30 November 2019 | New Scientist | 27hardwired into us as necessary
for our well-being. Earth-scented
gloves and green wallpaper may
be insufficient for their welfare.
Little figures on the ceiling
explained by science
9 November, p 42
From Hillary Shaw,
Newport, Shropshire, UK
You mention the camera obscura
as an example of unconventional
imaging. I saw a camera obscura
after moving into a house with
high ceilings, tall windows and
a short front garden. On a bright
first morning, I saw tiny figures
moving on the ceiling. The folds at
the top of the curtains were acting
as pinholes, projecting pedestrians
on the street onto the ceiling.
Tackling the puzzle of low-
carbon domestic energy
9 November, p 18
From Jeremy Hawkes, Liverpool, UK
As Adam Vaughan says, gas boilers
are a UK election battleground,
with three of the main parties
wanting to phase them out, each
at a different rate. But methane
is a great biofuel that is relatively
easy to make, store and transport.
Sensibly, three times more UK
domestic energy is supplied by gas
than by electricity. So if we remove
gas, we will need four times the
electricity generation capacity.
This is a large price to pay for a
possible 12 per cent carbon saving.
The next government should look
at the low-carbon possibilities for
domestic heating.
We need investment in
insulation and heat recycling to
avoid heat going down the drain,
and into making gas from waste.
From Karen Hinchley, Newark-on-
Trent, Nottinghamshire, UK
I am pleased by the progress
in planning new homes that
Vaughan outlines. But the
suggestion that a space can be
“airtight, but still well-ventilated”
is confusing.
Should air trapped in an airtight
home be recirculated? How would
moisture escape? Dehumidifiers
need electricity and moisture-
absorptive materials have to
be recharged (more electricity
consumption) or replaced
(recycled or landfilled).The editor writes:
We mean only that houses
should be built in a way that
avoids unintentional draughts,
not that no air can get in and out.Recycling heat to save
energy in our home
Letters, 26 October
From Patrick Davey,
Dublin, Ireland
Matthew Allan proposes that we
retrofit homes with integrated
heat-handling equipment. This
is a great idea.
We already have a sealed
house. Its controlled ventilation
incorporates a heat exchanger
working at 92 per cent efficiency.
The only heat we waste is water
from washing machines and
showers. These use only 30 per
cent of the normal water flow. Very
few visitors notice the difference,
and, of course, you don’t heat the
70 per cent you don’t use.One spoonful of tea avoids
plenty of plastic problems
5 October, p 16
From Paul Whiteley,
Bittaford, Devon, UK
You report the pollution and
possible health risks of plastic
particles from teabags. There is
a simple way to avoid these: stop
using teabags. For the price of a
box of teabags that makes 25 cups,
I buy loose tea to make 250 cups. ❚To find more from the archives, visit
newscientist.com/old-scientistViews From the archives
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newscientist.com/lettersTo find more from the archives, visit
newscientist.com/old-scientist35 years ago, New Scientist
was covering the aftermath of the
world’s worst industrial disasterIT WAS a brutal statement of
a brutal tragedy. “Poison gas
leaking from a pesticide plant
killed more than 1000 people
in central India this week, and
injured more than 20 000,”
our correspondent Debora
MacKenzie wrote in our issue
of 6 December 1984. “It was
the sort of mass disaster which
may become increasingly frequent as cities in the
Third World grow and surround factories.”
Thankfully, that hasn’t come to pass, at least not
on the scale of the leak from the plant run by a local
subsidiary of the US-based chemical corporation Union
Carbide in Bhopal, capital city of Madhya Pradesh.
“Many of the town’s 700 000 inhabitants fled to a
hill to escape the gas,” MacKenzie reported, “which
eventually covered an area of 40 square kilometres.”
The final death toll is unclear. In a deposition to India’s
supreme court in 2010, the Indian government quoted
a figure of 5295, with more than 500,000 non-fatal
injuries. Bhopal remains the worst industrial disaster
the world has ever seen.
The culprit was methyl isocyanate gas, an
intermediate in the production of pesticides.
At Bhopal, it was stored as a liquid under pressure in
tanks fitted with pressure valves, spill tanks and air
scrubbers. On the night of 2 December, nearly a tonne
of water being used to clean pipes poured into a tank
holding 40 tonnes of the chemical, resulting in a
runaway reaction.
Evidence emerged within weeks that Union Carbide
had known that safety systems were inadequate at the
plant, incapable of preventing a leak resulting from a
chemical reaction of this magnitude.
The company still maintains that sabotage was the
proximate cause for the leak, however. Although court
cases related to the disaster proliferated in both India
and the US, the only people convicted to date have been
a few Indian managers. “The case,” our correspondent
Fred Pearce wrote in 2013, reflecting on the legal
fallout, “remains a textbook example of the persistent
failure of legal systems to hold multinational
corporations to account for their failures.” Simon Ings