Lawn mowers, golf carts and even snow blowers are the latest targets
for the US’s Environmental Protection Agency. After its success in regulating
the big polluters of American air, such as power stations and cars, the
EPA has moved on to smaller fry and last week announced restrictions on
the ‘back-yard polluters’.
According to the EPA, 10 per cent of the ozone and carbon monoxide in
American air can be blamed on ‘non-road emissions’, in other words, petrol-powered
engines other than those in cars and lorries. ‘The small gasoline engines
that Americans use in yard and garden work are a significant source of air
pollution,’ says Carol Browner, head of the EPA.
The agency says the US has 89 million items of lawn and garden equipment.
It calculates that mowing the lawn for one hour produces the same amount
of volatile organic compounds, prime components of smog, as driving a car
30 kilometres. Operating a fork-lift truck for one hour releases as much
nitrogen oxide – another ingredient of smog – as driving 400 kilometres.
The EPA is tackling the problem in two phases. First, manufacturers
of lawn and garden equipment will have to alter the ratio of air and fuel
within new engines, so they burn the petrol more completely and produce
less pollution. A long list of petrol-driven devices comes under the regulation,
including leaf blowers, shredders, fork-lift trucks, portable generators,
air compressors, and pumps and tree stump grinders. All manufacturers must
comply with the regulation by 1996. The EPA believes the changes will increase
the cost of new equipment by less than $5.
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In the second phase that follows, the EPA may impose even more stringent
rules, such as insisting that equipment is fitted with sophisticated antipollution
devices such as catalytic converters.
The agency might also require owners to take their lawn mowers, hedge-trimmers
and other garden equipment for a regular check at government inspection
stations, to make sure they are not producing excess amounts of pollutants.
![Astronomers have long known that understanding how star clusters come to be is key to unlocking other secrets of galactic evolution. Stars form in clusters, created when clouds of gas collapse under gravity. As more and more stars are born in a collapsing cloud, strong stellar winds, harsh ultraviolet radiation and the supernova explosions of massive stars eventually disperse the cloud, and their light can bear down on other star-forming regions in the galaxy. This process is called stellar feedback, and it means that most of the gas in a galaxy never gets used for star formation. Researching how star clusters develop can answer questions about star formation at a galactic scale. Now, the state of the art has been further developed with both Hubble and Webb working together to provide a broad-spectrum view of thousands of young star clusters. An international team of astronomers has pored over images of four nearby galaxies from the FEAST observing programme (#1783), trying to solve this mystery. Their results show that it is the most massive star clusters that clear away their gaseous shroud the fastest, and begin lighting their galaxy the earliest. The team identified nearly 9000 star clusters in the four galaxies in different evolutionary stages: young clusters just starting to emerge from their natal clouds of gas, clusters that had partially dispersed the gas (both from Webb images), and fully unobstructed clusters visible in optical light (found in Hubble images). With Webb???s ability to peer inside the gas clouds, they were able to then estimate the mass and age of each cluster from its light spectrum. This image shows a section of one of the spiral arms of Messier 51 (M51), one of the four galaxies studied in this work, as seen by Webb???s Near-Infrared Camera (NIRCam). The thick clumps of star-forming gas are shown here in red and orange, representing infrared light emitted by ionised gas, dust grains, and complex molecules such as polycyclic aromatic hydrocarbons (PAHs). Within these gas complexes, each tens or hundreds of light years across, Webb reveals the dense, extremely bright clusters of massive stars that have just recently formed. The countless stars strewn across the arm of the galaxy, many of which would be invisible to our eyes behind layers of dust, are also laid bare in infrared light. [Image description: A large, long portion of one of the spiral arms in galaxy M51. Red-orange, clumpy filaments of gas and dust that stretch in a chain from left to right comprise the arm. Shining cyan bubbles light up parts of the gas clouds from within, and gaps expose bright star clusters in these bubbles as glowing white dots. The whole image is dotted with small stars. A faint blue glow around the arm colours the otherwise dark background.]](https://images.newscientist.com/wp-content/uploads/2026/05/13114322/SEI_296271016.jpg)
