(a) There are approximately 250 million passenger vehicles in the United
States. If each is driven 25,000 km per year, calculate the total mass of CO, NOx and HC emitted in 1970 if all vehicles just meet the government standard at that time. (b) Repeat part (a) for vehicles that just meet the 2001 standard.
(c) Estimate the total reduction in these three pollutants between 1970 and 2001 for vehicles that meet the actual yearly standards compared to the situation where all vehicles remained at the 1970 level.

Question

Quizplus · Accepted Answer

The Answer is

ext { (a) Total km driven per year will be } \left( 250 imes 10 ^ { 6 } ight) imes \left( 25 imes 10 ^ { 3 } \mathrm {~km} ight) = 6.25 imes 10 ^ { 12 } \mathrm {~km} ext {. }

Multiplying the emissions per km for 1970 from the table by the total number of km driven
gives the following:

\begin{array}{lll}\hline ext { pollutant } & ext { emission } \mathrm{g} / \mathrm{km} & ext { total reduction } \mathrm{kg} \\hline \mathrm{CO} & 21.1 & 1.32 imes 10^{11} \\mathrm{NO}_{\mathrm{x}} & 3.1 & 1.94 imes 10^{10} \\mathrm{HC} & 2.5 & 1.56 imes 10^{10} \\hline\end{array}

\begin{array}{l} ext { (b) For } 2001 ext { the emissions are }\\begin{array}{lll}\hline ext { pollutant } & ext { emission } \mathrm{g} / \mathrm{km} & ext { total reduction } \mathrm{kg} \\hline \mathrm{CO} & 2.1 & 1.31 imes 10^{10} \\mathrm{NO}_{\mathrm{x}} & 0.12 & 7.5 imes 10^{8} \\mathrm{HC} & 0.078 & 4.88 imes 10^{8}\end{array}\end{array}

(c) The total emissions are

\begin{array}{lllll}\hline ext { period } & ext { number of years } & \begin{array}{l}\mathrm{CO} \\mathrm{g} / \mathrm{km} imes ext { years }\end{array} & \begin{array}{l}\mathrm{NO} \mathrm{x} \\mathrm{g} / \mathrm{km} imes ext { years }\end{array} & \begin{array}{l}\mathrm{HC} \\mathrm{g} / \mathrm{km} imes ext { years }\end{array} \\hline 1970-1974 & 5 & 21.1 imes 5 & 3.1 imes 5 & 2.5 imes 5 \1975-1979 & 5 & 9.3 imes 5 & 1.9 imes 5 & 0.93 imes 5 \1980 & 1 & 4.3 imes 1 & 1.2 imes 1 & 0.25 imes 1 \1981-1982 & 2 & 2.1 imes 2 & 0.62 imes 2 & 0.25 imes 2 \1983-1993 & 11 & 2.1 imes 11 & 0.62 imes 11 & 0.25 imes 11 \1994-2000 & 7 & 2.1 imes 7 & 0.25 imes 7 & 0.16 imes 7 \2001 & 1 & 2.1 imes 1 & 0.12 imes 1 & 0.078 imes 1 \ ext { totals } & 32 & 200.4 & 36.13 & 21.85 \ ext { 32 y 1970 } & - & 675.2 & 99.2 & 80.0 \ ext { reduction per km } & & 474.8 & 63.07 & 58.15 \& & & & \ ext { total reduction }(\mathrm{kg}) & & 2.97 imes 10^{12} & 3.94 imes 10^{11} & 3.63 imes 10^{11}\end{array}

(A) There Are Approximately 250 Million Passenger Vehicles in the United