By the authorities
Regular monitoring of the air quality on the American shores of the Gulf of Mexico is being carried out and can be consulted in real time on the site Air Now.
At the same time, the EPA makes air, water, sediment and dispersant monitoring data available to the public.
Movements of the slick are being monitored using satellite imagery as well as aerial reconnaissance flights.
From early May to mid-July 2010, the Canadian National aerial surveillance program carried out 297 hours of flights. An Icelandic team then took the relay.
Slick forecasts are produced twice a day by the National Oceanic and Atmospheric Administration (NOAA).
On 15 May 2010, a monitoring device was installed by the staff of Everglades National Park in order to detect any water contamination.
A team from NOAA "Mussel Watch" program has been sent to the Gulf of Mexico to collect mussel, oyster, water and sediment samples. This national program was initiated in 1986 to continuously monitor contamination of US coastal waters.
By scientific institutes and universities
An ocean mission, originally set up to explore for deep sea corals, has been redirected to collect water and sediment samples from areas near the oil spill source. These samples are expected to provide information for a baseline in order to measure changes if those areas are affected by sinking oil.
Furthermore, BP has committed to financing a 500 million dollar 10 year research programme, in a bid to identify and mitigate the consequences of the spill on the environment.
In August 2010, while American experts agreed on the quantity of oil spilt from the well (4.9 million barrels = 779,000 m³), there appeared to be discrepancies between the National Incident Command (NIC) report and the Georgia Sea Grant Program study on the distribution of the different oil fractions (evaporated, spread, burnt, recovered...) and therefore on the quantities remaining in the Gulf of Mexico.
On 19 August 2010, a team from Woods Hole Oceanographic Institution (WHOI) announced, in a paper published in Science magazine, the detection of a plume of microdroplets of oil. It is reported to be 35 km long by 2 km wide, and 200 m high, and lingering 1,000 m below the surface of the ocean.
In an article published on 6 January 2011 in the magazine Science, scientists at the Universities of Texas, California and New Hampshire showed that all the methane released at sea following the accident had disappeared by September. According to these authors, this disappearance can be explained by blooms of methane-eating bacteria.