2012 July 18 Wednesday
Trees And Bushes Cut City Pollution

More greenery would be good for our lungs.

Trees, bushes and other greenery growing in the concrete-and-glass canyons of cities can reduce levels of two of the most worrisome air pollutants by eight times more than previously believed, a new study has found. A report on the research appears in the ACS journal Environmental Science & Technology.

Thomas Pugh and colleagues explain that concentrations of nitrogen dioxide (NO2) and microscopic particulate matter (PM) both of which can be harmful to human health exceed safe levels on the streets of many cities. Past research suggested that trees and other green plants can improve urban air quality by removing those pollutants from the air. However, the improvement seemed to be small, a reduction of less than 5 percent. The new study sought a better understanding of the effects of green plants in the sometimes stagnant air of city streets, which the authors term "urban street canyons."

Climbing ivy cuts nitrogen dioxide and particulate pollution.

The study concluded that judicious placement of grass, climbing ivy and other plants in urban canyons can reduce the concentration at street level of NO2 by as much as 40 percent and PM by 60 percent, much more than previously believed. The authors even suggest building plant-covered "green billboards" in these urban canyons to increase the amount of foliage. Trees were also shown to be effective, but only if care is taken to avoid trapping pollutants beneath their crowns.

Plants are good for our health. Cities should plant more of them.

By Randall Parker    2012 July 18 11:10 PM   Entry Permalink | Comments (2)
2011 January 16 Sunday
Cigarette Smoke Damages DNA Quickly

The damage starts right away.

WASHINGTON, Jan. 15, 2011 In research described as "a stark warning" to those tempted to start smoking, scientists are reporting that cigarette smoke begins to cause genetic damage within minutes not years after inhalation into the lungs.

Their report, the first human study to detail the way certain substances in tobacco cause DNA damage linked to cancer, appears in Chemical Research in Toxicology, one of 38 peer-reviewed scientific journals published by the American Chemical Society.

When I see friends smoke cigarettes it is frustrating. I see damage being done.

The scientists followed a labeled polycyclic aromatic hydrocarbon (PAH - think of a bunch of carbon rings not fully saturated with hydrogens) and saw it very quickly convert into a more toxic form. The report doesn't say but I'm guessing epoxidation.

The scientists added a labeled PAH, phenanthrene, to cigarettes and tracked its fate in 12 volunteers who smoked the cigarettes. They found that phenanthrene quickly forms a toxic substance in the blood known to trash DNA, causing mutations that can cause cancer. The smokers developed maximum levels of the substance in a time frame that surprised even the researchers: Just 15-30 minutes after the volunteers finished smoking. Researchers said the effect is so fast that it's equivalent to injecting the substance directly into the bloodstream.

Do not smoke and also strongly object to second hand smoke.

By Randall Parker    2011 January 16 11:09 PM   Entry Permalink | Comments (4)
2009 November 02 Monday
Small Walkable And Breathable Neighborhood Overlap

A study in Vancouver BC finds that very few people live in ideal neighborhoods that feature both high walkability and clean air.

A new study compares neighborhoods' walkability (degree of ease for walking) with local levels of air pollution and finds that some neighborhoods might be good for walking, but have poor air quality. Researchers involved in the study include University of Minnesota faculty member Julian Marshall and University of British Columbia faculty Michael Brauer and Lawrence Frank.

I find these results to be important reminders on the value of electric vehicles. Cities and suburbs would both become better for our health if more vehicles were battery powered.

If we had finer granularity maps of pollution I bet it would change housing prices. Just what is the health cost of living 50 yards, 100 yards, or 200 yards from a busy freeway? Also, just driving to work during the busy part of the day is bad because you are right in the lanes breathing soot.

The research team found that, on average, neighborhoods downtown are more walkable and have high levels of some pollutants, while suburban locations are less walkable and have high levels of different pollutants. Neighborhoods that fare well for pollution and walkability tend to be a few miles away from the downtown area. These "win-win" urban residential neighborhoods--which avoid the downtown and the suburban air pollution plus exhibit good walkability--are rare, containing only about two percent of the population studied. Census data indicate that these neighborhoods are relatively high-income, suggesting that they are desirable places to live. Neighborhoods that fare poorly for both pollution and walkability tend to be in the suburbs and are generally middle-income.

I just hate it when an old smelly diesel truck drives by when I'm out for a walk. I see them coming and alter my path to reduce the fume exposure. Sometimes I suck in a big breath just before they pass so I can get upwind of the exhaust before I breathe again.

"The finding that nitric oxide concentrations are highest downtown, while ozone concentrations are highest in the suburbs, is not surprising," said Marshall. "Motor vehicle exhaust is most concentrated downtown, leading to the high nitric oxide concentrations downtown. In contrast, ozone takes time to form. Air masses have moved away from downtown--often, to suburban areas--by the time ozone concentrations reach their highest levels. Thus, reductions in vehicle emissions can benefit people who live near high-traffic areas and also people living in less dense areas."

I think more people who live in polluted areas ought to get HEPA filters. Also, again, this report is an argument for electric cars and trucks.

By Randall Parker    2009 November 02 10:15 PM   Entry Permalink | Comments (0)
2009 August 31 Monday
Commuter Tunnels Heavily Polluted

Tip of the day: Roll up your windows before passing thru car tunnels.

A toxic cocktail of ultrafine particles is lurking inside road tunnels in concentration levels so high they have the potential to harm drivers and passengers, a new study has found.

The study, which has been published in Atmospheric Environment, measured ultrafine particle concentration levels outside a vehicle travelling through the M5 East tunnel in Sydney.

A tunnel in Sydney Australia sometimes has particulate pollution 1000 times higher than in the surrounding environment. Mind you, cities are already more polluted than suburbs or countryside.

Professor Morawska said the study involved more than 300 trips through the four kilometres of the M5 East tunnel, with journeys lasting up to 26 minutes, depending on traffic congestion.

"What this study aimed to do was identify the concentration levels found in the tunnel. It generated a huge body of data on the concentrations and the results show that, at times, the levels are up to 1000 times higher than in urban ambient conditions," she said.

Motorcycling thru tunnels doesn't give you much opportunity to avoid exposure. At least with cars you can roll up your windows.

She said drivers and occupants of new vehicles which had their windows closed were safer than people travelling in older vehicles.

"People who are driving older vehicles which are inferior in terms of tightness and also those riding motorcycles or driving convertibles, these people are exposed to incredibly high concentrations," she said.

If you have to do this regularly and want to cruise through polluted tunnels on a motorcycle you could use an N95 respirator.

A engineer friend tells me that HEPA filters aren't practical in cars due to weight and energy requirements. But you could outfit your car with a HEPA filter if you didn't mind teh costs. I've long wondered just how much pollutants make it inside commuter cars in dense traffic. Anyone have insights on this?

By Randall Parker    2009 August 31 05:36 PM   Entry Permalink | Comments (9)
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