People considered Florence Nightingale a wild-eyed fanatic when she wrote at length on the dangers of stale air. But we’ve come a long way since those days. In our enlightened times, we know the very gases that pollute our environment.We even have a label for the tiredness, headaches, fuzzy thinking and strained eyes that result from living in stale air: sick building syndrome.Yet many of us work and sleep in poorly ventilated offices and homes. If you spend many hours a day in stuffy rooms, you’re probably experiencing some of those symptoms – even a high pulse and difficulty breathing. What’s happened is that carbon dioxide has built up in your environment, depriving you of oxygen.Where humans and pets work or live in closed rooms, carbon dioxide accumulates because mammals inhale oxygen but exhale CO2.Modern homes and workplaces contain oxygen-guzzlers like a space heater, clothes dryer or gas stove. Rural homes often have wood-burning stoves, which give off a lovely odor and warmth but also eat up oxygen. Our safe rooms, built of reinforced concrete, are often turned into extra bedrooms or offices. While we bless their resistance to rocket fire, they’re also traps for accumulated CO2. The gas pools in basements and lower floors as well, being one and a half times heavier than air. And when the weather turns cold, we tend to seal off the home and put up with stuffy rooms in order to stay warm.While that’s understandable, it’s an effective way to accumulate CO2 in the air.Several years ago, an entire family of new olim from Russia suffocated in their sleep; they had shut off all ventilation and kept a room heater on high for many hours. It sounds dire, but the good news is that ventilating the area disperses CO2 quickly. Instinctively you open a window to clear out the stuffy air and let fresh air in. To ventilate even faster, install a fan in front of a window, facing front, so that it’ll push air in from the outside. The fan doesn’t have to be in the window ledge, as long as it’s in front of the window. There are whole-house ventilation systems, which require the expertise of a professional contractor, but in our mild Israeli winters, it’s usually possible to ventilate at least a few minutes in every room, a few times a day. And it’s wise to maintain your heater/air conditioner clean and in good shape at all times, especially after house repairs, which may have released debris and particles into the rooms.A NASA study published in 1989 indicated that house plants may filter air and lower pollution. This gave rise to a popular belief that a few potted plants around the house guaranteed a clean environment.But the United States Environment Protection Agency, in more recently published guidelines for health professionals, says this: “As a practical means of pollution control, the plant removal mechanisms appear to be inconsequential compared to common ventilation and air exchange rates. In other words, the ability of plants to actually improve indoor air quality is limited in comparison with provision of adequate ventilation.”It seems that the home-owner would have to fill the house with dozens of potted plants to benefit from their air-cleaning properties. And to keep them efficient, he’d have to keep their leaves dust-free – meaning lots of time with buckets of warm water and a soft rag, every day. But your ficus and ferns may act as the canaries in the coal mine: If they’re growing much faster than normal, you may suspect a high level of CO2 in the house, because house plants thrive where there’s plenty of it in the air.CO2 occurs naturally in the earth’s atmosphere and acts as a heat trap, collecting energy from the sun and from activity on earth. Trees and plants use it during photosynthesis, scrubbing excess out of the air. With much of the earth’s jungles and forests being cleared for crops, the planet’s air-cleaning resources are thinning out. Fuels that burn, especially fossil fuels, release carbon, which reacts with oxygen and makes CO2.Global warming is a reality as CO2 levels rise, making the earth a hotter place for every living creature. Consequences are grim and include global malnutrition.Researchers at Ben-Gurion University are predicting that high levels of CO2 will reduce zinc and iron in wheat, rice, corn, sorghum, soybeans and field peas – grains that sustain two billion people almost exclusively. With staple grains nutritionally poorer, those people will be at a significant risk of starvation.A DEPRESSING picture, but each person can do something to reduce atmospheric CO2. To start, consider ways to reduce waste. Landfills full of organic matter emit heat like Shabbat hot-plates. Reduce the amount of overall garbage you throw out, to keep landfills smaller and cooler. To reduce food waste, keep this motto in mind: Cook everything you buy, and eat everything you cook. Donate used clothing. Recycle everything you can. Even recycling burns up energy, but it takes up much less than making plastics, glass and paper from raw materials. Next time you’re out on the highway, count how many cars have only one passenger, the driver. That’s lots of CO2 in the service of one individual.Burn less fossil fuel by taking public transportation or forming a carpool with friends or neighbors. Do you need to run a quick errand in the neighborhood? Walk there instead of taking the car out. Your waistline will come down and so will your gas bill, and there will be that much less CO2 in the air. Get your neighbors together and make a communal bonfire on Lag Ba’omer, instead of each family making one.Plant trees. Join Keren Kayemeth LeIsrael- Jewish National Fund tree-planting junkets, or donate a tree. If you own a garden, plant a lovely lemon tree. Suggest planting new trees for the building at the next va’ad bayit (apartment building residents’) meeting.Anything with a red LED light is still eating up electricity, even if the appliance is turned off. You really can get used to unplugging your washer, dryer, computer and music station, although obviously not your refrigerator. After a few times, it’ll become automatic. And if someone in the house objects, you have the moral high ground.If you or others living in your home experience symptoms more severe than those described above, don’t assume it’s from CO2. The culprit might be deadly and rapidly-acting carbon monoxide from a leaky gas heater or a faulty pipe.If that’s the case, turn off all gas faucets, ventilate the home, and call the gas company’s local branch or national call center. According to the National Infrastructure, Energy and Water Ministry, “the gas company is legally obligated to promptly arrive at the location of the gas leak. If the gas company fails to arrive, please report to the additional following emergency call centers: Emergency Call Center – Ministry of Environmental Protection: *6911 or the National Emergency Call Center – Israel Fire and Rescue Services: 102.”More information about safe gas use can be found in English at http://energy.gov.il/English/Subjects/CookingGas/Pages/ GxmsMniSafeUsageOfGas.aspx.