Dear EarthTalk: How does growing human population, and its resultant landscape changes, affect the flight paths of migratory birds that might carry diseases? – Ronnie Washines, Toppenish, WA

As human population numbers grow, oceans of people seem to spread out into every conceivable environment—even the forests and estuaries used for eons by migratory birds as nutrient-rich stopovers on their longer annual journeys between feeding areas and birthing grounds.

Of course, more human development means fewer habitats suitable for such birds of passage (and other wildlife) as we "pave paradise…" and put up parking lots. But tired and hungry birds may not have the wherewithal or instinctual coding to seek out alternative resting areas, so they make do with habitat crowded and compromised by human incursion. Close proximity to avian life hasn’t presented too big of a problem for people in the past, but new concerns about the spread of bird flu (the H5N1 virus) via infected migratory birds (which presumably infect local populations of domestic birds) does have some scientists worried that persistent human expansion could indirectly lead to a disease pandemic of global proportions.

According to the World Health Organization (WHO), the role of migratory birds in spreading bird flu is not well understood, but we do know that wild waterfowl are a "natural reservoir" of mostly harmless H5 and H7 influenza A viruses. But recent research suggests that these viruses may be mutating into more "pathogenic" (disease producing) forms, such as H5N1 that can "jump the species barrier" and infect people and other animals. "Recent events make it likely that some migratory birds are now directly spreading the H5N1 virus in its highly pathogenic form," reports WHO, adding that further spread to new areas is expected. It is unlikely that the bird flu making headlines a few years ago (the H5N1 strain), could lead to a human pandemic. The vast majority who got sick had direct contact with infected birds.

It could be that the very sprawl that increases our chances of catching bird flu—by bringing us and our poultry farms into closer contact with disease-bearing migratory birds—will protect us in the end. Humans have greatly altered the landscape for agricultural and industrial purposes and in creating urban settlements, points out wildlife biologist Kevin Kenow of the U.S. Geological Survey’s Upper Midwest Environmental Sciences Center. As such, it contains less of the kinds of habitat migrating birds prefer—wetlands, forests and prairies—and more of what adversely affects them, such as human development, urban and agricultural runoff, and other forms of habitat degradation. "Many migratory birds that once flourished are now absent in altered or degraded areas,” he says.

Regardless of the risk, scientists have yet to develop a vaccine to protect against H5N1 in humans, but they are working on it. Those who remain concerned should always cook poultry to a temperature of at least 158 degrees Fahrenheit for 30 minutes (this heat kills the virus if it is present) and wash hands with soap and warm water frequently (always a good idea regardless). And look both ways before crossing the street: At present, at least, your chances of getting hit by a car are far greater than your chances of contracting bird flu.

CONTACTS: World Health Organization, www.who.int; U.S. Geological Survey’s Upper Midwest Environmental Sciences Center, www.umesc.usgs.gov.

Dear EarthTalk: Since nitrogen oxide compounds are components of smog and are common water pollutants, does nitrogen-enriched gasoline create additional pollution? – Rick Oestrike, Poughkeepsie, NY

It might seem like adding nitrogen to gasoline is all the rage among oil companies today, but the idea has been around for years. The U.S. Environmental Protection Agency (EPA) requires that automotive fuels sold in the U.S. contain detergents to help scrub away pollution before it goes out the vehicle’s tailpipe. Some manufacturers have found that adding nitrogen to the detergent helps keep an engine cleaner by reducing the carbon build-up in the gas tank that can in turn "gunk" up the engine and lower performance.

The nitrogen itself also has a direct cleaning effect, breaking down carbon deposits that can harden on an engine’s moving parts. "If too much collects, this gunk can negatively affect engine performance, causing your car to burn more oil, overheat and burn gasoline less efficiently," reports John Fuller on the How Stuff Works website. Valves inside an engine are designed to let in a specific amount of air and fuel, he adds; when that process is slowed by carbon build-up, a car won’t perform up to its potential.

But while nitrogen-enriched gasoline may provide a slight bump in engine performance, some worry about adding to cars’ already substantial pollution load, especially nitrogen oxide (NOx), which contributes to smog, acid rain and other environmental problems. Andr© L. Boehman, a Penn State University engineering and fuel science professor, says that the addition of more nitrogen to the fuel mix "generally will increase NOx emissions." Boehman would like to see more research done so we can know for sure if and how much additional NOx pollution is caused by the use of nitrogen-enriched gasoline.

For its part, Shell Oil, which last spring launched its own form of nitrogen-enriched gasoline now for sale at all of its U.S. filling stations (it is mixed into all three grades of gasoline the company sells), denies that the additional nitrogen has any substantive impact on pollution levels. "Most nitrogen in vehicular NOx emissions does not come from gasoline," the company told The New York Times. "The nitrogen is primarily from the incoming air that mixes with gasoline inside an engine. NOx is produced when the nitrogen from the air reacts with oxygen under high engine temperature and pressure conditions."

Professor Boehman concedes that "the detergent additive may have such beneficial effects on engine operation, fuel system performance and other related features of engine system operation that they outweigh the adverse effect" of increased NOx emissions. "For instance, if improved detergency helps to increase fuel efficiency so that you burn less fuel, you may slightly increase the NOx emissions rate per gram of fuel burned, but end up with lower NOx because you burned fewer grams of fuel."

That said, it is probably a good idea to avoid putting nitrogen in your fuel unless you’re sure the gains will outweigh the detriments. And until researchers know more, drivers might focus instead on minimizing their own vehicles’ overall gasoline consumption and fuel efficiency—and on substituting other cleaner forms of transportation (walking, biking, mass transit) whenever possible.

CONTACTS: EPA Fuels and Fuel Additives, www.epa.gov/OMS/fuels.htm; How Stuff Works, www.howstuffworks.com; Shell, www.shell.us.

SEND YOUR ENVIRONMENTAL QUESTIONS TO: EarthTalk®, P.O. Box 5098, Westport, CT 06881; earthtalk@emagazine.com. Read past columns at: www.emagazine.com/earthtalk/archives.php. EarthTalk® is now a book! Details and order information at: www.emagazine.com/earthtalkbook.

Summertime is fast approaching (forty days away actually — not that we’re counting or anything) which, between the kids being out of school and those oh-so-exciting family road trips to visit the world’s largest spoon in the middle of Wyoming, means there’s a lot of gas to burn driving around. With the stock market in the tank and layoffs abounding, Americans are already feeling the pinch as it is, but one company is trying to take the pain at the pump out of the equation.

Petrofix, a San Francisco based company, allows consumers to lock in a gas price for a set amount of time. When gas prices go up, the company will actually cut you a check at the end of the month for the increased prices. If gas prices go down, you still get to benefit from the lower gas prices. Essentially, you’re getting an insurance policy against over-paying for gas, except there’s no paperwork to file and red tape to cut through; your credit card is just automatically credited at the end of the month if average gas prices rise above the rate that you locked in.

There are no enrollment fees, which is nice. You pay around $0.25 a gallon, depending on current gas prices and which region of the country you live in, for the number of gallons you’ll use in a month over the length of the period you want to purchase gas for. The Petrofix site includes tools to estimate your gas usage.

Obviously, as gas prices go way down, you still might end up at a bit of a loss, but this is certainly a lot simpler than participating in securities and commodities markets.

Dear EarthTalk: I am looking at possibly buying a house that is very close to a gasoline station. Is it safe to live so close to a gas station? What concerns should I have? I have toddler and infant babies. — Ranjeeta, Houston, TX

Despite all the modern health and safety guidelines they must follow, gas stations can still pose significant hazards to neighbors, especially children. Some of the perils include ground-level ozone caused in part by gasoline fumes, groundwater hazards from petroleum products leaking into the ground, and exposure hazards from other chemicals that might be used at the station if it’s also a repair shop.

Ozone pollution is caused by a mixture of volatile organic compounds, some of which are found in gasoline vapors, and others, like carbon monoxide, that come from car exhaust. Most gas pumps today must have government-regulated vapor-recovery boots on their nozzles, which limit the release of gas vapors while you’re refueling your car. A similar system is used by the station when a tanker arrives to refill the underground tanks. But if those boots aren’t working properly, the nearly odorless hydrocarbon fumes, which contain harmful chemicals like benzene, can be released into the air.

Higher ozone levels can lead to respiratory problems and asthma, while benzene is a known cancer-causing chemical, according to the National Institutes of Health (NIH). The quest to reduce ozone levels has led the state of California to implement a more stringent vapor-recovery law, effective April 1, 2009, which requires that all gasoline pumps have a new, more effective vapor-recovery nozzle.

Underground gasoline storage tanks can also be a problem. The U.S. Environmental Protection Agency (EPA) estimates that there are some 660,000 of them from coast-to-coast. Many a lawsuit has been filed against oil firms in communities across the country by people whose soil and groundwater were fouled by a gas station’s leaking underground storage tank. In the past, most tanks were made of uncoated steel, which will rust over time. Also, pipes leading to the tanks can be accidentally ruptured.

When thousands of gallons of gasoline enter the soil, chemicals travel to groundwater, which the EPA says is the source of drinking water for nearly half the U.S. If buying a home, consider its potential loss in value if a nearby underground storage tank were to leak. Gasoline additives such as methyl tertiary-butyl ether (MTBE), which has been outlawed in some states, make the water undrinkable-and that is only one of 150 chemicals in gasoline. Repeated high exposure to gasoline, whether in liquid or vapor form, can cause lung, brain and kidney damage, according to the NIH’s National Library of Medicine.

Spilled or vaporized gasoline is not the only chemical hazard if the station is also a repair shop. Mechanics use solvents, antifreeze and lead products, and may work on vehicles that have asbestos in brakes or clutches. Auto refinishers and paint shops use even more potentially harmful chemicals.

In today’s car-centric world, we can’t escape exposure completely, because these chemicals are in our air just about everywhere. But by choosing where we live, keeping an eye out for spills, and pressuring the oil companies to do the right thing for the communities they occupy, we can minimize our exposures.

CONTACTS: U.S. EPA, www.epa.gov; National Institutes of Health, www.nih.gov.

Dear EarthTalk: Do zoos have serious programs to save endangered species, besides putting a few captives on display for everyone to see? – Kelly Traw, Seattle, WA

Most zoos are not only great places to get up close to wildlife, but many are also doing their part to bolster dwindling populations of animals still living free in the wild. To wit, dozens of zoos across North America participate in the Association of Zoos and Aquarium’s (AZA’s) Species Survival Plan (SSP) Program, which aims to manage the breeding of specific endangered species in order to help maintain healthy and self-sustaining populations that are both genetically diverse and demographically stable.

The end goal of many SSPs is the reintroduction of captive-raised endangered species into their native wild habitats. According to the AZA, SSPs and related programs have helped bring black-footed ferrets, California condors, red wolves and several other endangered species back from the brink of extinction over the last three decades. Zoos also use SSPs as research tools to better understand wildlife biology and population dynamics, and to raise awareness and funds to support field projects and habitat protection for specific species. AZA now administers some 113 different SSPs covering 181 individual species.

To be selected as the focus of an SSP, a species must be endangered or threatened in the wild. Also, many SSP species are “flagship species,” meaning that they are well-known to people and engender strong feelings for their preservation and the protection of their habitat. The AZA approves new SSP programs if various internal advisory committees deem the species in question to be needy of the help and if sufficient numbers of researchers at various zoos or aquariums can dedicate time and resources to the cause.

AZA’s Maryland-based Conservation and Science Department administers the worldwide SSP program, generating master plans for specific species and coordinating research, transfer and reintroductions. Part of this process involves designing a “family tree” of particular managed populations in order to achieve maximum genetic diversity and demographic stability. AZA also makes breeding and other management recommendations with consideration given to the logistics and feasibility of transfers between institutions as well as maintenance of natural social groupings. In some cases, master plans may recommend not to breed specific animals, so as to avoid having captive populations outgrow available holding spaces.

While success stories abound, most wildlife biologists consider SSP programs to be works in progress. AZA zoos have been instrumental, for instance, in establishing a stable population of bongos, a threatened forest antelope native to Africa, through captive breeding programs under the SSP program. Many of these captive-bred bongos have subsequently been released into the wild and have helped bolster dwindling population numbers accordingly.

Of course, for every success story there are dozens of other examples where results have been less satisfying. SSP programs for lowland gorillas, Andean condors, giant pandas and snow leopards, among others, have not had such clear success, but remain part of the larger conservation picture for the species in question and the regions they inhabit

CONTACTS: AZA’s Conservation & Science Program, www.aza.org/Conscience.

SEND YOUR ENVIRONMENTAL QUESTIONS TO: EarthTalk, P.O. Box 5098, Westport, CT 06881; earthtalk@emagazine.com. Read past columns at: www.emagazine.com/earthtalk/archives.php. EarthTalk is now a book! Details and order information at: www.emagazine.com/earthtalkbook.

Friday, from 6 a.m. “until the pumps run dry,” Electronic Arts is giving away free gas to anyone who happens to be down on Beverly Boulevard on Los Angeles (corner of La Cienga and Beverly, btw) as a promo for its upcoming game “Mercenaries 2: World in Flames.”

In “Petrol to the People”EA is going guerrilla, — or is it viral? — grassroots? — to promote their newest game. The entire gas station will be decked out in Mercenaries 2 branding and will feature actors dressed up as Mercenaries pumping gas.

“Mercenaries 2: World in Flames is an open-world action game set in Venezuela — a lightening rod in the global debate around energy policy and oil production,” EA said in a statement Friday. “The games story is ripped from today’s headlines.”

“The story of the game is set in a world where countries rich in oil have found new power. That power corrupts, and in Venezuela, corruption has sparked a political coup. A power hungry tyrant uses Venezuela’s oil supply to overthrow the government and turns the country into a war zone. Players step into the role of a mercenary for whom politics doesn’t matter.”

The entire event will be webcasted live on Break.com at www.break.com/mercenaries2.

For more info on Mercenaries 2: World in Flames, tune to its official website. The game will be available for the PlayStation 3, Xbox 360, PC and PlayStation 2