“Healthy, active people tend to underestimate the harmful effects of polluted air, because they don’t wheeze or experience chest pain,” says Dryer. “Experiencing no symptoms of anything wrong, they continue to exercise, putting themselves at greater risk.”
Faced with all this data, should we all quit our two-wheel habit? Despite the darkening diesel cloud, spiking asthma rates and proliferation of heart-stopping studies, all the experts assure me that, on balance, cyclists are doing themselves more good than harm.
He suggests changing my daily gym trip to early in the morning, when diesel particulates, ozone and other air pollutants are at their lowest levels, or after nightfall, when trafﬁc abates.
Here is some info from:
How Air Pollution Affects Your Lungs
People who already have serious diseases such as asthma and diabetes, as well as pregnant women and the elderly, are more susceptible to...air pollution. However, people with no apparent problems can develop issues if they are exposed...too long or too often.
Air pollution can affect your lungs by causing coughing, sneezing, watering eyes, shortness of breath and actual asthma attacks (even if you have never had one before). In an asthma attack, your lungs become swollen and your airways shrink, which lessens the amount of oxygen getting to your lungs....
Prolonged exposure has been proven to lead to...lung diseases such as asthma, chronic bronchitis and emphysema....