(b) Urban

♤ In urban areas, exposure to indoor air pollution has increased due to a variety of reasons, such as

♤ construction of more tightly sealed buildings,

♤ reduced ventilation,

♤ the use of synthetic materials for building and furnishing and

♤ the use of chemical products, pesticides, and household care products.

♤ Indoor air pollution can begin within the building or drawn in from outdoors.

♤ Other than nitrogen dioxide, carbon monoxide, and lead, there are a number of other pollutants that affect the air quality.