One can argue that an annual event such as Earth Hour, coming at 8.30pm on Saturday March 22 in whatever time zone you are located, helps give people an opportunity to reconnect to their support for action on climate change. So far so good, but many of those who participate in Earth Hour replace electric lighting with one or two unhealthy alternatives: candles and flashlights.
Candles are an environmentally poor alternative to electric light. Most candles are made of petroleum wax, a fossil fuel derivative, and the amount of light emitted per unit of petroleum burned is far less than the most inefficient power plant. Many ngos are working to replace oil lamps in homes in developing countries with solar powered LED lighting because of the undesirable environmental and indoor air quality impacts of the oil lamp. Candles are no better than oil lamps. All candles, even those made from beeswax, inevitably emit particulate matter in the form of soot, a material that, when experienced indoors, puts people with asthma at risk of an attack and which is not healthy even for the most healthy of us. We do not need more particulate matter, particularly black carbon particulate matter with a light coating of petroleum, being inhaled into our lungs. If you are concerned about second-hand cigarette smoke, GallonDaily recommends that you avoid rooms where candles are being burned.
Flashlights themselves are not a problem but the used batteries most certainly are. A non-rechargeable dry cell battery of any type has a higher environmental footprint than almost any other form of electricity. Scrap batteries are becoming an increasing component of municipal solid waste and the vast majority, even those designated as household hazardous waste, are not finding their way into recycling programs. If you must use a flashlight, try using a crank powered flashlight or rechargeable batteries and, at the end of their useful life, make sure that all batteries go to recycling. Note as well that even recycling of dry cell batteries is not a particularly energy efficient activity, though it is certainly a great improvement on landfill. And, of course, make sure that your flashlight is an LED type, giving maximum light for minimum battery use.