A lawn is a deliberately created area of grass, usually kept short by regular mowing and often irrigated, fertilized and treated with chemicals to control weeds and pests.
Lawns are especially common adjacent to and surrounding houses in urban and suburban areas of wealthy countries. They are estimated to cover about 1.9 percent of the contiguous land area in the United States, making them a larger irrigated surface than any single agricultural crop in the country.*
Within cities, lawns can occupy a much larger share of urban land. For example, they account for roughly 30 to 35 percent of the total area of Miami, Florida and even nearly 20 percent for the much larger and denser Los Angeles, California.
Origins
The planting of lawns is rooted in both social history and horticulture. In 16th to 18th century Europe, closely manicured grass surrounding large estates signaled immense wealth because it required valuable land and large amounts of human labor or grazing animals to maintain.
The idea eventually spread to North America, with lawns being established in early American elite gardens and subsequently becoming the standard for suburban neighborhoods. Following the Second World War, the proliferation of mass suburban housing, the development of lawn care products (many adapted from wartime chemical research) and changing cultural expectations turned the green front lawn into a universal symbol of respectability, leisure and middle class success.
Environmental Costs
This cultural norm has substantial environmental, health and other costs. Keeping a lawn uniform and green often requires heavy irrigation, particularly in dry regions, consuming drinking water supplies and stressing rivers and waterbodies during hot months.
Studies indicate that residential lawns often undergo more intensive chemical application per acre, with some estimates suggesting homeowners apply up to ten times more pesticides and herbicides than conventional agricultural land. Because residential chemical use often lacks the rigorous application controls or training required in commercial farming, homeowners can easily over-apply these toxins right where families play.
Fertilizers and pesticides can also move off lawns in runoff and seep into groundwater. Excess nitrogen and phosphorus feed algae growth in waterways, which can reduce oxygen, harm fish and contaminate swimming areas and shellfish beds.
The pesticides can also harm beneficial insects, including pollinators, and may expose people, pets and wildlife to toxic chemicals. Some researchers have linked certain pesticide exposures to neurological effects and other health risks, although the degree of risk depends on the chemical, dose and exposure route.
Harm also results from the production and transport of the fertilizer, water and chemicals. Gasoline powered lawn mowers, trimmers and leaf blowers add further environmental damage through air pollution and greenhouse gas emissions.
Moreover, lawns can also reduce habitat value. A closely cropped, single species grass yard offers little food or shelter for insects, birds and other wildlife.
Health Effects
More than half of the most common lawn chemicals sold at major home improvement stores contain active ingredients identified by independent health researchers as hazardous. For example, widely used herbicides such as 2,4-D and glyphosate (the active ingredient in Roundup) have been heavily scrutinized by researchers, with international health organizations linking them to an increased risk of blood and lymphatic cancers, most notably non-Hodgkin lymphoma.
Many chemical insecticides, such as pyrethroids commonly found in retail garden products, are designed to disrupt the nervous systems of insects. While severe neurodegenerative links are most extensively documented among heavy occupational users like agricultural workers, public health studies suggest that chronic, low-level residential exposure to these chemicals can also contribute to neurological issues, cognitive strain, and potential long-term health risks.
Many lawn chemicals also act as endocrine disruptors. This means they can mimic or block human hormones, potentially leading to reproductive complications, fertility issues, and developmental abnormalities, particularly in children, whose growing hormonal systems are exceptionally sensitive to chemical interference.
Although the full extent of health effects on humans from lawns is not known, it is clear that children are particularly vulnerable. This is because of their greater proximity to the lawns, including commonly sitting directly on the grass, playing barefoot on it and rolling in it. And they frequently put their hands and toys on it, and then put them, or the grass itself, into their mouths. Moreover, highly active children take more breaths per minute than adults and have thinner skin, causing them to absorb toxins at a much higher relative dose while their internal organs are still developing.
Moreover, it is not necessary to physically spend time on grass in order to be exposed. When people or pets walk across a chemically treated yard, residues stick to their shoes, skin and fur, tracking them directly into the home, where they settle into carpets and floor dust. Inside, away from the sunlight and rain that normally break these chemicals down, the toxins can persist for months. Additionally, chemical drifting from a neighbor's chemical spraying can travel dozens of feet (meters) on a breezy day.
Suburban lawns can also pose severe risks to dogs, other pets and some wildlife. Because dogs live close to the ground, sniff intensely and groom themselves by licking their paws, they face a disproportionately high risk of exposure compared to humans.
For example, studies have shown that dogs exposed to lawns treated with 2,4-D have a 70 percent greater risk of developing malignant lymphoma (a form of blood and lymphatic cancer), as well as a significantly increased risk of bladder cancer. Furthermore, backyard ponds or poorly draining lawns can harbor toxic blue-green algae blooms, which can be fatal to dogs even in tiny amounts.
Another disadvantage for households is the fact that maintaining a traditional lawn requires countless hours of labor on a regular basis as well as recurrent monetary expenditures for mowing, watering, edging, weeding, fertilizing and equipment.
Alternatives
There are practical alternatives. Native plant gardens, pollinator-friendly meadows, clover mixes, drought-tolerant ground covers, trees, shrubs and water-permeable paths can replace part or all of a conventional lawn. Once established, many of these options need less mowing, watering and chemical treatment while improving stormwater absorption and supporting biodiversity.
Alternative plantings can also manage rain more effectively. Native plants and deeper-rooted perennials help water soak into the ground rather than run off compacted lawn soil, reducing flooding, erosion and the pollutants carried into streams.
They can also be more resilient. A diverse yard is better able to cope with both dry spells and heavy rain than a uniform, shallow-rooted lawn that depends on regular watering and mowing.
The shift away from the conventional lawn is already visible in public policy. In parts of the western U.S., water utilities and cities offer rebates to property owners who replace lawns with drought-tolerant landscaping, sometimes paying several dollars per square foot (or tens of dollars per square meter).
Change does not require a complete transformation overnight. A household might begin by converting a rarely used strip of grass beside a driveway, replacing part of a backyard with a flower bed or allowing clover and other low-growing plants to remain in the lawn.
Small changes can add up. Leaving grass clippings in place, mowing higher, watering deeply but less often and avoiding routine pesticide use can make an existing lawn less demanding and less polluting.
The goal need not be eliminating every lawn. Where grass is useful for play, gathering or cooling, a smaller, healthier lawn maintained with minimal or no chemicals can coexist with more diverse planting.
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*"Mapping and Modeling the Biogeochemical Cycling of Turf Grasses in the United States," published in Environmental Management (by Cristina Milesi et al., 2005). The researchers utilized high-resolution satellite data, population census records and climate models to estimate that cultivated grass (primarily in residential lawns, parks and golf courses) covers roughly 163,812 square kilometers (over 63,000 square miles). This is roughly the total land area of the U.S. state of Georgia or Wisconsin, and larger than the surface area dedicated to any single irrigated agricultural crop like corn or wheat.