This means that drivers in Delhi in winter could be exposed to levels of the most harmful particulates that are 30 or 40 times the WHO safe limits.
But industry researchers at 3M and DuPont maintain that animals are exposed to levels thousands higher than the general population will ever realistically face.
Of the 300 million exposed to levels of pollution six times over WHO limits, 220 million live in south Asia, where India hosts many of the world's most polluted cities.
An increase in the percentage of urban populations in Europe being exposed to levels of particulate matter from 2010 to 2011 suggested some backsliding, the report said.
China ranked at the bottom on air pollution, with nearly all of its population exposed to levels of PM2.5 pollution deemed unhealthy by the World Health Organisation (WHO).
In the report, the agency did find a few instances in which people might be exposed to levels that pose some health risks: for instance, if a toddler plays in a backyard sprayed recently by a homeowner, or when adults pick fruits in gardens or farms where malathion was recently applied.
But those living outside the evacuation zones have felt left in limbo, exposed to levels of radiation that are several times the normal level, though not high enough to cause observable health risks.
But the debate is not limited to children; the authorities have to weigh the risks of allowing thousands of people, including the elderly, to be exposed to levels that remain far above natural background radiation.
But they raise the prospect that people living near concentrated amounts of cesium are being exposed to levels of radiation above accepted international standards meant to protect people from cancer and other illnesses.
But a study conducted by the Royal Society last year concluded that the majority of soldiers and civilians in the last Gulf war were not exposed to levels of depleted uranium likely to cause what is known as heavy-metal poisoning.
The papers' overall conclusion is that caterpillars are not likely to be exposed to levels of pollen high enough to be harmful, except from one type of the corn that has a particularly high level of the toxin in its pollen.
