You can also use ternary operator for minimizing code.
<tr>
<td ><span class="style2">1</span></td>
<td >PERAK IP-F002</td>
<td style="background-color:<?=($a1==1)?('#00FF00'):('#FF0000');?>"> </td>
<td style="background-color:<?=($a2==1)?('#FF0000'):('#00FF00');?>"> </td>
<td style="background-color:<?=($a3==1)?('#00FF00'):('#FF0000');?>"> </td>
</tr>