The phrase "ash level" is correct and usable in written English.
It can be used in contexts related to measuring the amount of ash, such as in environmental studies, combustion analysis, or cooking.
Example: "The ash level in the soil was significantly higher after the volcanic eruption, affecting local agriculture."
Alternatives: "ash content" or "ash concentration".
The rougher concentrate generated at higher ash level was subsequently processed in different conditions at 35% ash level, and 58% combustibles could be recovered.
Conversely, Chaetomorpha sp. had higher energy and fiber content, but lower ash level (Table 2).
From surface plot (Fig. 10) it is found that no significant clean coal could be obtained at 35% ash level.
(4) In a single stage processing, ash level could be reduced to 37% with a yield of 42%.
Initial stage of processing at a higher ash level generates a reject of high ash with low combustibles.
Cleaning of the rougher concentrate at 34%35%% ash level shows significant improvement in the organic efficiency (88.6%) and useful heat value of clean coal (15690 kJ/kg).
The group's fifth meeting, held this year in Chile two weeks before the Icelandic eruption, invited the aircraft manufacturers to discuss what might constitute safe ash levels.
Airlines and tour operators have expressed scepticism that the ash levels in the atmosphere merited the unprecedented closedown of European airspace.
Sometimes, in an apparent refinement to the analysis, the clean coal yields are normalized for their ash levels before such a comparison is carried out.
The rules, which went into effect at noon Tuesday, require airlines to obtain a certification from their aircraft and engine manufacturers that their planes can safely tolerate the higher ash levels.
In any event, it's clearly important for VA being generated during any particular eruption to be sampled (presumably by drones) and analysed, rather than relying solely on remote measurement of atmospheric ash levels.
